Superfund Record of Decision Mound Plant USDOE Area B Operable Unit 1 Miamisburg Oh


                                    EPA/ROD/R05-95/292
                                    1995
EPA Superfund
     Record of Decision:
     MOUND PLANT (USDOE)
     EPA ID: OH6890008984
     OU01
     MIAMISBURG, OH
     06/12/1995

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ENVIRONMENTAL RESTORATION PROGRAM
        OPERABLE UNIT  1
       RECORD OF DECISION
          MOUND PLANT
        MIAMISBURG, OHIO
           June 1995
    U.S. DEPARTMENT OF ENERGY
       OHIO FIELD OFFICE
ENVIRONMENTAL RESTORATION PROGRAM
 EG&G MOUND APPLIED  TECHNOLOGIES
             Final

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CONTENTS

DECLARATION 1

1. SITE NAME AND LOCATION 1

2. STATEMENT OF BASIS AND PURPOSE 1

3. ASSESSMENT OF THE SITE 1

4. DESCRIPTION OF REMEDY 1

5. STATUTORY DETERMINATION 3

6. STATE CONCURRENCE 3

DECISION SUMMARY 6

1. SITE NAME, LOCATION, AND DESCRIPTION 6

2. SITE HISTORY AND ENFORCEMENT ACTIVITIES 8

3. HIGHLIGHTS OF COMMUNITY PARTICIPATION 10

4. SCOPE AND ROLE OF OPERABLE UNIT 11

5. SITE CHARACTERISTICS 12
5.1. History of OU 1 12
5.2. Geologic Setting 15
5.3. Hydrologic Setting 15
5.4. Contaminant Occurrence 17
5.4.1. Soils 17
5.4.2. Groundwater 17

6. SUMMARY OF SITE RISKS 17
6.1. Contaminant Identification 20
6.2. Exposure Assessment 20
6.2.1. Exposure Setting 20
6.2.2. Characterization of Exposure Pathways 22
6.3. Toxicity Assessment 24

6.3.1. Toxicity for Noncarcinogenic Effects 24
6.3.2. Toxicity for Carcinogenic Effects 24
6.4. Risk Characterization 24
6.4.1. Carcinogenic Risk Characterization - Future Resident Farmer Scenario 24
6.4.2. Carcinogenic Risk Characterization - Future Indoor Industrial Park Worker
Scenario 28
6.4.3. Carcinogenic Risk Characterization - Future Outdoor Industrial Park Worker
Scenario 28
6.4.4. Noncarcinogenic Risk Characterization - Future Resident Farmer Scenario .... 29
6.4.5. Noncarcinogenic Risk Characterization - Future Indoor Industrial Park Worker
Scenario 29
6.4.6. Noncarcinogenic Risk Characterization - Future Outdoor Industrial Park Worker
Scenario 30
6.4.7. Risk Characterization 30
6.5. Summary 30

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6.6. Additional Considerations 34
6.6.1. Ecological Risk 34
6.6.2. Immediate Points of Exposure 35
6.7. Risk Assessment for the Selected Industrial Future Use Scenario 35
6.8. Remedial Action Obj ectives 37
6.8.1. Soils 37
6.8.2. Groundwater 37

7. DESCRIPTION OF ALTERNATIVES 37
7.1. Common Elements 39
7.2. Description of the Alternatives 39

8. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 40
8.1. Threshold Criteria 41
8.1.1. Overall Protection 41
8.1.2. Compliance with ARARs 41
8.2. Balancing Criteria 41
8.2.1. Short-Term Effectiveness 44
8.2.2. Long-Term Effectiveness and Permanence 44
8.2.3. Overall Protection of Human Health and the Environment 45
8.2.4. Reduction of Mobility, Toxicity, and Volume Through Treatment 45
8.2.5. Implementability 45

9. SELECTED REMEDY 46

10. STATUTORY DETERMINATIONS 47

11. DOCUMENTATION OF SIGNIFICANT CHANGES 48

RESPONSIVENESS SUMMARY 50

1. OVERVIEW 50

2. BACKGROUND ON COMMUNITY INVOLVEMENT 50

3. SUMMARY OF PUBLIC COMMENTS RECEIVED DURING PUBLIC COMMENT PERIOD AND DOE
RESPONSES 52
3.1. Summary and Response to Local Community Concerns 52
3.2. Comprehensive Response to Specific Legal and Technical Questions 59

4. REMAINING CONCERNS 59
ATTACHMENT A STATE CONCURRENCE LETTER
ATTACHMENT B ARARs TABLES
ATTACHMENT C COMMUNITY RELATIONS ACTIVITIES FOR OU 1, AREA B

FIGURES

1. Topographic features of the Mound Plant area 7
2. Mound Plant OU boundaries 9
3. OU 1 features 13
4. Location of OU 1, showing representative groundwater contours (11/02/93) and plant
production wells 16
5. Conceptual pathway model for OU 1 21

TABLES

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1.     Summary of COPCs 	  18
2.     Toxicity Values - Potential Noncarcinogenic Effects  	  25
3.     Toxicity Values - Potential Carcinogenic Effects  	  26
4.     Slope Factors for Radionuclides of Concern at Mound  Plant 	  27
5.     Carcinogenic Risk Characterization Summary Table  	  31
6.     Noncarcinogenic Risk Characterization Summary Table  	  32
7.     Summary of Risk for OU 1 (Soil and Groundwater) and  Contaminants  with Greatest  Risk
      Contribution 	  36
8.     Preliminary Remediation Goals 	  38
9.     Summary of Remedial Action Alternative Comparison 	  42
10.    Summary of Detailed Cost Analysis 	  43

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                            ACRONYMS
ARAR
BVA
CERCLA
COG
COPC
CTE
D&D
DCA
DCE
DOE
ECAO
FS
ft
HE AST
HI
HQ
IRIS
MCL
MESH
NCP
NPDES
NPL
OAC
OEPA
OU
PCB
PCE
pCi/L
PRG
RAPCA
RfC
RfD
RI
RIR
RME
ROD
SARA
SDWA
TBC
TCA
TCDD
TC E
US EPA
UV
VOC
• g/L
applicable or relevant and appropriate requirements
Buried Valley aquifer
Comprehensive Environmental Response, Compensation, and Liability Act
contaminant of concern
contaminant of potential concern
central tendency exposure
Decontamination and Decommissioning
dichloroethane
dichloroethene
U.S. Department of Energy
Environmental Criteria and Assessment Office (EPA)
feasibility study
feet
Health Effects Assessment Summary Tables
hazard index
hazard quotient
Integrated Risk Information System
maximum contaminant level
Miamisburg Environmental Safety and Health
National Contingency Plan (CERCLA)
National Pollutant Discharge Elimination System
National Priority List (EPA)
Ohio Administrative Code
Ohio Environmental Protection Agency
operable unit
polychlorinated biphenyl
tetrachloroethene
picocuries per liter
preliminary remediation goal
Regional Air Pollution Control Authority
reference concentration
reference dose
remedial investigation
remedial investigation report
reasonable maximum exposure
Record of Decision
Superfund Amendments and Reauthorization Act
Safe Drinking Water Act
to be considered
trichloroethane
tetrachlorodibenzo-p-dioxin
trichloroethene
U.S. Environmental Protection Agency
ultraviolet
volatile organic compound
micrograms per liter

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RECORD OF DECISION
OPERABLE UNIT 1
AREA B, MOUND PLANT, OHIO
June 1995

DECLARATION

1. SITE NAME AND LOCATION

Operable Unit 1, Area B
Mound Plant
Miamisburg, Montgomery County, Ohio

2. STATEMENT OF BASIS AND PURPOSE

This decision document presents the selected remedial action for Operable Unit (OU) 1 at Mound Plant,
Miamisburg, Montgomery County, Ohio, which is one of six distinct areas that comprise one contiguous site as
listed on the National Priorities List (NPL) (Administrative Docket Number VW-90-C-075). This remedial action
was selected in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA), and to the extent
practicable, the National Oil and Hazardous Substances Pollution Contingency Plan. This decision is based on
the administrative record file for this site.

3. ASSESSMENT OF THE SITE

Actual or threatened releases of hazardous substances from this site, if not addressed by implementing
the response action selected in this Record of Decision (ROD), may present an imminent and substantial
endangerment to public health and welfare or the environment.

4. DESCRIPTION OF REMEDY

This OU remedial action is the first of several actions planned as part of the overall remedial action for
the Mound Plant Site. The function of this remedial action is to control groundwater contamination
(primarily dilute volatile organic compounds [VOCs]), to prevent migration of contamination toward the Mound
Plant production wells and to minimize exposure to potential receptors. The pathway of concern consists of
leaching of contaminants from site soils or disposed waste; entrainment in the groundwater flow; and
withdrawal by the Mound Plant production wells or by other, future wells.

This remedial action is not the final remedial action for the Mound Plant Site, but is intended to be a
final remedial action for OU 1. The decisions regarding remedial actions for other portions of the plant
are being addressed in other OUs. These decisions will ultimately be considered in a Site-wide remedial
investigation (RI) and feasibility study (FS), which are in progress. Additional response actions, if
warranted, are yet to be identified or planned. A decision on the final remedial action for the Site will
be made in a subseguent decision-making process.

The selected remedy for OU 1 is collection and treatment of contaminated groundwater and disposal of treated
water. The precise method for treating the contaminated water will be determined during the remedial design
phase of the project. All extracted groundwater will be treated to levels that comply with the reguirements
of the Mound Plant National Pollutants Discharge Elimination System (NPDES) Permit. This remedy was selected
using the remedial evaluation criteria set forth in the National Contingency Plan, 40 CFR Part 300.

The major components of the selected remedy include:

Installing two groundwater extraction wells within OU 1, using standard eguipment and
procedures.

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Treating the extracted groundwater to remove VOCs and other constituents, as reguired, using
cascade aeration, UV oxidation, conventional air stripping, or other suitable treatment units.

Discharging the treated groundwater to the Great Miami River trough the existing plant
NPDES outfall or a new outfall.

Following installation and operation of the groundwater extraction wells, the chemical properties and
hydraulic behavior of the groundwater system will be monitored to verify the adeguacy of the remedy.

5. STATUTORY DETERMINATION

The selected remedy is protective of human health and the environment. It complies with federal and state
reguirements that are legally applicable or relevant and appropriate to the remedial action and is cost
effective. This is a final action ROD.

This remedy uses permanent solutions and alternative treatment technologies to the maximum extent practicable
for this site and satisfies the statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element. While the remedy calls for treatment of
contaminated groundwater, treatment of soil at the site was not found to be practicable. The fact that
the source of contamination is diffuse and no substantive onsite soil hot spots. Exist precludes a remedy
consisting of excavation and treatment of contaminants in soil.

Because this remedy may result in hazardous substances remaining onsite above health-based levels, a review
will be conducted within 5 years after commencement of this remedial action and at 5-year intervals
thereafter to ensure that the remedy continues to adeguately protect human health and the environment.

6. STATE CONCURRENCE

The State of Ohio (Ohio Environmental Protection Agency [OEPA] ) concurs with the selected remedy. The Letter
of Concurrence is attached to this ROD (Attachment A).

JUN 12 1995

Valdas V. Adamkus, Regional Administrator, U.S. Environmental Protection Agency, Region V Date

J. Phil Hamric, Manager, Ohio Field Office, U.S. Department of Energy Date

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RECORD OF DECISION

OPERABLE UNIT 1

AREA B, MOUND PLANT, OHIO

June 1996

DECISION SUMMARY

1. SITE NAME, LOCATION, AND DESCRIPTION

The U.S. Department of Energy (DOE) Mound Plant Site (Figure 1) is located within the southern city limits of
Miamisburg, in Southern Montgomery County, Ohio. The Site is approximately 10 miles south-southwest of
Dayton and 45 miles north of Cincinnati. Miamisburg is predominantly a residential community with some
supportive commercial facilities and limited industrial development. Much of the residential, commercial, and
industrial development within a 5-mile radius of the Site is concentrated on the Great Miami River
floodplain. The adjacent upland areas are used primarily for residences and agriculture or are unused open
spaces.

Mound Golf Course and Miamisburg Mound State Memorial Park, both directly east of the facility across Mound
Road, are heavily used during favorable weather. The park is the site of a 68-ft-high ancient Indian mound,
located 380 ft east of the Mound Plant boundary. Other recreational areas within 1 mile of the facility
include the Miamisburg municipal park and swimming pool (located immediately west of Mound Plant), Harmon
Athletic Field, and Library Park. These areas are used extensively during the summer.

There are no large lakes within a 5-mile radius of the Site. Some vestiges of the old Miami-Erie Canal lie
between the Conrail Railroad and the Dayton-Cincinnati Pike west of the site. This remnant of the old
Miami-Erie Canal is designated as OU 4. The major water body in the vicinity of the Mound Plant is the Great
Miami River. It is approximately 150 to 200 ft wide in this area.

Agricultural land within a 5-mile radial area around the Site is primarily used for corn and soybean
production and for livestock grazing.

According to 1990 census figures, the population of Miamisburg is 17,834, Dayton is 182,044, and Montgomery
County is 573,809.

The only historic landmark in the vicinity of Mound Plant is the Miamisburg Mound, an ancient Indian mound
located 280 ft east-southeast of Mound Plant in Miamisburg Mound State Memorial park. The mound - a
symmetrical, conical earthwork 68 ft high and 800 ft in perimeter - is one of the largest of its type. It is
believed to be the sepulcher of a chief of the Adena culture of Mound Builders who inhabited the Ohio region
as early as 800 B.C.

OU 1 also includes the three plant production wells located along the southern plant boundary. An extended
discussion of OU 1 history, including waste disposal and construction activities, is provided in the RI
report (RIR).

The former waste disposal sites within OU 1 (the historic landfill and associated features) are concentrated
within, beneath, and immediately adjacent to the current site sanitary landfill. These waste disposal sites
are the result of a long history of dumping, burning, moving, reworking, burying, and partially removing
wastes and placing them into the engineered structure (the Site sanitary landfill). Currently, the area
bounded by the overflow pond to the north, the paved roads to the west and south, and the bunker area to the
east can be considered a single entity. It is internally heterogeneous; not all portions are contaminated.
However, subdividing the area does not increase understanding of the transport phenomena that are occurring,

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nor does it facilitate developing remedial alternatives.

2. SITE HISTORY AND ENFORCEMENT ACTIVITIES

Mound Plant was established at its present location in 1948. Currently, the facility is operated by EG&G
Mound Applied Technologies for DOE as an integrated research, development, and production facility that
supports the DOE weapons and energy programs. To reconfigure and consolidate the nuclear complex, DOE has
decided to phase out the future defense mission. As a result, the Mound Site has been designated an
environmental management site and the plant is in the process of being converted into a commercial and
industrial site.

OU 1, also identified as Area B, occupies approximately 4 acres in the southwestern portion of the Mound
Plant (Figure 2). OU 1 includes a historic landfill site that was used by the Mound Plant from 1948 to 1974.
Plant waste materials that were disposed of in OU 1 included general trash and liguid waste. Much of this
waste was later relocated and encapsuled in a site sanitary landfill constructed in 1977. An overflow pond
was constructed at the same time, partially covering the historic landfill site. After 1974, waste was no
longer disposed of in OU 1. There are known releases of volatile VOCs from OU 1 into the adjacent Buried
Valley aguifer (EVA). In addition, tritium was detected in water samples taken from wells in OU 1, although
the concentration was below the drinking water
maximum contaminant level.

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Because of the magnitude and complexity of the Mound Plant RI/FS, the Site has been divided into OUs
as a means of managing the investigation. OUs 1, 2, 4, 6, 6, and 9 generally divide the Mound Plant Site
into the geographic areas shown on Figure 2. These OUs and current objectives are as follows:

Area B, OU 1, is the subject of this ROD. It occupies approximately 4 acres in the
southwestern portion of the Mound Plant. OU 1 includes a historic landfill site that was
used by the Mound Plant from 1948 to 1974. Plant waste materials that were disposed
of in OU 1 included general trash and liquid waste. Much of this waste was later relocated
and encapsuled in a site sanitary landfill constructed in 1977. An overflow pond was
constructed at the same time, partially covering the historic landfill site. After 1974, waste
was no longer disposed of in OU 1. There are known releases ot VOCs from OU 1 into the
adjacent BVA. In addition, tritium has been detected in water samples taken from wells
in OU 1, although the concentration was below the drinking water maximum contaminant level.

Main Hill, OU 2, includes potential release sites on the Mound Plant Main Hill, including
some peripheral groundwater seeps. The scope of investigation includes characterization
of the indurated bedrock and unconsolidated overburden on the Main Hill, associated soils,
and groundwater.

Miami-Erie Canal, OU 4, addresses an abandoned segment of the Miami-Erie Canal west
of Mound Plant that contains plutonium-contaminated sediment; (from a 1969 waste-line
break) and tritium-contaminated soils. It is 1 mile long, and is considered to be one
potential release site.

South Property, OU 5, includes soils with known or suspected radioactive contamination,
as well as the geographical area of the SM/PP Hill, the Plant Valley, and the New Property.
The sites within OU 5 are not currently scheduled for decontamination and
decommissioning (D&D) under the D&D Program at Mound Plant. It is anticipated that, as
sites obtain funding under the D&D Program, they may be moved from OU 5 to OU 6,
described below. As with the Main Hill, investigations of the potential source terms on the
SM/PP Hill may require characterization of the bedrock and unconsolidated overburden.

D&D Program Sites, OU 6, includes potential release sites with radioactively contaminated
soils that are undergoing cleanup or are scheduled for cleanup in the near future. Because
it is already known that the contaminated soil will be cleaned up, and because the D&D
Program is an ongoing activity (under the Atomic Energy Act) that reduces potential
impacts to human health and the environment, the scope of the RI/FS for these sites is
verification of cleanup after the soil is removed. The cleanup levels are to be determined
through the CERCLA risk assessment process.

Site-wide RI/FS, OU 9, includes off-plant migration of contaminants in groundwater, soils,
surface water and sediments, air, and flora and fauna. In addition, the Site-wide RI/FS will
ensure that a comprehensive investigation is performed by compiling all data from
individual OU investigations into a comprehensive report. Data reports from specific
site-wide investigations conducted under this work plan will be initially reported in interim
reports or technical memoranda to ensure that the off-plant and regional data are available
early.

OU 1 encompasses an historical waste disposal area (landfill) from which there have been known releases of
VOCs to the BVA, a sole-source aquifer. The cleanup remedy for OU 1 is selected from the alternatives
discussed in the FS, which is available to the public for review. The contaminated groundwater in OU 1 is a
principal threat at this site because of the possible offsite migration of the VOC-contaminated plume and the
potential for direct ingestion of contaminants through drinking water wells. The soil contaminants in OU 1
are restricted to the area of past disposal activity with no discernible source detected.

5. SITE CHARACTERISTICS
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5.1. History of OU 1

Cut-and-fill activities and refuse and waste disposal have occurred within OU 1 from 1948 to 1974. However,
no written manifests of the waste types and quantities exist, and uniform disposal practices were not
followed.

Before 1947, OU 1 was a residential area with two or three small houses and storage buildings. During plant
construction, the area was exploited for its gravel deposits. Removal of gravel was routine until 1977. The
gravel pit, as well as the waste disposal features discussed below, are shown in Figure 3.

The old gravel excavation and the disturbed area just north of the excavation were used for landfill,
including open burning of trash and garbage from plant operations. A burn cage, consisting of a wire mesh
structure that caught ashes from burning wood, paper, and other materials, was used. Solid waste, mostly
paper, office, end kitchen garbage, was placed in the burn cage and ignited to reduce its volume.

In 1954, the first burial in OU 1 occurred along the southern boundary of the old gravel guarry, just north
of and parallel to the east-west road that climbs the SM/PP Hill. A backhoe was used to excavate an
irregularly shaped trench to the maximum depth possible. Residual steel and metal debris (such as rebar and
pipe), the result of a fire that consumed the Dayton Unit salvage materials on another part of the plant (now
Area 13), were progressively buried in the trench. The debris and backfill were regraded to just below the
road level.

During 1955 and possibly 1956, empty drums that had contained thorium were buried in the southwest corner of
OU 1. A shallow excavation was made, and about 2,500 55-gallon drums were crushed and then covered with a
thin layer (about 1 to 2 ft) of soil cover. The buried drums and backfill were regraded to just below the
level of the road.

In 1959, the state of Ohio banned open burning, and Mound Plant prohibited open burning of solid and liguid
waste in OU 1. Hazardous liguid waste was collected and disposed of offsite. Solid waste was placed in
east-west-trending trenches cut by a bulldozer.

In 1977 and 1978, the overflow pond and site sanitary landfill were constructed on the site of OU 1. The
overflow pond was built to complement the low-flow retention basins, which were constructed in 1976 on the
lower reach of the plant drainage ditch. Much of the solid waste in the historic landfill was excavated and
moved to the site sanitary landfill. Generally, debris from the Dayton Unit fire in the first trench and
empty, crushed drums that had contained thorium in the second trench were not excavated and remained under
the landfill. The volume excavated was limited by the volume required for the pond construction.

The pond was built with a natural clay-bearing compacted glacial till liner and earthen dikes. It has a
5,000,000-gallon capacity. Effluent in the overflow pond is discharged through a standpipe in the northwest
corner of the pond to the stilling basin below the low-flow retention basins. It then goes to the Miami-Erie
Canal and to the Great Miami River through NPDES Outfall 002 at a rate of approximately 660,000 gallons per
day.

The site sanitary landfill was constructed with a 4- to 5-ft-thick clay liner consisting of onsite materials
and a cap of 3 ft of clay with 2 to 5 ft of low-permeability topsoil. The clay liner was compacted to ensure
a proper seal and integrity over time. A leachate collection system was constructed using collection drains
at the top of the lower clay liner of the landfill. The drains located in the landfill allow any landfill
liquids to move into the adjacent overflow pond. Five french drains were installed 2 to 25 ft below the
landfill liner, partially in a fine gravel/sand layer and partially in a silty clay layer. These french
drains drain moisture from under the site sanitary landfill to ensure soil slope stability.

A thin (< 2-ft-thick) layer of burned trash on the west side was excavated directly beneath the landfill
site. Approximately 100,000 cubic yards of trash was moved from the overflow pond site to the landfill.
According to personal accounts, some of the trash was saturated during excavation and the liquid flowed from
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the drain pipe into the pond for 6 months afterward. No known samples of this leachate were collected. No
known drainage has occurred since the initial 6-month period. The height of the landfill was surveyed and
checked for settling a year or two after construction. Although no known written report exists, a verbal
report suggests little or no settling occurred.

Currently (1995), OU 1 remains much as it did in 1978 after the overflow pond and site sanitary landfill
were constructed. The road along the north and west boundary has been paved and, in the 1980s, a bridge was
built over the overflow channel from the plant drainage ditch to the overflow pond.

Numerous monitoring wells have been installed around OU 1 as par of area environmental investigations.

5.2. Geologic Setting

OU 1 is partially located on a buried bedrock shelf that drops off to the west, north, and south. The
surface of the bedrock is a preglacial erosional surface that is weathered, but grades rapidly into competent
material. The bedrock section subjacent to OU 1 is dominated shale with a significant limestone-bearing
portion truncated by erosion immediately beneath the site sanitary landfill. The next
nearest (vertically) significant limestone portion is approximately 30 ft lower in the section and does
not intersect the bedrock interface until some distance to the west of OU 1, at or beyond the plant boundary.
The opportunity for contaminant transport from OU 1 through limestone layers does not exist.

The bedrock is overlain by glacial outwash materials, glacial till, and artificial ill. The outwash
materials that contain the BVA thin eastward against the Buried Valley margin, which is beneath the western
edge of OU 1 adjacent to the waste disposal areas (site sanitary and historic landfills). Only the western
portion of the site sanitary landfill overlies the BVA. The eastern portion overlies the bedrock shelf. To
the north, these outwash materials extend up the Plant Valley. The portion of the BVA immediately adjacent
to OU 1 (to the west) varies from 0 to 40 ft thick an is relatively free of fine-
grained till layers within the outwash. Typical transmissivities are high (between 30,000 and 50,000
ft2/day).

5.3. Hydrologic Setting

Groundwater occurs primarily in the outwash sediments of the BVA or in its extension up the Plant Valley.
Within the valley, gradients are steep and are governed by topography and the thickness of the unconsolidated
zone; flow is west-southwest along the valley axis. In he main part of the BVA, to the west of OU 1,
gradients are nearly flat; flow is generally south, governed by the interrelationships among recharge, river
stage, and the pumping of the Mound Plant production wells. In the immediate vicinity of OU 1, flow is
governed by the plant production wells and is southward toward the pumping well, Well 0076 (Figure 4). Well
0076 is the primary plant production well.

The waste materials and contaminated soils within OU 1 are partially isolated from the hydrologic
environment. Much of the surface is engineered to provide rapid runoff. The materials immediately below the
waste disposal area are dominantly fine-grained, which may inhibit the downward movement of water and
contaminants. The water table is at or below the bedrock interface in this area, so the unconsolidated
materials are also in the vadose zone. However, during periods of high seasonal groundwater, some waste
materials or contaminated soil are exposed to circulating waters.

5.4. Contaminant Occurrence

Contaminated media at OU 1 include both soils and waste materials within the site and the groundwater system
beneath and adjacent to the site. Chemicals of potential concern (COPC) from the Baseline Risk Assessment
are identified in Table 1.

5.4.1. Soils
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The only discernible pattern for all the compounds detected during the surface and subsurface soil sampling
appears directly related to activities in and around the site sanitary landfill. A single major
source of the contaminants has not been detected and is not believed to exit. Rather, it is believed that a
random pattern of dispersed contamination is the source of the compounds. While not exceeding established
regulation limits, tetrachloromethane is present at risk-based levels of concern (see section 6.3)

5.4.2. Groundwater

The recent groundwater sampling data (June 1992 through March 1993) identified five VOCs at levels above
proposed or established regulatory limits (40 CFR 141 ) in the groundwater beneath OU 1. These VOCs are
vinyl chloride (chloroethene), trichloromethane (chloroform), 1,2-cis-dichloroethene (DCE), TCE, and
tetrachloroethene (PCE) . Only one VOC, 1,1,1-trichloroethane (TCA) , shows concentrations offsite; the
pattern of occurrence suggests a source outside OU 1. The general area impacted by VOCs is indicated in
Figure 4. Two metals (chromium and nickel) were detected above primary drinking water standards from
December 1991 to March 1993. No consistent trend exists for concentrations of metals in the area.

6. SUMMARY OF SITE RISKS

Based on analytical data collected during the RI, a Baseline Risk Assessment was performed using site-
related contaminants. The Baseline Risk Assessment assumes no corrective action will take place and that no
site use restrictions or institutional controls, such as fencing, groundwater use restrictions, or
construction restrictions, will be imposed. The risk assessment determines actual or potential carcinogenic
risks and/or toxic effects that the contaminants at the site pose under current and future
land use assumptions. Therefore, the assessment serves as a baseline case that can be used to compare the
relative effectiveness of alternative remedial strategies in reducing public health risks. This Baseline Risk
Assessment focuses on exposure of hypothetical future workers or residents to soil and groundwater
contamination.

The Baseline Risk Assessment estimates risk associated with potential pathways identified by the conceptual
site model presented in Figure 5. It also identifies pathways that exceed acceptable risk,
so that the remediation process is focused on pathways that present a threat to human health and the
environment.
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Table 1. Summary of COPCs

Groundwater

The organic COPCs for groundwater are:

- 1,1,1 -TCA 20/»g/L
- 1,2-cis-DCE 640 (J)
- bis-(2-ethylhexyl)phthalate 0.23 (J)
chlordane (alpha) 0.061
- diethyl phthalate 10 (J)
pyrene 10 (J)
- PCE 290 (J)
tetrachloromethane 5 .1
- TCE 160
trichloromethane 130(J)
trichlorofluoromethane 12
vinyl chloride 17

The radioactive COPCs (that exceeded background levels) are:

- actinium-227 2.27 pCi/L
- plutonium-238 0.057
- plutonium-239/240 0.263
- strontium-90 0.766
- tritium 13,500
- uranium-235 and -236 0.188
- uranium 238 1.46

The following radionuclides were retained as groundwater COPCs because they are daughter products of the
radionuclides that were found to exceed background levels:

- radium-226 2.61 pCi/L
- thorium-228 0.97 (J)
- thorium-230 3.86
- thorium-232 0.588 (J)
- uranium-234 0.782

Soil

The organic COPCs for soils are:

- 1,2,3,4,6,7,8-HpCDF 214 pg/g
- 1,2,3,4,6,7,8-HpCDD 259
- 1,2,3,4,7,8,9-HpCDF 41.4
- 1,2,3,4,7,8-HxCDD 8.5
- 1,2,3,4,7,8-HxCDF 209
- 1,2,3,5,7,8-HxCDF 63.2
- 1,2,3,6,7,8-HxCDD 28.3
- 1,2,3,7,8,9-HxCDD 39.7
- 1,2,3,7,8-PeCDF 43.2
- 2,3,4,6,7,8-HxCDF 64.1
- 2,3,4,7,8-PeCDF 150
- 2,3,7,8-TCDD 22.5

- 2,3,7,8-TCDF 132
-------
Table 1. (page 2 of 2)
Soil (Continued)
OCDD
OCDF
1,2-DCE
4-methyphenol
aroclor-1248
benzo(a)anthracene
benzo pyrene
benzo(k)fluoranthene
benzo(k)fluoranthene
benzoic acid
bis(2-ethylhexyl)phthalate
vinyl chloride
chrysene
dichloromethane
fluoranthene
indeno(1,2,3-cd)pyrene
phenol
pyrene
PCE
toluene
TCE
2110
163
6,700/«g/kg
290
220,000
3,400
2,500
4,000
4,000
1,700
5,600
190
2,600
81
8,300
1,200
120 (J)
7,200 (J)
24,000
7,100
970 (J)
inorganic COPCs consist of:

fluoride
nitrate
silver
12.6 mg/kg
16.87
6.3
The radioactive COPCs (that exceeded background levels) are:

- plutonium-238 17.8 pCi/g
- plutonium-239/240 1.2
- strontium-90 5.78
tritium 40.3
The following radionuclides were retained as soil COPCs because they are daughter products
of the radionuclides that were found to exceed background levels:
- thorium-228
- thorium-232
- uranium-235/236

COPC - contaminants of potential concern
DCE - dichloroethene
(J) - estimated guantity
mg/kg - milligram per kilogram
• g/kg - microgram per kilogram
PCE - tetrachloroethene
1.3 pCi/G
1.04
6.091 (J)

pCi/g - picocuries per gram
pCi/L - picocuries per liter
pg/g - picogram per gram
TCA - trichloroethane
TCE - trichloroethene
- contaminant contributing significant risk
-------
6.1. Contaminant Identification

The levels of contamination found in the different media at the Site are reported in the RIR. Identification
of contaminants of potential concern (COPCs) is presented in Section 5 of the RIR. The
COPCs were listed in Table 1. As discussed in section 6.4 below, the list of COPCs was reduced to only those
contaminants that contribute significantly to the risk. These are highlighted in Table 1.

6.2. Exposure Assessment

The objective of the exposure assessment is to estimate the type and magnitude of exposures to COPCs that are
present at or migrating from Area B. The exposure pathway is the mechanism by which an individual or
population is exposed to chemicals at or originating from a site. Each exposure pathway reguires a source or
release from a source, an exposure point, and an exposure route.

6.2.1. Exposure Setting

The exposure setting, which includes Area B climate, vegetation, groundwater hydrology, and other
characteristics, is described in detail in the RIR. The nearest populations are less than 750 ft west of
OU 1, within the city of Miamisburg. The 1990 census gives the population of Miamisburg as 17,834, Dayton as
182,044, and Montgomery County as 573,809. Miamisburg is predominately a residential community, with some
supportive commercial facilities and limited industrial and agricultural development.

Most of the residential, commercial, and industrial development within a 5-mile radius of the site is
concentrated on the Great Miami River floodplain. The adjacent upland areas are used primarily for
residences and agriculture or are unused open spaces. Agricultural land within a 5-mile radius of the
site is primarily used for corn and soybean production and livestock grazing.

The major water body in the vicinity of OU 1 is the Great Miami River. It is approximately 150 to 200
ft wide in this area. The river is used for pleasure boating and sport fishing, primarily during the
summer. Swimming is not permitted in the river.

6.2.2. Characterization of Exposure Pathways

OU 1 is located within a government-owned and restricted facility. Unrestricted access and development of
the site is possible only if DOE releases the property. No one presently lives on or otherwise uses the
property; current workers do not work on a continual basis within Area B.

Three OU 1 production wells supply or have supplied water to the Mound Plant. One well, production well
0071, is no longer in use because volatile organic contaminants were detected at concentrations exceeding
USEPA maximum contaminant levels (MCLs) and Ohio drinking water standards. The other two wells, production
wells 0076 and 0271, are still in use and have organic concentrations below EPA MCLs and Ohio drinking water
standards. Since Mound Plant is taking water from OU 1 that meets acceptable drinking water standards, a
current worker scenario was not considered for the Baseline Risk Assessment.

The Baseline Risk Assessment involves 1) the determination of contaminant concentrations at exposure points
for a future resident farmer scenario and future indoor and outdoor industrial park worker scenarios, and 2)
the estimation of contaminant intake through potential exposure pathways.

Two types of exposures were evaluated for the future farmer resident scenario. These exposure types are
denoted as the reasonable maximum exposure (RME) and the central tendency exposure (CTE). The RME is defined
as a "reasonable worst case" that is conservatively high, yet still has a reasonable likelihood of occurring.
Key features of an RME are that one would expect at least 90 percent of actual exposures to be lower and that
it could occur. The CTE, on the other hand, is an "average case." Fifty percent of actual exposures are
expected to be lower or higher than the CTE. High exposures will typically fall between the CTE and the RME.
-------
The exposure scenario for the future farmer resident includes all potential pathways identified in the site
conceptual model that could lead to quantifiable exposure. The farmer is assumed to be exposed through the
following routes:

Ingestion of groundwater.

Incidental ingestion of and dermal contact with surface water while swimming.

Dermal contact and inhalation of VOCs while showering with groundwater.

Inhalation of resuspended dust while plowing/cultivating crops and garden produce and
under usual dust resuspension conditions.

Incidental ingestion of soil.

External exposure to radiation emitted from radionuclides in soil.

Dermal contact with chemicals in soil.

Ingestion of homegrown produce grown in contaminated soil.

Ingestion of livestock that have ingested contaminated soil and contaminated plants.

It is assumed that the future onsite industrial park worker will work within the Area B location for 25
years (RME). For the CTE, it is assumed that the worker will be employed on the site for 9 years (assumed
egual to residential). As with the future farmer resident, the source of water for the industrial park comes
from contaminated onsite wells that workers use for showering at the end of the workday.

In the future indoor industrial worker scenario, it is assumed that the worker performs job duties within
a structure or building for 8 hours a day, 250 days a year. The indoor worker is assumed to be exposed
through the following routes:

Ingestion of groundwater.

Inhalation of indoor vapors.

Inhalation of indoor particulates.

Inhalation of VOCs while showering with groundwater.

Dermal contact with contaminants while showering with groundwater.

For the future outdoor industrial worker scenario, the following exposure routes were evaluated:

Ingestion of groundwater.

Inhalation of outdoor particulates and vapors.

Ingestion of soil.

Dermal contact with chemicals in soil.

Inhalation of VOCs while showering with groundwater.

Dermal contact with chemicals while showering with groundwater.

6.3. Toxicity Assessment
-------
The purposes of the toxicity assessment are to weigh available evidence regarding the potential for
particular contaminants to cause adverse effects in exposed individuals and to provide an estimate of the
relationship between the extent of exposure to a contaminant and the increased likelihood and/or severity of
adverse effects. This includes the preparation of fate and toxicity profiles for each of the chemicals and
identification of human health criteria. The sources of toxicity data include the Integrated Risk
Information System (IRIS), the Health Effects Assessment Summary Tables (HEAST), the USEPA Environmental
Criteria and Assessment Office (ECAO), and USEPA Region III.

6.3.1. Toxicity for Noncarcinogenic Effects

The USEPA Office of Research and Development has calculated acceptable intake values, denoted as reference
doses (RfDs) or reference concentrations (RfCs), for long-term (chronic) exposure to noncarcinogens. The
most recent oral RfDs and inhalation RfCs of the COCs and the associated sources are summarized in Table 2.

6.3.2. Toxicity for Carcinogenic Effects

For chemical carcinogens, the EPA Office of Research and Development has calculated estimates of the
carcinogenic potential. These estimates, or slope factors, correlate intake of a carcinogen with an
increased risk of cancer. The most recent oral and inhalation slope factors from IRIS, HEAST, USEPA, and
ECAO, along with evidence and slope factor sources for COCs, are summarized in Table 3.

The USEPA currently classifies all radionuclides as Group A, known human carcinogens. The ingestion,
inhalation, and ground exposure slope factors for the various radionuclides of concern at Mound Plant are
summarized in Table 4.

6.4. Risk Characterization

In this section, toxicity and exposure assessment are summarized and integrated into guantitative expressions
of risk. Both noncarcinogenic and carcinogenic effects are evaluated.

6.4.1. Carcinogenic Risk Characterization - Future Resident Farmer Scenario

For potential carcinogenic risks, the probability that an individual will develop cancer over a lifetime
of exposure is estimated from daily intakes and dose response information (carcinogen potency factors).
Carcinogenic risk depends on three factors: the dose, the carcinogenic potency of the chemical or
radionuclide, and the exposure duration. To calculate carcinogenic risk, the products of the individual
chemical exposures and carcinogenic slope factors were summed to provide the estimated risk to the future
resident.
-------
Table 2. Toxicity Values - Potential Noncarcinogenic Effects
Chemical
Organic Chemicals

1,2-cis-Dichloroethene
1,2-Dichloroethane
2,3,7,8-TCDD (Dioxins)
Archior-1248 (PCB)
Benzo(a)pyrene
Chlordane (alpha) ....
Tetrachloroethene (PCE)
Tetrachloromethane
Trichloroethene ....
Trichlormethane ....
Vinyl chloride
Chronic Inhalation Rf
(mg/m3)
l.OE-02
RfC Source
ECAO
2.0E-03
ECAO
Chronic Ingestion RfD
(mg/kg/day)
l.OE-02
6.0E-05
l.OE-02
7.0E-04
6.0E-03
l.OE-02
RfD Source
HE AST
IRIS
IRIS
IRIS
ECAO
IRIS
ECAO - USEPA Environmental Criteria and Assessment Office
IRIS - Integrated Risk Information System
HEAST - Health Effects Assessment Summary Tables
mg/kg/day - milligrams per kilogram per day
mg/m3 - milligrams per cubic meter
RfC - reference concentration
RfD - reference dose
-------
Table 3. Toxicity Values - Potential Carcinogenic Effects
Chemical

Organic Chemicals

1,2-cis-Dichloroethene
1,2,Dichloroethene
2,3,7,8-TCDD (Dioxins)
Aroclor-1248 (PCB)
Benzo(a)pyrene
Chlordane (alpha)
Tetrachloroethene (PCE)
Tetrachloromethane
Trichloroethene
Trichloromethane
Vinyl chloride
USEPA Weight of
Evidence
D
B2
B2
B2
B2
B2
NA
B2
NA
B2
A
Inhalation Slope Factor
2.6E-05
3.3E-11
1.7E-03
3.7E-04
5.8E-07
1.5E-05
1.7E-06
2.3E-05
8.4E-05
Inhalation Slope
Factor Source
IRIS
HE AST

HE AST
IRIS
ECAO
IRIS
ECAO
IRIS
HE AST
Ingestion Slope Factor
(1/mg/kg/day)
9.1E-02
1.5E +05
7.7E +00
7.3E +00
1.3E +00
5.2E-02
1.3E-01
1.1E-02
6.1E-03
1.9E +00
Ingestion Slope
Factor Source
IRIS
HE AST
IRIS
IRIS
IRIS
ECAO
IRIS
ECAO
IRIS
HE AST
aKey:

A = Known human carcinogen
Bl = Probable human carcinogen, limited human data
B2 = Probable human carcinogen, inadeguate or no human data
C = Possible human carcinogen
D = Not classifiable as human carcinogen
E = Evidence that not carcinogenic in humans

ECAO - USEPA Environmental Criteria and Assessment Office
HEAST - Health Effects Assessment Summary Tables
IRIS - Integrated Risk Information System
pg/m3 - micrograms per cubic meter
mg/kg/day - milligrams per kilogram per day
NA - Weight of evidence information not available
USEPA - U.S. Environmental Protection Agency
-------
Table 4. Slope Factors for Radionuclides of Concern at Mound Plant
Radionuclides
Actinium-227 +
Plutonium-238
Plutonium-239
Plutonium-240
Radium-226 + D
Strontium-90 +
Tritium
Ingestion
(Risk/pCi)

3.5E-10
2.2E-10
2.3E-10
2.3E-10
1.2E-10
3.6E-11
5.4E-14
Inhalation (Risk/pCi)
Ground Surface
(Risk/year per pCi/g)
.8E-08
.9E-08
.8E-08
.8E-08
.OE-09
6.2E-11
7.8E-14
aAll radionuclides have an A (known human carcinogen) weight of evidence classification.

D - daughter
pCi - picocuries
pCi/g - picocuries per gram
2
5E-07
8E-11
1.7E-11
2.7E-11
6.0E-06
O.OE + 00
O.OE + 00
-------
Future resident farmer RME carcinogenic risks to the child and adult from all chemicals, radionuclides,
and pathways are 2 excess cancers per 10,000 persons exposed and 5 excess cancers per 10,000 persons exposed,
respectively. The overall CTE carcinogenic risks to the child and adult are 4 excess cancers per 100,000
persons exposed and 1 excess cancer per 10,000 persons exposed, respectively.

For the future resident farmer scenario, the ingestion and inhalation pathways contribute more than 80
percent of the carcinogenic risk. The remainder of the carcinogenic risk is attributable to dermal contact.
The overall carcinogenic risk due to external radiation exposure is less than 1x10-7.

The overall carcinogenic risks posed by groundwater are 6x10-4 and 1x10-4 for the RME and CTE, respectively.
The overall risks (RME and CTE) Posed by soil COPCs are more than one order of magnitude less than those for
groundwater.

6.4.2. Carcinogenic Risk Characterization - Future indoor Industrial Park Worker Scenario

For the future onsite indoor worker, the overall RME and CTE risks were found to be 2x10-4 and 5x10-5,
respectively (does not include daughter product radionuclides). PCE had the highest RME risk of 8x10-5.
Groundwater COPCs contribute virtually all of the carcinogenic risk (greater than 99 percent). The soil RME
and CTE risk levels are less than the lowerbound value of the USEPA target risk range.

6.4.3. Carcinooenic Risk Characterization - Future Outdoor Industrial Park Worker Scenario

For the future onsite outdoor worker, the overall RME and CTE risks were found to be 1x10-4 and 2x10-5,
respectively (does not include daughter product radionuclides). The ingestion and dermal contact pathways
contribute approximately 83 percent of the carcinogenic risk. PCE had the highest RME risk of 7x10-5.
Groundwater COPCs contribute the majority (approximately 95 percent) of the overall RME and CTE carcinogenic
risks.

6.4.4. Noncarcinogenic Risk Characterization - Future Resident Farmer Scenario

Noncarcinogenic risk was evaluated by calculating the hazard guotient (HQ), which is the ratio of the
estimated daily exposure of each contaminant, to the applicable chronic RfC or RfD for that contaminant. The
HQs were then summed to derive a hazard index (HI) for each exposure route and for all exposures combined.
All RME and CTE noncarcinogenic HQs and His from all pathways are presented in the RIR.

An HI of greater than 1.0 at any time during an individual's lifetime indicates that there may be a
potential for noncarcinogenic effects. The overall RME His for the child and adult in the future farmer
scenario are 21 and 18, respectively. For the future farmer CTE, the overall His are 12 for the child
and 11 for the adult.

For the future farmer scenario, the inhalation pathway contributes to approximately 80 percent of the
overall noncarcinogenic risk. Tetrachloromethane, TCE, and PCE were the only COPCs with overall RME His
exceeding unity. These COPCs contributed to approximately 90 percent of the overall noncarcinogenic risk.
Tetrachloromethane had the highest overall RME a d CTE HI of 31 and 20,
respectively.

Groundwater COPCs contribute virtually all of the noncarcinogenic risk (greater than 99 percent). The
soil RME and CTE His are two orders of magnitude less than unity.

6.4.5. Noncarcinogenic Risk Characterization - Future Indoor Industrial Par Worker Scenario

For the future indoor industrial park worker scenario, the overall RME and CTE His were 17 and 11,
respectively. The inhalation pathway contributes approximately 96 percent of the overall noncarcinogenic
risk. Tetrachloromethane had the highest RME and CTE His of approximately 15 and 10, respectively.

Tetrachloromethane was the only COPC with RME and CTE His that exceeded unity. The overall RME and CTE His,
with the exception of tetrachloromethane, were found to be below unity. The groundwater COPC His contributed
-------
almost 100 percent of the noncarcinogenic risk. The soil COPC His were approximately 10 orders of magnitude
less than unity.

6.4.6. Noncarcinogenic Risk Characterization - Future Outdoor industrial Park Worker Scenario

For the future outdoor industrial park worker scenario, the overall RME and CTE His were 15 and 9,
respectively. The inhalation pathway contributes approximately 95 percent of the overall noncarcinogenic
risk. Tetrachloromethane had the highest RME and CTE His of approximately 14 and 9, respectively.

Tetrachloromethane was the only COPC with RME and CTE His that exceeded unity. The overall RME and CTE His,
with the exception of tetrachloromethane, were found to be below unity.

The groundwater COPC His contributed almost 100 percent of the noncarcinogenic risk. The soil COPC His were
approximately three to four orders of magnitude less than unity.

6.4.7. Risk Characterization

Tables 5 and 6 present the range of potential carcinogenic and noncarcinogenic risks associated with Area B,
respectively. The lowerbound values represent CTE values, while the upperbound values represent RME values.
These ranges indicate the uncertainties associated with Area B risks and provide information on the
sensitivity of each exposure scenario to the values of its numerical parameters.

6.5. Summary

The risk assessment performed for OU 1, Area B, has provided estimates of potential relative risk for the
future farmer resident and for future worker exposure to groundwater and soils. The scenarios that were
developed are conservative and hypothetical; relative risks determined for these can be interpreted more
accurately by considering the assumptions in the calculations.

For the future farmer resident, the total RME carcinogenic risks to the child and adult from all chemicals,
radionuclides, and pathways are 2 and 5 excess cancers in 10,000 persons exposed, respectively. The combined
overall RME adult and child risk may be of potential concern because it lies outside the upperbound value of
the EPA target carcinogenic risk range of 1x10-6 to 1 xlO-4. The majority of the carcinogenic risk comes
from PCE and trichloromethane.

Radium-226 and thorium-228 were the only daughter product radionuclides with RME carcinogenic risks that
exceed 1x10-6 for the future farmer resident. The RME carcinogenic risk for thorium-228 was found to be
1x10-4 in soil, which is higher than the risks for all other chemicals and radionuclides detected in soil.
However, thorium-228 was detected at concentrate on levels equivalent to background.
-------
Table 5. Carcinogenic Risk Characterization Summary Table
Carcinogenic Risk Range (Lowerbound Value = CTE, Upperbound
Value = RME)
Chemical

Organic Chemicals

1,2-Dichloroethane
2,3,7,8-TCDD (Dioxins)
Aroclor-1248 (PCB)
Benzo(a)pyrene
Chlordane (alpha)
Tetrachloroethene
Tetrachloromethane
Trichloroethene
Trichloromethane
Vinyl chloride

Radionuclides

Actinium-227
Plutonium-238
Plutonium-239/240
Strontium-90
Tritium

CTE - central tendency exposure
RME - reasonable maximum exposure
TCDD - tetrachlorodibenzo-p-dioxin
Future Farmer
Resident (Adult +
Child)
8E-07 -
2E-06 -
7E-07 -
2E-06 -
3E-06 -
6E-05 -
5E-06 -
9E-06 -
4E-05 -
2E-05 -
3E-06 -
2E-06 -
2E-06 -
2E-06 -
2E-06 -
3E-06
8E-06
5E-06
IE-OS
2E-05
3E-04
2E-05
4E-05
1E-04
8E-05
2E-05
7E-06
IE-OS
IE-OS
IE-OS
Future Indoor
Industrial Park Worker
3E-07 -
4E-22 -
3E-10 -
9E-07 -
2E-05 -
2E-06 -
4E-06 -
2E-05 -
6E-06 -
9E-07 -
5E-07 -
7E-07 -
4E-08 -
5E-07 -
2E-06
2E-21
1E-09
4E-06
8E-05
8E-06
2E-05
7E-05
3E-05
5E-06
2E-06
4E-06
2E-07
3E-06
Future Outdoor
Industrial Park
Worker
7E-08
3E-07
9E-08
2E-07
4E-07
IE-OS
6E-07
1E-06
2E-06
2E-06
9E-07
5E-07
7E-07
4E-08
5E-07
- 4E-07
- 2E-06
- 8E-07
- 2E-06
- 2E-06
- 7E-05
- 3E-06
- 5E-0§
- IE-OS
- IE-OS
- 5E-06
- 2E-06
- 4E-06
- 2E-07
- 3E-06
-------
Table 6. Noncarcinogenic Risk Characterization Summary Table
Chemical

Organic Chemicals

1,2-cis-Dichloroethene
1,2-Dichloroethane
Chlordane (alpha)
Tetrachloroethene
Tetrachloromethane
Trichloroethene
Trichloromethane
Noncarcinogenic Hazard Index Range (Lowerbound Value = CTE,
Upperbound Value = RME)
Future Farmer
Resident (Adult +
Child)
5.3E-01
5.2E-01
2.3E-01
1.4E+00
2.0E+01
5.6E-01
1.2E-01
- 1.1E+00
- 8.2E-01
- 1.4E+00
- 3.0E+00
- 3.1E+01
- 1.1E+00
- 2.4E-01
Future Indoor
Industrial Park Worker
5.5E-02
2.6E-01
3.7E-02
2.1E-01
9.9E+00
6.8E-02
- l.OE-01
- 4.1E-01
- 5.7E-02
- 3.5E-01
- 1.5E+01
- 1.2E-01
Future Outdoor
Industrial Park Worker
5.5E-02
2.2E-01
3.7E-02
2. IE. 01
8.6E+00
6.8E-02
- l.OE-01
- 3.7E-01
- 5.7E-02
- 3.5E-01
- 1.4E+01
- 1.2E-01
1.3E-02 - 2.5E-02
1.3E-02 - 2.5E-02
CTE - central tendency exposure
RME - reasonable maximum exposure
-------
His that exceed unity indicate that the chemical may cause adverse health effects to exposed individuals. As
a rule, the greater a chemical HI exceeds unity, the greater the level of potential concern. For the future
onsite resident scenario, tetrachloromethane and PCE pose the most significant noncarcinogenic risks, with
overall RME His 3 to 31 times greater than unity. Since the sum of all COPC RME and CTE His are 24 to 39
times greater than unity, exposure to all COPCs could produce adverse health effects for the potential future
residential farmer.

For the future indoor industrial park worker, the overall probability of cancer occurrence was 2 excess
cancers in 10,000 persons exposed (RME) and 5 excess cancers in 100,000 persons exposed (CTE). PCE,
chlordane (alpha), 1,2-dichloroethane, tetrachloromethane, trichloromethane, vinyl chloride, TCE,
actinium-227, plutonium-238, plutonium-239/240, and tritium had RME risk levels exceeding 1x10-6. The
majority of carcinogenic risk contribution is from PCE and trichloromethane. The overall indoor worker RME
risk may be of potential concern because it exceeds the USEPA target risk range of 1x10-6 to 1x10-4.

For the future outdoor industrial park worker, the overall probability of cancer occurrence was I excess
cancer in 10,000 persons exposed (RME) and 2 excess cancers in 100,000 persons exposed (CTE). PCE contributes
more than half of the carcinogenic risk. The overall outdoor worker RME risk may be of potential concern
because it lies at the upperbound limit of the USEPA target risk range.

Thorium-228 was the only daughter product radionuclide with RME and CTE carcinogenic risks that exceeded
1x10-6 for both the future indoor and outdoor workers. The future indoor and outdoor worker RME carcinogenic
risks for thorium-228 were both found to be 2x10-5 in soil; these risk levels are significantly higher than
the risks for all other chemicals and radionuclides detected in soil. However, thorium-228 was detected at
concentration levels eguivalent to background.

Tetrachloromethane is the only COPC that had RME and CTE His exceeding unity for both the future indoor and
outdoor industrial park worker scenarios. Without tetrachloromethane, the overall RME and CTE His are
approximately egual to or less than unity for the future indoor and outdoor workers.

The risks to future indoor and outdoor workers are based on chemical and radionuclide concentrations in
groundwater and soil within and directly adjacent to the sanitary landfill in Area B. The future worker
scenarios assume that exposures take place within Area B and that the drinking and domestic water supply is
exclusively from Area B.

The contaminants of concern (COCs) that are the focus of remedial action efforts are defined as COPCs with
either risks that exceed the minimum acceptable levels or risks that provide a significant contribution to
the overall risk in any one of the exposure scenarios. A COPC provides a significant contribution to the
overall risk if its hazard index exceeds 0.1 or its carcinogenic risk exceeds 1 xlO-6. Based on these
criteria, the COCs delineated by the OU 1, Area B, risk assessment for the resident scenario are the
following:

For groundwater:

1,2-Dichloroethane.
- 1,2-cis-DCE.
Benzo(b)fluoranthene.
Chlordane (alpha).
- PCE.
Tetrachloromethane.
- TCE.
Trichloromethane.
Vinyl chloride.
- Actinium-227.
- Plutonium-238.
- Plutonium-239/240.
- Radium-226.
Tritium.
-------
For soil:

2, 3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (dioxins) .
- Aroclor-1248 polychlorinated biphenyl (PCB).
Benzo(a)pyrene.
- Plutonium-238.
Strontium-90.

6.6. Additional Considerations

6.6.1. Ecological Risk

An evaluation of the potential ecological impacts of OU 1 was not conducted. The ecological risk assessment
will be performed on a site-wide basis during the OU 9 Site-Wide RI. The Mound Plant ecological risk
assessment will be performed in conjunction with the site-wide ecological assessment. The site-wide
ecological risk assessment will be based on data collected as part of the OU 9 RI, along with the information
obtained from the site-wide ecological assessment and other studies that have evaluated ecological conditions
around the Mound Plant facility. The issue of ecological impacts will be addressed in the final
determination for the site as a whole.

6.6.2. Immediate Points of Exposure

The most immediate point of exposure for contaminants originating in OU 1 also lies within the confines of OU
1 -the system of plant production wells. Production well was taken offline due to increasing levels of VOCs
in the discharge water. Production well 3 is now the primary source of process and potable water for the
plant. Production well 2 is pumped as reguired to provide a supplemental source of plant water,

6.7. Risk Assessment for the Selected Industrial Future Use Scenario

The preceding sections discussed the Baseline Risk Assessment-that is, a measure of the risks posed by the
site if no remediation took place. To select a remedy, a realistic future use scenario was determined to
help define cleanup goals. It has been agreed among the USEPA, OEPA, and DOE that the appropriate land use
for OU 1 is industrial. Offsite, the appropriate lard use remains residential. Thus, the context for onsite
soil remediation is that of an industrial park, with no onsite groundwater use or standards. By the same
token, the offsite contamination (limited to he groundwater pathway) must be protected to residential use
standards. The point of compliance is established outside the roadways that bound the former waste disposal
areas to the south and west. The assessment of risk expected under this future use scenario is discussed
below.

The risk assessment for OU 1 addressed future public health risks, defining the performance reguirements that
remedial actions would meet. The conceptual pathway model is shown in Figure 5. This risk assessment focused
on the exposure of hypothetical future site workers to soil contamination through inhalation, incidental
ingestion, external exposure to radiation emitted from radionuclides in soil, or dermal contact with the soil
by an onsite industrial worker.

The results of the risk assessment of the future outdoor worker show tha two of the COPCs were found to have
RME lifetime excess cancer-risks above 1x10-6. 2,3,7,8-TCDD and benzo(a)pyrene each had an estimated excess
cancer risk of 2x10-6. The combined carcinogenic risk is 4x10-6. Because the NCP specifies a target cancer
risk range of 1x10-4 to 1 xlO-6, and because this risk is already near the lower end of this range, the soil
pathway does not need further consideration. For noncarcinogens, the HI was less than one for soil,
indicating that noncarcinogenic health effects are not of concern.

The risk assessment also evaluated risks associated with future potential offsite residential use of
groundwater. The risks could result from direct exposure to contaminants by groundwater ingestion, ingestion
of groundwater-irrigated produce, and dermal contact and if inhalation of VOCs while showering with
groundwater. The analysis dealt with all the COCs. Results of the analysis are shown
in Table 7.
-------
Table 7. Summary of Risk for OU 1 (Soil and Groundwater) and Contaminants with Greatest Risk Contribution
Carcinogenic Risk

Resident Farmer or
Residenta

Adult

Child
Industrial Worker
(Indoor)

Industrial Worker
(Outdoor)

Noncarcinogenic HI

Resident Farmer or
Residentb
(Indoor)

Industrial Worker
(Outdoor)
Overall Risk
RME CTE
5 x 10-4

1 x 10-4
2 x 10-4
1 x 10-4
15
1 x 10-4

3 x 10-5
5 x 10-5
2 x 10-5
Adult
Child
lustrial Worker
17
19
16
11
12
10
Percent of
Exposure Due to
Ingestion and
Inhalation
83
80
83
(Inhalation and
Dermal)
96
98
95
(Inhalation)
Percent of Risk
via Groundwater
Pathways
96
COG Effect
100
95
100
COG with
Greatest Effect
Tetrachloroethene
Trichloromethane
Tetrachloroethene

Trichloromethane
Tetrachloroethene
Tetrachloromethane
100
100
Tetrachloromethane
Tetrachloromethane
RME
CTE
2 x 10-4 6 x 10-5
(Adult + Child) (Adult + Child)
1 x 10-4
(Adult + Child)

8 x 10-5

7 x 10-5
7 x 10-5
31
(Adult + Child)
15
14
aAlthough the resident farmer scenario includes more exposure pathways than the
additional risk for carcinogens.
bAdditional pathways for resident farmer collectively contribute less than 0.1%

COG - contaminant of concern
CTE - central tendency exposure
HI - hazard index
RME - reasonable maximum exposure
resident these pathways collectively contribute less than 0.5%

additional risk for noncarcinogens.
4 x 10-5
(Adult + Child)

2 x 10-5

2 x 10-5
1 x 10-6
20
(Adult + Child)
10
-------
Ingestion/inhalation contribute almost all of the risk; groundwater is the host important exposure medium (90
to 100 percent of each category). PCE had the highest overall carcinogenic risk in each exposure scenario;
tetrachloromethane had the highest noncarcinogenic HI 80 to 90 percent of the contribution in each category).
Because groundwater would contribute most of the carcinogenic and noncarcinogenic risks, it is the focus of
the remedial efforts.

6.8. Remedial Action Objectives

Remedial action objectives are descriptions of how the remedial actions will protect human health and the
environment and achieve the remediation goals.

6.8.1. Soils

To protect human health, the remedial action objective will be to prevent or reduce infiltration and
migration of contaminants that would result in groundwater contamination in excess of remediation goals.
Additionally, soil contaminants should not lead to an aggregate excess cancer risk greater than 1x10-5 or an
HI greater than one for occupational exposures.

6.8.2. Groundwater

To protect human health, the remedial action objective will be to prevent ingestion of water with contaminant
concentrations in excess of remediation goals (1x10-4 aggregate cancer risk for chemical risk and
radiological risk combined). To protect environmental health, the objective will be to control or reduce (to
remediation goals) the contaminant concentrations in the aguifer adjacent to OU 1. The preliminary
remediation goals for the groundwater medium are shown in Table 8. This will prevent contaminant movement
into the BVA and ensure that the BVA remains a safe drinking water source. The specific cleanup level of each
contaminant is based on federal primary drinking water standards (40 CFR 141) and the limits of analytical
capability to measure, as discussed in the FS. The point of compliance for groundwater is outside (south and
west) of the road bounding the site sanitary landfill,
as identified in 2 May 1994 correspondence (Attachment B).

7. DESCRIPTION OF ALTERNATIVES

The alternatives analyzed for OU 1 are discussed below. Detailed descriptions of the alternatives are
provided in the OU 1 FS.
-------
Table 8. Preliminary Remediation Goals
Lifetime
Constituent

Actinium-227c
Chlordane(alphe)
1,2-Dichlorosthane
1,2-c/s-Dichloroethene
Plutonium-238c
Plutortium-239/240c
Tetrachloroethene
Tetrachloromethane
Trichloroethene
Trichlorornethane
Tritiumc
Vinyl chloride
Risk-base
PRGa Cg/L}
0.1
0.06
0.1
60
0.2
0.2
1
0.2
2
0.2
900
0.02
SDWA
MCL
Cg/L)
NLd
2
NL
70
15e
15e
5
5
5
100
20,000
2
Ohio Drinking Maximum
Water Rule Concentrationb
Cg/L)
NL
NL
NL
NL
NL
NL
NL
5
5
100
20,000
2
Cg/L)
1.
ND
ND
12
0.
0.
2.
ND
ND
14
4,220
3.
,6

,0536
,317
,5

,6
Estimated
Quantitation
Limit (•/g/L)

0.2
0.06
0.3
1.0
0.2
0.2
0.3
1.2
1.2
0.5
500
1.0
Proposed
PRG (• g/L)
2
0.06
0.1
60
0.2
0.6
5
0.2
2
2
3,000
1
Risk at
Proposed
PRG
2 x
1 X
1 X
HQ =
1 X
3 x
5 x
1 x
1 x
1 x
3 x
5 x
10-5
10-6
10-6
1
10-6
10-6
10-6
10-6
10-6
10-5
10-6
10-5
aRisk-based PRGs concentration from residential water use scenario. When a contaminant had both carcinogenic and
noncarcinogenic risks, the lower was chosen. Risk-based PRGs were calculated as shown below.
bValues listed are the maximum detected values outside of the remediation area (wells 71, 154, 155, 377, and 378).
cPicocuries per liter (pCi/L).
dThe proposed MCL for beta and photon emitters is 4 milliroentgen eguivalent in man (mrem) ede/yr with a screening level of
50 pCi/L.
eMCL listed is a proposed value for adjusted gross alpha.

MCL - maximum contaminant level
NL - not listed
ND - not detected
PRG - preliminary remediation goal
SDWA - Safe Drinking Water Act
• g/L - micrograms per liter
-------
Chemical Carcinogen Risk-based PRG (• g/L) -

Noncarcinogen Risk-based PRG (• /L)

Radionuclide Carcinogen Risk-based PRG (pCi/L) -
TR x BW x AT x 1000 • g/mg

EF X ED X ([VF x IRA x SFi] + [IRW x SFo] )

TR x BW x AT x 1000 • g/mg
EF x ED x [VF x IRA + IRW]
[ RfDi RfDo]

EF x ED x ([VF x IRA x SFi] + [IRW xSFo)
Where:

TR =
BW =
AT =
EF =
ED =
VF
IRA
IRW

SFi
SFo
RfDi
RfDo
Target risk (1 x 10-6 for carcinogens, hazard guotient of 1 for noncarcinogens)
Body weight (age-adjusted for carcinogens-59 kg, for noncarcinogens - 70 kg)
averaging time (25,550 days)
exposure freguency (350 days/year)
exposure duration (30 years)
volatilization factor (where applicable = 0.5)
inhalation rate (age-adjusted for carcinogens - 19 m3/day
ingestion rate of water (age-adjusted for carcinogens - 1
for noncarcinogens - 2 L/day)
inhalation slope factor (chemicals - kg-day/mg, radionuclides 1/pCi
oral slope factor (chemicals - kg-day/mg, radionuclides 1/pCi)
inhalation reference dose (kg-day/mg)
oral reference dose (kg-day/mg)
for noncarcinogens - 20 m3/day)
L/day,
-------
7.1. Common Elements

All alternatives now being considered for the site will include several common components. Each alternative
includes surface controls, the implementation of institutional controls to limit access to the
site, and long-term groundwater monitoring. Surface controls, such as grading and lining of existing
ditches, will manage the surface water runon and runoff and reduce infiltration. Reducing infiltration
will slow the rate at which contaminants migrate from the unsaturated soil into the groundwater.
Institutional controls will be designed to control land and groundwater use. Such controls can take the
form of access restrictions and fencing around the site to minimize contact with soils and deed restrictions
to prevent groundwater usage onsite and downgradient on property currently owned by DOE. The site is
currently fenced. Appropriate deed restrictions will be obtained at the time the facility is transferred.
The monitoring activities will be conducted to document the effectiveness of the selected remedy.

Alternatives 3 through 7 include extracting the groundwater for disposal brough the Mound Plant
NPDES-permitted outfall. This groundwater extraction will be effective a capturing contaminated groundwater
before offsite migration can occur.

7.2. Description of the Alternatives

The alternatives contain elements that range from limited action through capping, containment, and in situ
treatment. Descriptions of these elements are provided below. More detailed descriptions of the
alternatives are provided in the FS.

The no-action alternative (Alternative 1) involves no additional activities at the site.

The limited-action alternative (Alternative 2) consists only of the common elements
described above.

The collection-and-disposal alternative (Alternative 3) also en compasses extraction of
groundwater for disposal through the Mound Plant NPDES-permitted Outfall. Under this
alternative, the soil contamination would be left in place.

Under the alternatives incorporating a treatment option (Alternatives 4 through 7),
groundwater would be extracted and treated onsite to remove VOCs.

Under the capping alternatives (Alternatives 5, 7, and 9), a surface cap of low-permeability
soil would be placed on the ground surface above known waste disposal areas that could
be considered potential sources of groundwater contamination. The cap would be
designed for integration into the existing cap for the site sanitary landfill and surface
drainage structures so that erosion and infiltration would be minimized.

Under alternatives incorporating a subsurface barrier (Alternatives 6 and 7), groundwater
would be contained onsite with a low-permeability subsurface wall around the western and
southern perimeter of OU 1, which would be constructed by the slurry column technigue.
Groundwater within OU 1 would be extracted only at a rate sufficient to maintain a
hydraulic gradient across the containment barrier toward OU 1.

Under the in situ treatment alternatives (Alternatives 8 and 9), subsurface permeable
treatment walls composed of a mixture of iron shavings and sand would be installed in the
subsurface downgradient of the site. Slurry columns would serve to direct the flow of
groundwater toward the treatment walls and minimize movement of groundwater offsite.

8. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES

This section presents a detailed analysis of the alternatives that were considered. Each alternative is
evaluated in detail using nine CERCLA evaluation criteria, which are categorized into the following three
criteria groups:
-------
Threshold Criteria

Overall protection of human health and the environment addresses whether a remedy
provides adequate protection of human health and the environment and describes how
risks posed through each exposure pathway are eliminated, reduced, or controlled
through treatment, engineering controls, or institutional controls.

Compliance with applicable or relevant and appropriate requirements (ARARs) addresses
whether a remedy will meet all of the ARARs or other federal and state environmental
laws and/or justifies a waiver on the basis of technical impracticability.

Primary Balancing Criteria

Long-term effectiveness and performance refers to expected residual risk and the ability
of a remedy to maintain reliable protection of human health and the environment over
time, once cleanup goals have been met.

Reduction of toxicity, mobility, or volume through treatment may be used as the
performance measure of the treatment technologies.

Short-term effectiveness addresses the period of time needed to achieve protection.
Short-term effectiveness also considers any adverse impacts on human health and the
environment that may be posed during the construction and implementation period until
cleanup goals are achieved.

Implementability is the technical and administrative feasibility of remedy, including the
availability of materials and services needed to implement a particular option.

Cost includes estimated capital, operations, and maintenance costs expressed as net
present worth costs.

Modifying Criteria

State/support agency acceptance reflects aspects of the preferred alternative and other
alternatives that the support agency favors or to which the agency objects, as well as
any specific comments regarding state ARARs or the proposed use of waivers. The
assessment of state concerns may not be complete until after the public comment
period on the RI/FS and Proposed Plan is held.

Community acceptance summarizes the public's general response to the alternatives
described in the Proposed Plan and in the RI/FS, based on public comments received.
Like state acceptance, evaluations under this criterion usually will not be completed
until after the public comment period is held.

The evaluation of alternatives is summarized in Table 9; cost detail is provided in Table 10. This section
profiles the performance of the selected remedy against the remedial evaluation criteria, noting
how it compares to the other options under consideration. Because the no-action and institutional controls
alternatives, by themselves, do not protect human health and the environment, they are not considered an
option for this site.

8.1. Threshold Criteria

To be considered a viable option, a remedial alternative must meet the threshold criteria or, in the case
of compliance with ARARs, justify a waiver of a particular ARAR.

8.1.1. Overall Protection
-------
All of the alternatives except 1 and 2 would provide adequate protection of human health and the environment
by eliminating, reducing, or controlling risk through treatment, engineering controls, or
institutional controls.

8.1.2. Compliance with ARARs

The chemical-specific and action-specific ARARs are presented in Attachment B. All alternatives (except the
no-action and institutional controls alternatives) were designed to meet all of the ARARs. Under the
no-action and institutional controls alternatives, ARARs would be exceeded at the point of compliance. All
remaining alternatives would meet their respective ARARs. The selected remedy treats VOC concentrations in
the discharge water from the remediation system and will, in particular, comply with the Chronic Freshwater
Criteria ARARs.

8.2. Balancing Criteria

Once the threshold criteria are satisfied, the balancing criteria are used to weigh the relative merits of
various alternatives. The issues concerning the balancing criteria are displayed in Table 9.
-------
Table 9. Summary of Remedial Action Alternative Comparison

Alternative
1
2
3
4
5
6
7

8
9

Short Title
No action
Institutional
Collect/
disposal
Collect/treat/
disposal
Collect/treat/
disposal/cap
Contain/ collect/
treat /disposal
Contain/ collect/
treat /disposal/
cap
In situ
groundwater
treatment
In situ
groundwater
treatment /cap

Complies
With
ARARs
No
No
Yes
Yes
Yes
Yes
Yes

Yes
Yes

Short-term
Effectiveness
No
No
Adeguatea
Adeguatea
Adeguateb
Adeguateb
Adeguateb

Adeguateb
Adeguateb

Long-term
Effectiveness
No
No
Yes
Yes
Yes
Yes
Yes

Yes
Yes
Protects
Human
Health and
the
Environment
No
No
Adeguate
Adeguate
Adeguate
Adeguate
Adeguate

Adeguate
Adeguate
Reduces
Toxicity,
Mobility,
or
Volume
No
No
Yes
MV
Yes
TMV
Yes
TMV
Yes
TMV
Yes
TMV

Yes
TMV
Yes
TMV

Implementability
Easy
Easy
Less difficult
Less difficult
Less difficult
Moderately
difficult
Moderately
difficult

More difficult
More difficult

Total Cost
90
$ 3,980,000
$ 262,000c
$ l,740,000c
$ 2,390,000c
$ 2,650,000c
$ 3,300,000c

$ l,980,000c
$ 2,630,000c
a Quicker implementation when compared to other alternatives.
b Longer construction time when compared to other alternatives.
c This total cost is in addition to the total cost shown for Alternative 2 (common cost).

ARARs - applicable or relevant and appropriate reguirements
MV - mobility and volume
TMV - toxicity, mobility end volume
-------
Table 10. Summary of Detailed Cost Analysis
Annual
Operation and
Maintenance
Present Value of
30-year
Operation and
Total Present
Alternative Total Capital
Number Short Title Costa
1
2

3
4
5
6
7
8
9
No action
Institutional
Each of the following entries is IN
Collect /disposal
Collect/ treat /disposal
Collect/ treat /disposal /cap
Contain/collect/treat/disposal
Contain/collect/treat/disposal/cap
In situ groundwater treatment
In situ groundwater treatment/cap

139,
ADDITION
$
$
$
$ 1,
$ 1,
$ 1,
$ 1,
205,
567,
857,
330,
620,
650,
940,
$ 0
000
TO the
000
000
000
000
000
000
000
without
Common Costa

$
cost shown

$
$
$
$
$
$

201,
for
$ 3,
61,
80,
69,
88,
17,
36,
$ 0
000
line 2
000
000
000
000
000
000
000
Maintenance without
Common Costa

$ 3,840,
(Alternative 2) .
$ 57,
$ 1,170,
$ 1,530,
$ 1,320,
$ 1,680,
$ 325,
$ 688,
$ 0
000

300
000
000
000
000
000
000
Value without
Common Cos"

$ 3,980

$ 262
$ 1,740,
$ 2,390
$ 2,650
$ 3,300
$ 1,980
$ 2,630
$ 0
,000

,000
OOOb
,000
,000
,000
,000
,000
a Represents the common cost used in each cost estimate.
b Represents highest likely cost for treatment technology.

NOTE: Figures rounded to three significant digits after computations completed.
-------
8.2.1. Short-Term Effectiveness

Alternatives 5, 7, and 9 provide the greatest short-term effectiveness because, immediately after
installation, the surface cap would prevent contact with contaminated soils. Some dust generation is
expected during installation of the cap; however, this risk could be easily reduced by dust control methods
and worker protection. The cap would also rapidly reduce leachate movement from the
unsaturated zone into the groundwater.

Alternatives 3, 4, 6, and 8, which do not include a surface cap but do include a fence around Area B, would
have little short-term effectiveness because contact with contaminated soils would not be completely
prevented. Potentially, onsite workers would be exposed to contaminated soils and the community could
potentially be exposed to COCs through airborne dust.

Environmental impacts common to all alternatives include disturbance of biota in the construction areas.
However, these would not be significant environmental impacts.

8.2.2. Long-Term Effectiveness and Permanence

Alternatives 7 and 9 provide the highest degrees of long-term effectiveness and permanence because they use a
subsurface containment system (slurry columns) to passively reduce offsite movement of contaminated
groundwater. Alternative 7 also employs groundwater recovery wells to extract contaminated groundwater from
Area B and to ensure a hydraulic gradient toward Area B. Groundwater recovery wells would be effective over
the long term at fulfilling these tasks. The permanence of these alternatives would also be considered high
because, once the PRGs are met, groundwater contamination would remain onsite. These alternatives also use a
surface cap to passively reduce leachate movement from the unsaturated zone. This technology would
contribute to the high degree of effectiveness and permanence of these alternatives due to the resultant
decrease in contaminant flux from the unsaturated zone.

Alternatives 6 and 8 also employ subsurface containment systems (slurry columns) around Area B. However,
because these do not implement a surface cap to control contaminant flux from the unsaturated zone, their
permanence would be considered less than Alternatives 7 and 9.

Alternatives 3, 4 and 5, which utilize groundwater recovery wells but no subsurface containment, would be
less effective at preventing offsite movement of contaminated groundwater. Even if properly monitored and
adjusted according to changing hydrogeologic conditions, a small amount of groundwater could potentially not
be captured if one or more recovery wells were shut down for maintenance.

8.2.3. Overall Protection of Human Health and the Environment

Alternatives D, 7, and 9 provide adequate protection of human health and the environment by reducing the risk
of soil contact and contaminated groundwater ingestion. Alternatives 3, 4, 6, and 8 reduce risk of
contaminated groundwater ingestion but provide minimal reduction of soil contact risk.

Alternative 1 (no action) provides no protection of human health and the environment. Alternative 2 provides
minimal reduction of the risk of contact with soil. Alternative 2 also provides some reduction
of risk through groundwater ingestion onsite, but there is some uncertainty about the prevention of offsite
groundwater ingestion.

8.2.4. Reduction of Mobility, Toxicity, and Volume Through Treatment

All alternatives except 1, 2, and 3 reduce the mobility, toxicity, and volume of contaminated groundwater by
employing UV/oxidation water treatment technology prior to its discharge through the NPDES-permitted outfall.
This technology is reliable with proper operation rand maintenance.

Alternatives 1 (no action) and 2 (institutional controls) do not reduce mobility, toxicity, or volume of
contaminated groundwater through treatment. Alternative 3 reduces only contaminant volume and
mobility in the groundwater by implementing groundwater extraction.
-------
8.2.5. Implementability

Technically, Alternative 2 would be the easiest to implement because it only involves construction of a
fence. However, this alternative would be the most difficult to implement administratively because of
uncertainties involving acquisition of land or water rights to prevent groundwater ingestion.

Alternatives 3, 4, and 5 could be implemented using standard construction techniques and practices. The water
treatment technology required in Alternatives 4, 5, 6, and 7 is not widely used but, because it has been put
into practice at several sites and is relatively uncomplicated to operate, it should be readily
implementable.

Alternatives 5, 7, and 9, which involve the surface cap, would be less implementable than their counterparts
that do not include a surface cap (Alternatives 4, 6, and 8). To make augmentation of the existing cap
feasible, the low-permeability soil option was chosen since it was the best match to the existing cap and
could be used to extend the cap over the desired areas with less disruption to the current containment
system. Given the steep sides of the existing landfill, however, an added degree
of difficulty exists in the design and implementation of the surface cap extension.

Alternatives 6 and 7, which involve construction of 8 subsurface barrier with slurry columns around Area B,
would not be as readily implementable as the previous alternatives. Prior to slurry column installation, a
soil-boring program for contaminant sampling and geotechnical testing must be conducted. The slurry column
installation would then be implemented using common construction practices.

Alternatives 8 and 9, which involve subsurface barriers and a subsurface permeable treatment wall, would be
less implementable than Alternatives 6 end 7 because treatability studies would be required to design the
permeable treatment well. The slurry column construction for this alternative would be the same as described
above.

9. SEIiECTED REMEDY

The selected remedy for controlling contamination from the soils and groundwater at OU 1 is Alternative 4 -
Collection, Treatment, and Disposal of Groundwater. As discussed previously, the common elements of surface
water controls, institutional controls to limit site access, and long-term groundwater monitoring will be
part of the remedy as well. Based on groundwater studies conducted during the FS, it is currently envisioned
that the collection (groundwater extraction) system will consist of two wells pumping at a combined rate of
45 gallons per minute. Additional groundwater modeling will be conducted during the remedial design phase,
which will establish optimum location and pumping rates for the extraction wells. Some changes may be made
to the remedy as a result of the remedial design and construction process. Such changes, in general, will
reflect modifications resulting from the engineering design process.

Based on current information, this alternative would meet the USEPA remedial evaluation criteria. The
alternative meets the threshold criteria (is protective of human health and the environment and satisfies
all the ARARs) and satisfies the primary balancing criteria (short- and long-term effectiveness; reduction
of toxicity, mobility, or volume; and implementability) for the least cost. Because it reduces toxicity
and volume and controls mobility, the alternative also protects the Mound Plant production wells. The
preferred alternative would be effective in capturing contaminated groundwater beneath the OU 1 site before
it migrates offsite. The groundwater pump-and-treat system will reduce the contaminant mass in the
subsurface and will continue to operate until groundwater meets the Preliminary Remediation Goals specified
in Table 8. It is difficult to predict how long this will take, but for costing purposes, it was assumed the
system would operated for a period of 30 years. The treatment system specified for this site could
efficiently remove the VOCs to the preliminary remediation goals listed in Table 8. All extracted groundwater
would be treated to levels that will comply with the requirements of the Mound Plant NPDES Permit.

The contemplated treatment system will primarily consist of a unit designed to remove VOCs from the water
prior to discharge. Final determination of all required treatment will be made as part of the detail design.
There are several potentially viable treatment trains for VOCs, including cascade aeration, UV oxidation, and
conventional air stripping; all offer the possibility of adequate treatment. Additionally,
-------
the CERCLA process allows for and promotes the use of innovative technologies whenever potentially
practicable and cost-effective. Final selection of technologies will be mad during remedial design, when any
of these systems may be determined to be optimal. Cascade aeration, as well as the other treatment trains,
constitutes best available treatment.

Thus, the selected remedy-collection, treatment, and disposal-will provide a cost-effective remedial option
that is easy to implement and that will adeguately protect human health and the environment.

Following issuance of the ROD, three kinds of changes that reguire documentation can be made to the
selected remedy. These are as follows:

Minor changes that reguire differences to be documented in the post-ROD file.

Significant changes that reguire the development of an explanation of significant
differences for inclusion in the Administrative Record. Significant changes are those that
modify or replace a component of the selected remedy.

Fundamental changes that reguire the development of a ROD amendment and, thus,
additional public comment. Fundamental changes are changes of the selected remedy that
do not reflect the ROD with regard to scope (e.g., overall approach), performance, or cost.

At the time DOE proposes the specific treatment technology to be used, DOE, in consultation with USEPA and
OEPA, will determine whether changes need to be made in the ROD end will implement the specified modification
procedures.

10. STATUTORY DETERMINATIONS

The selected remedy protects human health and the environment, complies with federal and state reguirements
that are legally applicable or relevant and appropriate (ARAR) to the remedial action, and
is cost-effective. A list of ARARs that will be attained by the selected remedy, along with the "To Be
Considered" (TBC) item that was used, is provided as Attachment B. In implementing the selected remedy, DOE,
USEPA, and OEPA have agreed to consider a procedure that is not legally binding. In implementing the
selected remedy, DOE, USEPA, and OEPA have agreed to consider as a TBC the OEPA policy on wastewater
discharge resulting from cleanup of response action sites contaminated with VOCs.

This remedy uses permanent solutions and alternative treatment technologies to the maximum extent practicable
for this site, end satisfies the statutory preference for treatment as a principal element of
the remedy. While the remedy calls for treatment of contaminated groundwater, treatment of soil at the site
was not found to be practicable. The fact that the source of contamination is diffuse and no substantive
onsite soil hot spots exist precludes a remedy consisting of excavation and treatment of
contaminants in soil.

Because this remedy will result in hazardous substances remaining onsite above health-based levels, a review
will be conducted within 5 years after commencement of the remedial action to ensure that the remedy
continues to provide adeguate protection of human health and the environment.

11. DOCUMENTATION OF SIGNIFICANT CHANGES

The OU 1 Proposed Plan was released for public comment in November 1994. The Proposed Plan identified
Alternative 4 (Collection, Treatment, and Disposal) as the preferred alternative for groundwater remediation.
DOE reviewed all written and verbal comments submitted during the public comment period. Upon review of
these comments, it was determined that no significant changes were necessary to the remedy as originally
identified in the Proposed Plan.
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RESPONSIVENESS SUMMARY

CONTENTS

RESPONSIVENESS SUMMARY 50

1. OVERVIEW 50

2. BACKGROUND ON COMMUNITY INVOLVEMENT 50

3. SUMMARY OF PUBLIC COMMENTS RECEIVED DURING PUBLIC COMMENT PERIOD AND
DOE RESPONSES 52
3.1. Summary and Response to Local Community Concerns 52
3.2. Comprehensive Response to Specific Legal and Technical Questions ... 59

4. REMAINING CONCERNS 59
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RECORD OF DECISION

OPERABLE UNIT 1

AREA B, MOUND PLANT, OHIO

June 1995

RESPONSIVENESS SUMMARY

1. OVERVIEW

At the time of the public comment period (15 November 1994), DOE had identified a preferred alternative for
OU 1, Area B. The recommended alternative, as published in the Proposed Plan, consisted of collection,
treatment, and disposal of groundwater. The treated groundwater would be released to the Great Miami River.

Judging from the limited number of comments received during the public comment period, the citizens and other
interested parties did not guestion the overall remediation strategy. Comments were directed to the nature
and need for treatment, as well as the manner in which the treatment system would be operated.

These sections follow:

Section 2, Background on Community Involvement.

Section 3, Summary of Comments Received During the Public Comment Period and DOE Responses.

Section 3.1, Summary and Response to Local Community Concerns.

Section 3.2, Comprehensive Response to Specific Legal and Technical Questions.

Section 4, Remaining Concerns.

Attachment C, Community Relations Activities for OU 1, Area B.

2. BACKGROUND ON COMMUNITY INVOLVEMENT

Community reaction to Mound Plant has been mixed. Unlike most sites that handle nuclear material and
hazardous chemicals, Mound Plant does not sit in an isolated location. The plant can be seen from downtown,
schools, farm fields, parks, and homes. The backyards of a few Miamisburg residences end at Mound Plant's
fence. Also, Mound Plant has had a highly visible community image, with a long record of community service
and philanthropy. Historically, the majority of the local residents have viewed Mound Plant as no threat to
the community.

Community involvement for OU 1 has been integrated with community involvement activities for the Mound Plant
Site as a whole. The Mound Plant CERCLA Community Relations Plan, published in 1990, provided for soliciting
comment while informing the public about planned and ongoing actions. The public information activities are
carried out through guarterly CERCLA public meetings and by periodic publication of a newsletter, the
Superfund Update.

As the field investigation of OU 1 was completed, public information activities directed toward OU 1 were
initiated. Specific items are:

An update on the field investigation was included in the October 1993 Superfund Update.

The budget priorities for OU 1 and the balance of the CERCLA program were the subject
of a workshop at the October 1993 CERCLA public meeting.
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A briefing on the site conditions and environmental issues relating to OU 1 was presented
at CERCLA public meetings on 14 June 1993 and 22 September 1994.

The OU 1 RIR, containing results and interpretations of field investigations, was placed in
the public reading room in May 1994.

A brochure, Environmental Restoration at Mound, was published n July 1994 and included
a short description of OU 1. A brochure providing more detail on OU 1 was published in
September 1994.

A fact sheet announcing the availability of the FS and the Proposed Plan was published in
November 1994.

Public comments were solicited and received at a public hearing on 8 December 1994.
The transcript of that hearing is available in the public reading room.

In response to comments, a second fact sheet was published ir December 1994.

The public comment period remained open until 31 January 1995.

3. SUMMARY OF PUBLIC COMMENTS RECEIVED DURING PUBLIC COMMENT PERIOD AND DOE RESPONSES

The public comment period extended from 15 November 1994 through 31 January 1995. A public meeting and
hearing was held on 8 December 1994. Two comments were received at the hearing. Two sets of written comments
were received from technical advisors to Miamisburg Environmental Safety and Health (MESH). The state of
Ohio raised one additional technical issue.

3.1. Summary and Response to Local Community Concerns

1. Selection of Alternative 4 over Alternative 3.

At the 8 December 1994 public meeting for the OU 1 Proposed Plan, a question was raised concerning Table 1 on
page 9 of the Proposed Plan. The guestion concerned the apparent similarity of Alternatives 3 and 4, with
the exception of maximum total cost.

DOE Response: Table 9, in the ROD, updates and clarifies Table 1 by identifying the reduction of toxicity,
mobility, or volume of contaminants that each alternative addresses. Alternative 3 meets the
mobility and volume reduction statutory preference for selecting remedial actions (page 4-10 of the OU 1 FS).
It does not address toxicity reduction, which is also a statutory preference for selecting remedial actions.
Therefore, DOE, in consultation with the USEPA and OEPA, has determined that Alternative 4, which includes
treatment to reduce toxicity, is preferable. The reduction of toxicity, mobility, or volume for Alternative
4 is explained on page 4-14 of the FS.

Guidance from the OEPA indicates that wastewater discharges resulting from cleanup of response action sites
contaminated with VOCs need to be treated with the best available technology for toxicity reduction. The
state of Ohio believes that Alternative 3 does not meet those requirements.

The NCP (40 CFR 300) identifies two additional "modifying criteria," which are (1) state acceptance and (2)
community acceptance. Based on the state's position on Alternative 3, Alternative 4 was chosen as the
preferred alterative. This Responsiveness Summary incorporates an evaluation of community acceptance based
on public comments.

2. Compatibility with overall remedy for The Site.

At the 8 December 1994 public meeting for the OU 1 Proposed Plan, a question was raised whether the remedy
for OU 1 would help or hinder remedial action for the Site as a whole. The recommendation was made to "put
your arms around the whole project."
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DOE Response: DOE is ultimately concerned with a remedy for the Mound Plant CERCLA Site as a whole. The
Site has been broken down into separate OUs to facilitate the planning and investigation. OU 1 is the first
unit to be considered for final remedial action. The other OUs also likely will be considered one at a time
to maintain a reasonable rate of progress. However, each removal action, interim remedial action, or final
remedial action is evaluated to ensure that it s unlikely to interfere with any overall remedy for the
complete Site.

The selected remedy for OU 1 will withdraw groundwater from beneath an immediately adjacent to OU 1. A small
portion of the groundwater that now flows down the tributary valley and enters the BVA could be diverted into
the remediation wells. The effect of the remediation on the hydraulic performance of the plant production
wells is expected to be immeasurably small. Thus, the selected remedy is expected to be compatible with
potential remedial actions in other parts of the plant. Further, it should support or assist in controlling
migration of contamination thus directly supporting a range of alternatives. As other portions of the plant
are considered for remediation, DOE will reconsider this issue.

3. Peter Townsend, MESH Technical Advisor, stated, "I conclude that remedial alternative 4 is the most
reasonable alternative for clean-up of the landfill and overflow pond area. Alternative 4 will involve
ground water collection and treatment, and appears capable of preventing further contamination of groundwater
in the immediate area of the overflow pond and existing landfill."

Mr. Townsend went on to comment on the occurrence of 1,1,1-TCA in The BVA. He agreed with the assertion in
the RIR that OU 1 was not the source of this contaminant, but suggested that it could still be the result of
Mound Plant activities. He identified the NPDES 001 outfall pipe as a possible source, since it had
(formerly) been an unsealed, butted cement pipe. Mr. Town,send recommended that
consideration of this possible source be considered in the OU 1 FS or a future document.

DOE Response: This commentor agrees with the DOE selection of the remedial alternative presented in the OU 1
Proposed Plan. However, concern is raised regarding offsite contamination, which DOE has concluded is not
related to OU 1 or, in fact, to Mound Plant. The commentor misinterprets a statement on page 2-20 of the RIR
and concludes that VOC contamination was discovered and caused some private residences to be connected to
Miamisburg city water. The statement says that "In January 1988, residences that used groundwater from wells
0901, 0902, 0903, 0905, 0907, and 0908 (Figure 2.5 in the RIR) were connected to Miamisburg city water due to
local organic contamination." This group of wells was owned by the operator of a trailer park, who supplied
drinking water to the residents. This system met the definition of a community water system and was subject
to the Safe Drinking Water Act (SDWA) regulations. It is DOE's position that these residences did not
discontinue use of these wells as a result of VOC contamination originating from Mound Plant. The switch to
city water was caused, we believe, by the owner's difficulty and expense involved with the testing and
operating conditions reguired to comply with SDWA regulations. During 1986 to 1988, Mound Plant conducted at
least six separate sampling events for wells 0901 through 0908. No VOCs were detected in any of these
events; specifically, 1,1,1-TCA was not detected. This commentor also speculates that the source of the
alleged 1,1,1-TCA plume was the Mound Plant NPDES outfall 001 pipeline. To clarify the situation, Mound
Plant drawings and long-time employees were consulted. Drawings indicate that the pipeline is
12-inch-diameter vitrified clay pipe, of bell and spigot configuration, from west of Cincinnati-Dayton Pike
to the river. This configuration would reguire each
joint to be filled with mortar to allow proper alignment. As part of a site-wide program to upgrade sewer
lines, this pipeline was slip-lined with a continuous plastic liner in approximately 1980 to 1981. This was
done as a good management practice, not because of a known contamination problem. No VOC contamination has
been detected from the wells (0127, 0128, 0302, 0303, 0343, 0383) located due south of the 001 outfall pipe,
which confirms there is no VOC contamination as a result of possible leakage from the 001 discharge pipe.

4. Jeff Fisher, MESH Technical Advisor, provided the following comments:

a. No remediation goals (except ARARs were described for surface and ground water, surface and deep soil,
sediment and air. Clean up or treatment is fine, but goals need to be established and agreed upon by the
USEPA, OEPA, Mound, and Stakeholders. A clear assessment of the treatment system's ability to meet cleanup
goals is necessary. Without a target you are just "shooting arrows at a wall."
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DOE Response: All of these issues are addressed in the OU 1 FS, which was released for public review with the
Proposed Plan. Remediation goals were established and cleanup targets were agreed upon in extensive
discussions among Mound Plant, DOE, USEPA and OEPA.

b. Offsite contamination needs to be addressed and workable solutions discussed by the Mound, regulators,
and stakeholders. Environmental contamination extends beyond the boundaries of Mound.

DOE Response: Offsite issues are being addressed through the OU 9 (site-wide) RI/FS process, as well as
through additional OUs (such as the Miami-Erie Canal). Since conditions at OU 1 do not lead to offsite
contamination, it is not addressed in the current documents.

Mr. Fisher went on to address comments to the OU 1 RIR, which was placed in the reading room in May 1994.
Although not pertinent to the Proposed Plan, the comments and responses are provided below.

a. Please explain the concept of "background" as it pertains to cleanup of chemicals and radionuclides.
Is it US EPA policy to use background values obtained from the Mound site? How are these used or compared to
background values obtained from sites distant from the Mound?

DOE Response: Chemical and radiological background for the Mound Plant Site is being defined in a series of
data reports published as part of the OU 9 (site-wide) RI. The background data for surface soils were
published in 1994 (Background Soils Investigation Soil Chemistry Report, Technical Memorandum, Revision 2,
September 1994). This document is available in the public reading room. Background statements for
groundwater, surface water, and sediments are being prepared. All background will be based on data from the
vicinity of, but beyond the influence of, Mound Plant. Use of background data will be on a case-by-case
basis. No reliance on background was used in selecting the remedy for OU 1.
b. For toxicity values that reference the ECAO [Environmental Criteria and Assessment Office], please supply
written documentation showing the derivation of the toxicity value. Please state what year of HEAST tables
were cited. Are Heast tables prior to 1994 used?

DOE Response: Toxicity values were obtained from the USEPA, as cited in the text and Appendix J of the OU 1
RIR. No independent derivation of toxicity was made, so no additional documentation is available. HEAST
tables from 1993 were used, since this effort was completed in 1993.

c. There are several typographical errors, but the errors did not detract from the intent of the document.

DOE Response: Noted.

d. The overflow pond appears to be without adeguate analytical data and was not included in the risk
assessment. Without this added to the baseline risk assessment, the baseline risk assessment is inadeguate
and does not address all important pathways of exposure.

DOE Response: As discussed in the RIR, the overflow pond is part of the plant drainage system, which is
being studied as part of the OU 9 investigation. The limited data available suggest that the overflow
pond is not a significant direct source of contamination to the aguifer system. The pond water and sediment
are not highly contaminated, and the leakage through the liner is not anticipated to be significant. These
issues are addressed in sections 4.2 and 4.4.4 of the RIR. The pond is not an important pathway of exposure
for OU 1.

e. The documents pertaining to OU 1 need to be available to the public in draft form. This is a very
serious problem that needs to be corrected.

DOE Response: All documents are reviewed in draft by both regulatory agencies (USEPA and OEPA), who approve
the final versions prior to public release. This is consistent with CERCLA guidance.

5. The following written comments were received from an anonymous reviewer of the OU 1 Proposed Plan:

a. Are the Miami Erie Canal sediments the only potential source of tritium in the BVA?
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DOE Response: No. The canal is the major source, but small amounts of tritium have also been detected in
wells in the Old Burn Area and Old Landfill Area.

b. What proof do you have that Mound is the source of the VOC contamination presently detected in the BVA?

DOE Response: The highest levels of VOCs have been detected onsite in the OU 1 location. Historical Mound
well monitoring data also confirm this.

c. Are there any known current tritium sources that may eventually reach the BVA? Are there any known
current tritium sources that may reach the canal?

DOE Response: cl) Yes, under the SW Building. However, it is unlikely that the SW Building tritium source
will reach the BVA. c2) Yes, tritium reached the canal as a result of Mound discharging tritiated
plant water in the Mound drainage ditch that flows into the canal.

d. What are the tritium levels in the main hill seeps?

DOE Response: The highest levels are in the low 100s nanocurie per liter range. The seeps are not a threat
to the aguifer.

e. What historic maximum levels of VOCs were detected in the upstream aguifer (from the Mound Plant) during
a Mound sampling/analysis event or "other's" sampling/analysis event?

DOE Response: The observed levels of VOCs in the background wells (completed in the BVA) are as follows:

Range of Detected
Concentrations Mean of Concentrations
Chemical (• g/L) (• g/L)

1,1,1-TCA 0.46 - 2.3 0.53
1,2-cis-DCE 1.1 - 1.1 0.55
PCE 11. - 12. 2.21
Trichloromethane (chloroform) 0.50-0.57 0.30

f. What are the current levels of VOCs upstream from Mound Plant?

DOE Response: The OU 9 Groundwater Sweeps Report, dated January 1995, showed the following monitoring well
data:

Well 0118 0.68 • g/L 1,2-Dichloroethane
Well 0137 1.6/«g/L Trichloroethane
Well 0137 0.58 • g/L Trichloromethane (chloroform)
Well 0138 0.53 • g/L 1,2-Dichiorethene
Well 0138 6.0 • g/L Acetonitrile
Well 0138 0.58 • g/L Trichloromethane (chloroform)
Well 0138 9.9 • g/L Trichloromethane (chloroform)
Well 0327 2.3 • g/L 1,1,1-Trichloroethane
Well 0327 12.0 • g/L Tetrachloroethene
Well 0327 0.50 • g/L Trichloromethane (Chloroform)
Well 0328 1.1 • g/L 1,2-cis-Dichloroethene
Well 0328 9.0 • g/L Bis (2-Ethylhexyl) Phthalate
Well 0332 8.9/*g/L Dichloromethane (Methylene Chloride)

g. What ground water model was used to determine the contribution of VOC contamination from the Mound
historic landfill verses the historic upstream VOC contamination?
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DOE Response: For the VOCs, the Darcy Model was used.

h. How does the OU 4 canal remediation schedule, the OU 1 remediation schedule and the OU 2 remediation
schedule tie into one another?

DOE Response: Because OU 1 groundwater contamination is the reason the Mound site was put on the NPL, or
Superfund, OU 1 has been given a high priority for cleanup by the DOE. The OU 1 VOC contamination problem is
a result of past disposal practices in OU 1 and is not interactive with the other Mound Plant OU schedules.

i. Will all other known sources of VOCs be completely remediated prior to the implementation of the OU 1
Proposed Plan?

DOE Response: No. However, at this time no other plant VOC sources are impacting OU 1.

j. Do you plan to remediate OU 4 (the canal), contain the main hill seeps (OU 2), or remediate the VOC
contaminated soils in the landfill prior to remediating the aguifer?

DOE Response: jl) No. OU 2 and OU 4 are not affecting OU 1 (see response to h). J2) The site sanitary
landfill and overflow pond overlie most of OU 1, making large-scale excavation prohibitive.

k. What are the calculated risks (cancer) for the no-action alternative for OU 17

DOE Response: The highest overall risk for the onsite resident is 5x10-4.

i. What is the total cost for the OU 1 Proposed Plan implementation?

DOE Response: The estimated cost for the proposed remedy, collection, treatment, and disposal is $1,740,000.
This includes installation costs and annual operations and maintenance costs for an estimated 30-year
remediation cycle.

m. What long term ground water monitoring and sampling will be necessary after remediation is complete? Is
there sufficient Congressional budget available to support the long term monitoring work?

DOE Response: ml) Monitoring and sampling reguirements after OU 1 remediation is completed will be
determined based on USEPA groundwater regulatory guidance. m2) Budget provisions have been made for this
work, but this funding is subject to change.

n. What is the cost for the long term monitoring and sampling in the current five-year plan? How much will
the long term monitoring and sampling cost?

DOE Response: No long-term monitoring and sampling funding has been specifically identified in the OU 1
5-year plan. Costs for the long-term monitoring and sampling after OU 1 is remediated will be determined
based on USEPA groundwater guidance reguirements (see response to m).

o. Has OEPA and US EPA approved the proposed remedial actions based on risk concerns?

DOE Response: Yes. The Proposed Plan preferred alternative has been approved by both USEPA and OEPA.

p. What risk level is acceptable as a no action level by Ohio EPA for tritium b? for VOCs? for tritium
and VOCs based on levels found in the BVA?

DOE Response: The acceptable USEPA cancer risk levels are 1x10-4 to 1x10-6.

g. What risk level is acceptable as a no action level by US EPA for tritium? or VOCs? for tritium and
VOCs based on levels found in the BVA?

DOE Response: The acceptable USEPA cancer risk levels are 1x10-4 to 1x10-6.
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r. What levels of risk are necessary for the "no action alternative" to be approved by the Ohio EPA and US
EPA regulators assigned to oversee work at Mound? at WPAFB?

DOE Response: The acceptable USEPA cancer risk levels are 1x10-4 to 1x10-6.

3.2. Comprehensive Response to Specific Legal and Technical Questions

As part of its continuing review of the OU 1 FS and Proposed Plan, the OEPA and the Regional Air Pollution
Control Authority (RAPCA) examined the need for air-related permits for the remedy. These agencies suggested
that an application to and review by RAPCA are appropriate. Subseguent conversations and correspondence
confirmed that neither a permit application nor a design review is needed.

4. REMAINING CONCERNS

None.
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ATTACHMENT A

STATE CONCURRENCE LETTER

State of Ohio Environmental Protection Agency
STREET ADDRESS:
MAILING ADDRESS:
1800 WaterMark Drive
P.O. Box 1049
Columbus, OH 43215-1099
OH 43216-1049

May 22. t99s
TELE: (614) 644-3020 FAX: (614) 644-2329
RE: US DOE MOUND
OPERABLE UNIT 1
RECORD OF DECISION
CONCURRENCE LETTER
Columbus,
Mr. Valdas Adamkus
Regional Administrator
US EPA Region V
77 West Jackson Boulevard
Chicago, Illinois 60604-3590

Dear Mr. Admakus and Mr. Hamric:
Mr. J. Phil Hamric
Manager, Ohio Field Office
US Department of Energy
P.O. Box 3020
Miamisburg, Ohio 45343-3020
The Ohio Environmental Protection Agency (Ohio EPA) has received and reviewed the April
1995 Operable Unit 1 (OU1) Record of Decision (ROD) for the DOE Mound Superfund site in
Montgomery County.

The OU1 ROD is the first ROD to be completed for the operable units at the DOE Mound. This
remedial action is not the final remedial action for the DOE Mound site, but is intended to be a
final remedial action for OU1. Decisions regarding remedial actions for other portions of the site
are being addressed in other operable units, which will ultimately be considered in a Site-wide
Remedial Investigation and Feasibility Study, which are in progress. A decision on the final
remedial action for the DOE Mound Site will be nude in a subseguent decision-making process.

The OU1 ROD addresses groundwater contamination by preventing migration of contamination
(volatile organic compounds) toward the DOE Mound production well. The selected remedial
action will result in the minimization of exposure to potential receptors of the groundwater
contamination. The selected alternative includes the following components:

* Installation of two groundwater extraction wells within OU1, using
standard eguipment and procedures. Specifics regarding the design of the
extraction system will be determined in the Remedial Design.

* Treating the extracted groundwater to remove volatile organic compounds
and other constituents, as reguired, using cascade aeration, ultraviolet
oxidation, conventional air stripping, or other suitable treatment units
including innovative technologies which will achieve the remedial
objectives.
EPA 1613 (rev. 1/95)
George V. Voinovich, Governor

Donald R. Schreoarclus, Director
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Mr. Adamkus & Mr. Hamric

* Discharging the treated groundwater to the Great Miami River through the
existing plant NPDES outfall or a new outfall. Permit modifications may
be needed to accommodate the final design of the remedy.

The estimated present cost of the selected remedy is $706,000 in 1995 dollars. The estimated
annual present worth of operation and maintenance costs are $1,170,000 for a period of 30 years.

Ohio EPA concurs with the selected remedy based upon this review. Since, the selected remedy
does not inlvolve establishment or modification of the site sanitary landfill, Ohio Administrative.
Code 3745-27-07 is not considered to be Applicable or Relevant and Appropriate (AEAR),
although it would be a potential ARAR for other OU1 remedies.

Because this remedy may result in hazardous substances remaining Onsite above health-based
levels, a review will be conducted within five years after commencement of this remedial action to
ensure that the remedy continues to adeguately protect human health and he environment.

Sincerely,

Donald R. Schregardus
Director
DRS/klf
Jenny Tiell, Director's Office
Tim Fischer, USEPA Region V
Jeff Hurdley, OEPA Legal
Graham Mitchell, OEPA/OFFO
Jan Carlson, OEPA/DERR
Warren Shefatal, DOE MB
Oba Vincent, DOE MB
Art Kleinrath, DOE MB
Brian Nickel, OEPA/OFFO
Ruth Vandegrift, ODH
Ray Beaumier, OEPA/DERR
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ATTACHMENT B

ARARs TABLES

Table 1. State Chemical-Specific ARARs for OU 1
Prohibits emission of an air contaminant in violation of
Section 3704 or any rule, permit, order, or variance issued
pursuant to that section of the ORC.
Regulation Application

May pertain to any site where
emissions of an air contaminant occur
either as s preexisting condition of the
site or as a result of remedial activitie
Should be considered for virtually all
sites.
Implementation of the substantive
provisions of state air requirements as
ARARs is required by Section 121 (d) of
CERCLA.
A) Prohibits commingling low-level radioactive waste with
any type of solid, hazardous, or infectious waste.
B) He owner or operator of a solid, infectious, or
hazardous waste facility shall accept any radioactive
waste for trans fer, storage, treatment, or disposal.
which low-level
e to be
All surface waters of the state shall be free from:
A) Obj ectienable suspended solids.
B) Floating debris, oil, and scum.
C) Materials that create a nuisance.
D) Toxic, harmful, or lethal substances.
D) Nutrients that create nuisance growth.

Prevents degradation of surface water quality below
designated use or existing water quality. Existing instrearn
uses shall be maintained and protected. The most
stringent controls for treatment shall be required by the
director of the US EPA for all new end existing point source
discharges. Prevents any degradation of "State Resource
Waters."
Pertains to discharges to surface
waters as a result of remediation and tc
any omits surface waters affected by
site condition.
Pertains to discharges to surface water
as a result of remedial action and to
any surface water affected by site
conditions.
Surface water bodies subj ect to quality
criteria standards do not occur within all
1. Alternatives that involve discharge to
surface water will be addressed in action-
specific ARARs.
Water Quality Criteria/
3745-1-07 C
A) Presents the criteria for establishing non-thermal mixing
zones for point source discharges.
B) Presents the criteria for establishing thermal mixing
zones for point source discharges.
Pertains to discharges to surface
waters as a result of remedial action
and any surface waters affected by site
conditions.
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Table 1. (page 2 of 5)
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph
Particulate
Nondegradation
Policy/3745-17-05
Regulation Description
Pertains to any site that may emit
measurable guantities of particulate
matter (both stack and fugitive).
Consider for sites that will undergo
excavation, demolition, cap installation,
clearing and grubbing, incineration, end
waste fuel recovery.

ARAR
Air emissions may be involved as part of
the treatment in several of the
alternatives. Alternatives involving air
emissions will be coordinated with US EPA
and OEPA to ensure particulate emissions
are within acceptable limits.
Air emissions may be involved as part of
the treatment in several of the
alternatives. Alternatives involving air
emissions will be coordinated with US EPA
and OEPA to ensure particulate emissions
are within acceptable limits.
Evaluation of
Wastes/3745-52-11
A-D
Ground Water
Protection:
Applicability/
3745-54-90
Establishes circumstances under which an operator of a
hazardous waste facility must implement a groundwater
protection program or a corrective action program.
Pertains to all sites with land-based
hazardous waste unite (surface
impoundments, waste piles, land
treatment units, and landfills), including
existing land-based areas of
contamination.

Whenever hazardous constituents from
a regulated unit are detected at the
compliance point, or whenever
groundwater protection standards are
exceeded between the compliance
point and the downgradient facility
property boundary.
Any materials generated during
construction or implementation of remedial
actions win be evaluated to determine if
they are identifiable as a hazardous waste,
or if they are sufficiently similar to
hazardous wastes so that hazardous
waste management standards should be
applied.

Historic disposal of hazardous waste
occurred within OU 1. Groundwater
monitoring implemented as part of the
remedial alternatives will incorporate the
reguirements of the hazardous waste
regulations.

Exceedencee of groundwater protection
standards have been observed within
OU 1. Groundwater monitoring program is
ongoing; a program will be implemented
as part of a remedial alternative that will
follow reguirements of this ARAR.
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Table 1. (page 3 of 5)
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph

Maximum Contaminant
Levels for Inorganic
Chemicals/3745-81-11
A,B
Regulation Description
Presents maximum contaminant levels
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
ARAR

ARAR
Because of the potential impacts to the
EVA, this standard will be applied.
Maximum Contaminant
Levels for Organic
Chemicals/3745-81-12
A,B,C
Presents maximum contaminant
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
Because of the potential impacts to the
BVA, this standard will be applied.
Presents maximum Contaminent levels for turbidity.
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
Because of the potential Impacts to the
BVA, this standard will be applied.
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
Because of the potential impacts to the
BVA, this standard will be applied.
Maximum Contaminant
Levels for Radium-22 6,
-228, and Gross Alpha/
3745-81-15 A,B
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as s drinking
water source.
Maximum Contaminant
Levels for Bets Particle
and Photon
Radioactivity/
3746-81-16 A,B
Pertains to any site that has
contaminated surface or groundwater
this is either being used or has the
potential for being used as a drinking
water source.
Because of the potential impacts to the
BVA, this standard will be applied.
-------
Table 1. (page 4 of 5)
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph

Microbiological
Contaminant Sampling
and Analytical
Reguirements/
3745-81-21 A-B
Regulation Description
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
Turbidity Centeminent
Sampling and Analytical
Reguirements/
3745-81-22 A-B
Presents sampling and analytical reguirements for
turbidity.
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
Appropriate methods for monitoring
compliance with ARARs will be
coordinated with OEPA and USEPA.
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
Appropriate methods for monitoring
compliance with ARARs will be
coordinated with OEPA and USEPA.
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
Presents monitoring reguirements for radioactivity.
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
-------
Table 1. (page 5 of 5)
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph
Regulation Description
Pertains to any site that has
contaminated surface or groundwater
that is either being used or has the
potential for being used as a drinking
water source.
ARAR

ARAR
Provides criteria by which director may grant variance from
MCLs.
Pertains to any site which has
contaminanted ground or surface water
that is either being used, or has the
potential for use, as a drinking water
source.
If reguired, the remedy will comply
this provision.
Allows for the use of alternative treatment technigues to
attain MCLs.
Pertains to any site which has
contaminated ground or surface water
that is either being used, or has the
potential for use, as a drinking water
source.
If reguired, the remedy will comply
this provision.
ARAR - applicable or relevant and appropriate reguirement
EVA - Buried Valley aguifer
CERCLA - Comprehensive Environmental Response, Compensation, and Liability Act
MCL - maximum contaminant level
OEPA - Ohio Environmental Protection Agency
ORC - Ohio Revised Code
OU 1 - Operable Unit 1
USEPA - U.S. Environmental Protection Agency
-------
Table 2. Federal Chemical-Specific ARARa for OU 1

Regulatory Program Reguirement

CWA Acute CWA freshwater toxicity
ARAR

ARAR
Compliance is specifically
reguired by CERCLA § 121 (d)
where relevant and appropriate.
Will be applied except where
more appropriate standards exist.
For example, standards
specifically intended for
groundwater or drinking.
Safe Drinking Water Act
Compliance is specifically
reguired by CERCLA § 121 (d)
where relevant and appropriate.
Resource Conservation and Recovery Groundwater Protection Program for Hazardous Waste
Act Groundwater Monitoring "Regulated Units" (40 CFR 264 Subpart F).
Reguirements
Considered relevant and
appropriate because of historic
disposal of apparent hazardous
wastes.
ARAR - applicable or relevant and appropriate reguirement
CERCLA - Comprehensive Environmental Response, Compensation, and Liability Act
CWA - Clean Water Act
USEPA - U.S. Environmental Protection Agency
-------
Table 3. State Location-Specific ARARs for OU 1
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph
Regulation Description
Filling, grading, excavating, building, drilling or mining on
land where a hazardous waste or solid waste facility was
operated is prohibited without prior authorization form the
director of the OEPA.
Implementation of the substantive
provisions of state requirements relating
to intrusive activities at former disposal
Pertains to any site at which solid
waste has come to be located or will
be generated during a rememdial
action.
Solid wastes generated as part of the
remedy will be subj ect to this
requirement.
Hazardous Waste
Facility Environmental
Impact/3734 . 06
(D) (6) (c)
A hazardous waste facility installation and operation
permit shaft not be approved unless the facility is proven
to represent the minimum adverse environmental impact
considering the state of available technology, the nature
and economics of various alternatives, and other pertinent

(D)(6)(d). A hazardous waste facility installation end
operation permit shall not be approved unless it proves
that the facility represent the minimum risk of all of the
following:
(i) Contamination of ground and surface waters.
(ii) Fires or explosions from treatment, storage, or
disposal methods.
Pertains to all sites where hazardous
wastes are located and/or where
hazardous wastes will be treated,
stored, or disposed of. May function
as siting criteria.

Pertains to all sites
waste has come to be located and/or
at which hazardous will be treated,
stored, or disposed of. May function
While no permit is required, remedial
alternatives will be coordinated with the
USEPA end OEPA.
(D)(6)(g)(h). Prohibits the following location for treatment,
storage and disposal of acute hazardous waste:
(i) Within 2,000 feet of any residence, school,
hospital, j ail or prison.
(ii) Any naturally occurring wetland.
(iii) Any flood hazard area.
(iv) Within any state park or national park or
Water Use
Designations for
Southwest Ohio
Tributaries/3745-1-17
Pertinent if stress or stream segment
is onsite and is affected by site
conditions or if remedy includes direct
discharge. Used by DWQPA to
establish waste load allocations.
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Table 3. (page 2 of 2)
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph
Regulation Description
Water Use
Designations for Great
Miami River/
3745-1-21
Pertinent if stream or stream segment
is onsite and is affected by site
conditions or if remedy includes direct
discharge. Used by DWQPA to
establish waste load allocations.
Mandates that groundwater wells be:
A) Located and maintained to prevent contaminants from
entering the well.
B) Located to be accessible for cleaning and
maintenance.
Pertains to all groundwater wells on
the site that either will be installed or
have been installed since February
1975. Would pertain during the FS if
new wells are constructed for
treatability studies.

Pertains to sites in certain locations
that may emit or allow the escape of
particulates (both stack and fugitive).
Consider for sites that will undergo
excavation, demolition, cap installation,
clearing and grubbing, and incineration.
Fugitive dust emission controls may be
reguired during construction. Alternatives
involving air emissions will be coordinated
With USEPA and OEPA to ensure
particulate emissions are within
acceptable limits.
Pertains to sites within a restricted area
(within the boundary of a municipality
and a zone extending beyond such
municipality).
Disturbances Where
Hazardous or Solid
Waste Facility Was
Operated/
3745_27-i3 c
Prohibits any filling, grading, excavating, building, drilling,
or mining on land where a hazardous waste facility or
solid waste facility was operated without prior
authorization from the director of the USEPA. Special
terms to conduct such activities may be imposed by the
director to protect the public and the environment.
Pertains to any site where hazardous or
solid waste has been ,damaged, either
intentionally or otherwise. Does not
pertain to areas that have had one-time
leaks or spills.
Implementation of the substantive
provisions of state reguirements relating
to intrusive activities at former disposal
sites as ARARs is reguired by Section
121 (d) of CERCLA.
ARAR - applicable or relevant and appropriate reguirement
CERCLA - Comprehensive Environmental Response. Compensation, and Liability Act
DWQPA - Department of Water Quality Planning and Assessment
FS - Feasibility Study
OEPA - Ohio Environmental Protection Agency
USEPA - U.S. Environmental Protection Agency
-------
Table 4. State Action-Specific ARARs for OU 1
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph
Regulation Description
May pertain to any site where air
contaminant emissions occur either as
a preexisting condition of the site or as
a result of remedial activities. Should
be considered for virtually all sites.
ARAR

ARAR
Implementation of the substantive
provisions of state air reguirements as
ARARs is reguired by Section 121 (d) of
CERCLA.
Filling, grading, excavating, building, drilling, of mining on
lend where a hazardous waste or solid waste facility was
operated is prohibited without prior authorization from the
director of the OEPA.
Implementation of the substantive
provisions of state reguirements relating
to intrusive activities at former disposal
sites as ARAR4 is reguired by Section
121 (d) of CERCLA.
No hazardous waste facility shall emit any particulate
matter, dust, fumes, gas, mist, smoke, vapor, or odorous
substance that interferes with the comfortable enj oyment
of life or property or that is inj urious to public health.
Pertains to any site where hazardous
waste will be managed so that air
emissions may occur. Consider for
sites that will undergo movement of
earth or incineration.
Air emissions may be involved as part of
the treatment in several of the
alternatives. Alternatives involving air
emissions will be coordinated with
US EPA and OEPA to ensure emissions are
within acceptable limits.
A) Prohibits commingling low-level radioactive waste with
any type of solid, hazardous, or infectious waste.
B) No owner or operator of a solid, infectious, or
hazardous waste facility shall accept, any radioactive
waste for transfer, storage, treatment, or disposal.
Pertains to any site at which solid
waste has come to be located or will
be generated during a rememdial
action.
Solid wastes generated as part of the
remedy will be subj ect to this
reguirement.
Hazardous Waste
Facility Environmental
Impact/3734.05
(D) (6) (c)
A hazardous waste facility Installation end operation
permit shall not be approved unless the facility is proven
to represent the minimum adverse environmental impact
considering the state of available technology, the nature
and economics of various alternatives, and other pertinent
considerations.
Pertains to all sites where hazardous
wastes are located and/or where
hazardous wastes will be treated,
stored, or disposed of. May function
as siting criteria.
-------
Table 4. (page 2 of 8)
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph
Regulation Description

(D)(6)(d). A hazardous waste facility installation and
operation permit shall not be approved unless it proves
that the facility represents the minimum risk of all of the
following:
(i) Contamination of ground and surface waters.
(ii) Fires or explosions from treatment, storage, or
disposal methods.
(iii) Accident during transportation.
(iv) Impact on public health end safety.
(v) Soil contamination.
Pertains to all sites at which hazardous,us
waste has come to be located end/or
at which hazardous will be treated,
stored, or disposed of. May function
as siting criteria.
ARAR

ARAR
(ii) Any naturally occurring wetland.
(iii) Any flood hazard area.
(iv) Within any state park or national park or
recreation area.
Prohibits disposal of acute hazardous waste unless it:
(1) cannot be treated, recycled, or destroyed; (2) has
been reduced to its lowest level of toxicity; and (3) has
been completely encapsulated or protected to prevent
leaching.
Based on available information, only one
waste disposed of prior to construction of
the sanitary landfill, beryllium machining
wastes, may be determined to be an
acute hazardous waste. Currently, there
is some guestion whether such wastes
would have been considered off-
specification commercial chemical
products, identifiable as P015 listed acute
hazardous wastes. If such a listing is
appropriate, this
standard will be
regarded as ARAR for any alternatives
involving generation of listed beryllium
hazardous wastes.
-------
Table 4. (page 3 of 8)
Regulation Title or
Subject/Revised Code
Section and Pertinent
Paragraph
Establishes water guality criteria for pollutants that do not
have numerical or narrative criteria identified in
Tables 7-1 through 7-15 of this rule.
Pertains both to discharges to surface
waters as a result of remediation and
to any onsite surface waters affected
by site conditions.

Pertains both to discharges to surface
waters as a result of remedial action
and to any surface waters affected by
site conditions.
Alternatives involving direct discharge will
comply.
Pertinent if stream or stream segment
is onsite and is affected by site
conditions or if remedy includes direct
discharge. Used by DWQPA to
establish waste load allocations.
Water Use
Designations for Great
Miami River13746-1-21
Pertinent if stream or stream segments
is onsite and is affected by site
conditions or if remedy includes direct
discharge. Used by DWQPA to
establish waste load allocations.
Mandates that groundwater walls be:
A) Located and maintained to prevent contaminants from
entering the wall.
B) Located to be accessible for cleaning and
maintenance.
Pertains to all groundwater wells on
the site that either will be installed or
have been installed sam February
1975. Would pertain during the FS if
new wells are constructed for
Specifies minimum construction reguirements for new
groundwater wells with regard to els keg material, casing
depth, potable water, annular spaces, use of drive shoe,
openings to allow water entry, and contaminant entry.
Pertains to all groundwater wells on
the site that either will be installed or
have bean Installed since 15 February
1975. Would pertain during the FS if
new wells are constructed for
treatability studies.
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Table 4. (page 4 of 8)
Regulation Title
Subj ect/Revised Code
Section and Pertinent
Paragraph
Regulation Description
Pertains to all groundwater wells on
the site that either will be installed or
have been installed since 15 February
1975. Would pertain during the FS if
new wells are constructed for
treatability studies.
Will be applied for new well installation
part of any alternatives.
Surface Design of New
of GW Wells/
3745-9-07 A-F
Pertains to all groundwater wells on
the site that either will be installed or
have been installed since 15 February
1975. Would pertain during the FS if
new wells are constructed for
treatability studies.
Maintenance and
Operation of GW
Wells/
3745-9-09 A-C,D1,E-G
Pertains to all groundwater wells on
the site that either will be installed or
have been instifled since 15 February
1975. Would pertain during the FS if
new wefts are constructed for
treatability studies.

Pertains to all groundwater wells on
the site that either will be installed or
have been installed since 15 February
1975. Would pertain during the FS if
new wells are constructed for
treatability studies.
Will be applied for new well installation
part of any alternatives.
Abandonment of Test
Holes and GW Wells/
3745-9-10 A,B,C
Following completion of use, wells and te
completely filled with grout or similar material and shall be
maintained in compliance of all regulations.
Pertains to all groundwater wells on
the site that either will be installed or
have been installed since 15 February
1975.
Will be applied for new well installation as
part of any alternatives.
Provides that an air contaminant source is exempt from
permitting reguirements, provided it has the potential to
emit no more than 10 pounds per day of criteria
pollutants or 1 ton per year of hazardous air pollutants.
Will be applied to
the potential to emit criteria or hazardous
air pollutants.
-------
Table 4. (page 5 of 8)
Regulation Title or
Subject/Revised Code
Section and Pertinent
Paragraph
Emission Restrictions
for Fugitive Dust/
3745-17-08
Al ,A2,B,D
Defines air pollution nuisance as the emission or escape
into the air (from any source) of smoke, ashes, dust, dirt,
grime, acids, fumes, gases, vapors, odors, end
combination of the above that endanger health, safety,
or welfare of the public or cause personal inj ury or
property damage. Such nuisances are prohibited.
Pertains to any site that causes, or
may reasonably cause, air pollution
nuisances. Consider for sites that will
undergo excavation, demolition, cap
installation, methane production,
incineration, and waste fuel recovery.

Pertains to sites that may have fugitive
emissions (non-attack) of dust.
Consider for sites that will undergo
grading, loading operations,
demolition, clearing and grubbing, and
construction.
Air emissions may be involved as part of
the treatment in several of the
alternatives. Alternatives involving air
emissions will be coordinated with
US EPA end OEPA to ensure emissions are
within acceptable limits.

Air emissions may be involved as part of
the treatment in several of the
alternatives. Alternatives ismlying air
emissions will be coordinated with
USEPA and OEPA to ensure fugitive dust
emissions are within acceptable limits.
Pertain to any site that will emit
carbon oxides, ozone, or non-methane
hydrocarbons. Consider for sites that
will undergo water treatment,
incineration, and fuel burning (waste
fuel recovery).
Alternatives involving air emissions will
be coordinated with USEPA and OEPA to
ensure emissions are within acceptable
limits.
Specifies measurement methods to determine ambient air
guality for carbon monoxide, ozone, and non-methane
hydrocarbons.
Prohibits significant and avoidable deterioration of air
guality.
Pertains to any site that will emit
carbon monoxide, ozone, or non-
methane hydrocarbons. Consider for
sites where treatment systems will
result in air emissions.
Alternatives involving air antiasians IA
be coordinated with USEPA and OEPA to
ensure emissions are within acceptable
limits.
Alternatives involving air emissions will
be coordinated with USEPA end OEPA to
ensure emissions me within acceptable
-------
Table 4. (page 6 of 8)
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph
Regulation Description
Organic Materials
Emission Control;
Stationary Sources/
3745-21-07 A,B,G,I,J
Pertains to any site that is emitting or
will emit organic material. Consider for
sites that will undergo water
treatment, incineration, and fuel
burning (waste fuel recovery).

Pertains to any site that is emitting or
will emit VOCs. Consider for sites that
will undergo water treatment.
Alternatives involving air emissions will
be coordinated with USEPA and OEPA to
ensure organic materials emissions we
within acceptable limits.
Alternatives involving air emissions will
be coordinated with USEPA end OEPA to
ensure VOC emissions are within
acceptable limits.
Defines exemptions to solid waste regulations and
establishes limitations on temporary storage of putrescible
waste or any solid waste that causes e nuisance or health
hazard. Storage of putrescible waste beyond 7 days is
considered open dumping.
Pertains to any site where solid waste
will be managed. Consider especially
for old landfills where solid waste may
be excavated and/or consolidated.
Sanitary Landfill -
Ground Water
Monitoring/
3745-27-1 0 B-D
Establishes allowable methods of solid wests disposal:
sanitary landfill, incineration, composting. Prohibits
management by open burning and open dumping.
Groundwater monitoring program must be established for
all sanitary landfill facilities. The system must consist of
sufficient number of wells that are located as that
samples indicate both upgradient (background) and
downgradient water samples. The system must be
designed per the minimum reguirements specified in this
rule. The sampling and analysis procedures used must
comply with this rule.
Pertains to any site where solid wastes
will be managed. Prohibits
management by open burning and
open dumping.

Pertains to any new solid waste facility
and any expansions of existing solid
waste landfills offsite. Also may
pertain to existing areas of
contamination that are capped in-place
per the solid waste rules.
Will be applied to any alternative that
involves generation of solid wastes.
None of the alternatives involve open
burning or open dumping.
Disturbances Where
Hazardous or Solid
Waste Facility Was
Operated/
3745_27-i3 c
Prohibits any filling, grading, excavating, building, drilling,
or mining on land where a hazardous waste facility or
solid waste facility was operated without prior
authorization from the director of the USEPA. Special
terms to conduct such activities may be imposed by the
director to protect the public and the environment.
Pertains to say site where hazardous
or solid waste has been managed,
either intentionally or otherwise. Does
not pertain to areas that have had one-
time leaks or spills.
The RD/RA Work Plan will comply with
this reguirement.
-------
Table 4. (page 7 of 8)
Regulation Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph
Regulation Description
Post-Closure Care of
Sanitary Landfill
Facilities/
3745-27-14 A
Specifies the reguired post-closure care for solid waste
facilities. Includes continuing operation of leachate and
surface water management systems, maintenance of the
cap system, and groundwater monitoring.
Substantive reguirements pertain to
newly created solid waste landfills
ontsite, expansions of existing solid
waste landfills onsite, and existing
areas of contamination that are capped
per the solid waste rules.
Evaluation of existing closed sanitary
landfill conditions will be included in all
but the no-action alternative and
necessary modifications/repairs win be
made .
Water/Air Permit
Criteria for Decision by
the Director/
3745-31-05
A permit to install or plans must demonstrate best
available technology end shall not interfere with or
prevent the attaintment or maintenance of applicable
ambient air guality standards.
Alternatives involving onsite water
discharge will comply. Air emissions may
be involved as part of the treatment in
several of the alternatives. Alternatives
involving air emissions will be coordinated
with USEPA and OEPA to ensure
emissions are within acceptable limits.

Any materials generated during
construction or implementation of
remedial actions will be evaluated to
determine if it is identifiable as a
hazardous waste, or if it is sufficiently
similar to a hazardous waste that
hazardous waste management standards
should be applied.
Pertains to any site that has
contaminated onsite surface water or
groundwater of will have a discharge
to onsite surface water or
groundwater.
Implementation of the substantive
provisions of state water reguirements as
ARARs is reguired by Section 121 (d) of
CERCLA.
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Table 4. (page 8 of 8)
Regulations Title or
Subj ect/Revised Code
Section and Pertinent
Paragraph

Water Pollution Control
Reguirements-
Duty to
Comply/6111.07 A,C
Regulation Description
Pertains to any site that has
contaminated groundwater or surface
water or wilt have discharge to
onsite surface or groundwater.
ARAR

ARAR
Implementation of the substantive
provisions of state water reguirements as
ARARs is reguired by Section
CERCLA.
National Pollution Discharge Elimination System:
Wastewater Discharges Resulting from Clean-up of
Response Action Sites Contaminated with VOCs.
ARAR - applicable or relevant and appropriate reguirement
CERCLA - Comprehensive Environmental Response. Compensation, and Liability Act
DWQPA - Department of Water Quality Planning and Assessment
FS - feasibility study
• g/L - micrograms per liter
OEPA - Ohio Environmental Protection Agency
ORC - Ohio Revised Code
TEC - to 0 be considered
USEPA - U.S. Environmental Protection Agency
VOC - volatile organic compound
Establishes guidelines for the disposal
of wastewaters, of both short-and
long-term discharge categories,
resulting from cleanup response action
sites contaminated with VOCs, and the
operating interface between the
involved OEPA divisions. For
discharges to surface water or storm
sewers, the Best Available Treatment
Technology/Best Available
Demonstrated Control Technology
(BATT/BADCT) must be applied to
achieve 5/*g/L or less for each VOC
parameter listed.
TEC,
Not ARAR
This policy addresses short-term
discharges (pump tests end treatability
tests) and long-term discharges (interim
and remedial actions). This policy
provides guidelines for achievement of
less that 5 •g/L for specific VOC
parameters by utilizing BATT/BADCT for
those compounds. BATT/BADCT
consists of air stripping, carbon columns
or both or eguivalent to achieve the 5
•g/L or lees.
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Table 5. Federal Action-Specific ARARs for OU 1
Best Available Technology:
Use of best available technology
economically achievable is reguired
to control toxic and nonconventional
pollutants. Use of best conventional
pollutant control technology is
reguired to control conventional
pollutants. Technology-based
limitations may be determined on a
case-by-case basis.
Alternatives involving
discharges to surface waters
will comply.
Water Quality Standards:
Must comply with applicable
federally approved state water
guality standards. Whole standards
may be in addition to or more
stringent than other federal standards
under the CWA.
40 CFR 122.44 and state regulation;
approved under 40 CFR 131
Alternatives involving
discharges to surface waters
will comply.
Discharge limitation must be
established at more stringent levels
than technology-based standards for
toxic pollutants.

Best Management Practices:
Develop and implement a best
management practices program to
prevent the release of toxic
constituents to surface waters.
Establish specific procedures
for the control of toxic and
hazardous pollutant spills.

Include prediction of
direction, rate of flow, and total
guantity of toxic pollutants
where experience indicates a
reasonable potential for
eguipment failure.
Ensure proper management of
solid and hazardous waste in
accordance with regulations
promulgated under RCRA.
-------
Table 5. (page 2 of 3)

Requirement

Management Requirements:
Discharge must be monitored to
ensure compliance. Discharge will
monitor:
Frequency of discharge and
other measurements as
appropriate.

Approved test methods for waste
constituent to be monitored must be
followed. Detailed requirements for
analytical procedures and quality
controls are provided.
Movement of excavated materials to
new location and placement in or on
land will trigger and disposal
restrictions for the excavated waste
or closure requirements for the unit
which the waste is being placed.
The area from which materials are
excavated may require cleanup to
levels established by closure
requirements.

Requires storm water discharges to
be permitted under the federal (or
state) NPDES program. Different
requirements are applicable for
different classes and types of
discharges.
Materials containing RCRA
hazardous wastes subj ect to
land disposal restrictions a
placed in another unit.
RCRA hazardous waste
placed at site after the
effective date of the
requirements.
Alternatives involving onsite
discharge to sewer systems
will comply.
-------
Table 5. (page 3 of 3)

Requirement
All surface water discharges must be
in compliance with promulgated Ohio
Stream Discharge Standards
ARAR - applicable or relevant and appropriate requirement
CWA - Clean Water Act
NPDES - National Pollutant Discharge Elimination System
RCRA - Resource Conservation and Recovery Act
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ATTACHMENT C

COMMUNITY RELATIONS
ACTIVITIES FOR OU 1, AREA B

MOUND

Operable Unit I/Area B

Environmental
Restoration
Program Ken Hacker, Manager
September 1994
Addresses possible volatile
organic chemical contamina-
tion of the portion of the Buried
Valley Aguifer which underlies
the southwest corner of the
original Mound Plant.

OU1 covers four acres and
includes an historic landfill, the
site sanitary landfill and an
overflow pond.

The main concerns at this site
are volatile organic compounds
that may be migrating into the
groundwater. It is believed that
such contamination originates
from the historic landfill site that
was formerly used for open
burning and waste disposal.
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PURPOSE

! Determine possible contamination of the Buried Valley Aquifer from:
historic landfill containing:
Mound Plant used this area as burn area to dispose of solid and liquid wastes
Empty crushed thorium drums burial in this area in 1955 and 1956
sanitary landfill
Built in 1977 with materials excavated durinq construction of overflow pond
Constructed over site of encapsulated waste relocated from historic landfill
overflow pond (stormwater retention pond)
! Gather enouqh information from this area to determine if a cleanup is necessary and, if so, how best to proceed with the remedial action.

PRIMARY CONTAMINANTS OF CONCERN

Volatile orqanic compounds (VOCs)

WORK SCOPE

Determine by use of soil samplinq, soil qas surveys and hydroqeoloqy surveys, whether contaminants found in Area B are beinq
carded off-site throuqh qroundwater.

PROGRESS TO DATE

Subsurface soil samplinq and soil qas samplinq to identify contaminants in the soil, Auqust-December, 1992
Installation of 27 monitorinq wells and piezometers. October-March, 1993
Aquifer pump test conducted usinq newly-installed and existinq Test wells to characterize qroundwater flow in the immediate
vicinity of Area B. May-June, 1993
Fieldwork for RI/FS complete after aquifer pump test

DOCUMENTS IN PUBLIC REPOSITORY SCHEDULE FOR REMAINDER OF 1994
History of Area B (February, 1991) FSR/Proposed Plan to be complete in calendar year 1994
Proposal for Additional Work (September, 1992) Beqin work on Record of Decision (ROD)
Remedial Investiqation Report (RI) (July, 1994)

FUTURE SCHEDULE MILESTONES (Fully Funded)
FY95 ! Prepare Feasibility Study/prepare Proposed Plan FY96: ! Beqin work on Remedial Desiqn
! Complete FSR/PP
! Complete Record of Decision (ROD)
! Beqin work on RD/RA Work Plan

For more information, contact: EG&G Mound Community Relations at (513) 865-4140
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MOUND

Environmental
Restoration
Program

DOE Issues a Proposed Plan
Operable Unit I/Area B

Ken Hacker, Manager
FACT SHEET
November 1994
Operable Unit 1 (OU1). Area B. of the Mound Plant occupies
approximately four acres the southwestern portion of the
plant site. This area of the plant is located over the eastern
side of the Buried Valley Aquifer (BVA) which has been desig-
nated as a sole source aguifer by the U.S. EPA. From 1948 to
1977, Mound used Area B, formerly a gravel excavation area,
for disposing of general trash and nonradioactive liguid
waste. Solid wastes, mostly paper, office and kitchen garbage,
were typically placed in a burn cage at Area B and Ignited to
reduce their volume; liguid wastes, including solvents, oils,
and chemicals were typically dumped or burned. Much of this
waste was later relocated and encapsulated in a new site san-
itary landfill constructed in 1977. At that time, an overflow
pond for stormwater runoff was also constructed, partially
covering the historic landfill site. After 1977, waste was no
longer disposed of in Area B. Now, testing has revealed that
the volatile organic compounds (VOCs) from the Area B
historic landfill have migrated through softs and groundwater
into a portion of the Buried Valley aguifer beneath the land-
fill. In addition, tritium was detected in past water samples
taken from wells in Area B, although the concentration was
below the drinking water maximum contaminant level.
Mound studies have shown the source of tritium in the BVA
to be contaminated sediments in the Miami-Erie Canal. Thus,
the environmental concerns in Area B center on VOCs in the
contaminated soils and waste materials contained within the
area and on the groundwater system directly beneath and ad-
jacent to the Mound site. The contaminated groundwater in
OU1 is a concern at the site because of the potential for

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directly ingesting contaminants through drinking water and
the possible offsite migration of the VOC-contaminated
portion of the aguifer.

Remedial Investigation and Feasibility Study Completed

To address VOC soil and water contamination concerns in Area B, a baseline risk assessment was done,
followed by a remedial investigation and feasibility study (RI/FS). The baseline risk assessment was
structure to address future public health risks, assuming no remedial actions were undo-taken. The study
focused on exposure of hypothetical future residents and site workers to soft and groundwater
contamination through inhalation, incidental ingestion, external exposure to radiation emitted from
radionuclides in the soil, and skin contact with the soft. Ingestion and inhalation contribute almost all of
the risk, and groundwater is the most important exposure medium. Because groundwater would contribute
most of the carcinogenic and noncarcinogenic risks to future residents or workers, it is the focus of the
remedial efforts to reduce the overall risk.

The (RI/FS) aimed seven alternatives for protecting human health and the environment while achieving
the remedial goals. All seven of the alternatives include several common components. Each alternative
includes surface controls, such as grading and lining existing ditches to manage runon and runoff;
institutional controls, such as fencing and access restrictions to limit access to the site; and long-term
groundwater monitoring. Each of the alternatives is discussed in the "Operable Unit 1 Proposed Plan." This
and other documents on OU1 are available to the public in the CERCLA Reading Room at the Miamisburg
Senior Adult Center.
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WHAT ARE VOLATILE
ORGANIC COMPOUNDS?

Readers of Superfund Update may
recall the feature article on volatile
organic compounds (VOCs) in the
January/February 1994 issue. VOCs
compromise a wide array of everyday
chemicals. From gasoline, anti-
freeze; and pesticide sprays, to
paints, glues, and waxes-VOCs are
found in household and industrial
products all around us. Though
indispensable to modern life, VOCs
can pose some significant hazards.
And because they are so common,
they often turn up as contaminants in
the environment. VOCs evaporate
readily and so can quickly fill an en-
closed space with noxious and dang-
erous fumes. They do not dissolve
easily in water and so pose water
contamination problems when they
find their way to lakes, rivers, and
streams. Long-term exposure to low
concentrations can affect the liver,
kidneys, heart, blood, reproductive
organs, and nervous system. Some
VOCs, such as benzene, are known
to cause cancer. VOCs are released
into the environment trough evapor-
ation, accidental spills, leaks, or
inadequate disposal methods. Drink -
ing VOC-contaminated water, inhal
ing evaporated VOCs, or absorbing
VOCs through skin contact are the
main exposure routes for humans.

The CERCLA statute currently con-
siders 33 VOCs to be hazardous
substances that may pose a poten-
tial hazard to human health or the
environment if improperly treated,
The Preferred Alternative

The preferred alternative for cleaning up the VOC-contaminated soils
and groundwater at OU1 combines collection, treatment, and disposal.
Because this alternative reduces the toxicity and volume of contami-
nated water and controls its migration, it is protective of both the
Mound Plant well field and the Buried Valley aquifer. The action would
effectively capture contaminated groundwater beneath the Operable
Unit 1 site for treatment before it migrates offsite. Treatment methods
for VOCs the could include ultraviolet (UV) oxidation treatment, cas-
cade aeration, or conventional air stripping. A final selection of treat
ment technologies will be done following the public comment period
during the remedial design phase. Based on current information, the
DOE, in consultation with the U.S. and Ohio Environmental Protection
Agencies, will select a final remedy for the site after the public comment
period has ended and the information submitted during this time will
have been reviewed and considered.

Soil Sampling at Operable Unit 1
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stored, transported, or disposed. At
Mound, VOCs have been used in the
past to clean or degrease metal
parts, tools, molds, and other equip-
ment. Among those in common use
were acetone, benzene, chloroform,
freon, and toluene.

If VOCs are discovered in soil or
water in concentrations above fed-
eral or state standards, environ-
mental laws such as CERCLA re-
quire cleanup action. There are a
number of remedies for handling
VOC contamination in soil and
groundwater. Contaminated soils
can be covered with caps to elim-
inate potential exposure routes;
excavated soil may be transported to
a landfill or incinerator for disposal;
soils may be treated in place by soil
vapor extraction; VOC-contaminated
groundwater may be pumped out for
treatment and discharge.
PUBLIC COMMENT PERIOD

Beginning November 15, 1994, and continuing through December 30,
1994, the Department of Energy is accepting public comments on the
Proposed Plan for Operable Unit 1.

The public is invited, and encouraged to review the Proposed Plan,
the CERCLA Public Reading Room, Miamisburg Senior Adult Center,
305 Central Avenue, Miamisburg, Ohio.

Comments can be sent in writing to:
Jolene Walker
EG&G Mound Community Relations
P.O. Box 3000, OSE-245
Miamisburg, Ohio 4543-3000

The public can also give comments at a public hearing for OU1 on
Thursday, December 8, 1994, at 7:00 p.m. in the Miamisburg Civic
Center Council Chambers, 10 N. First Street, Miamisburg, Ohio.
at
For more information, contact: EG&G Mound Community Relations at (513) 865-4140.
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MOUND

Environment
Restoration
Program
Operable Unit I/Area B
Hacker, Manager
FACT SHEET #2
December 1994
Proposed Plan Supplementary Information
Based on official Public Comments received
at the December 8, 1994, Public Meeting for
Operable Unit 1 Proposed Plan, a guestion
was raised concerning Table 1 on page 9 of
the Proposed Plan. The guestion concerned
the apparent similarity of Alternatives 3 and
4 with the exception of maximum total cost.
The attachment clarifies Table 1 by sum-
marizing the reduction of taxicity, mobility or
volume of contaminants that each Alter-
native addre s s e s.

Alternative 3 meets the mobility and volume
reduction statutory preference for selecting
remedial actions (page 4-10 of the Operable
Unit 1 Feasibility Study). It does not address
toxicity reduction, which is also a statutory
preference for selecting remedial actions.
Therefore, DOE in consultation with U.S.
EPA and Ohio EPA, has determined that
Alternative 4, which includes treatment to
reduce toxicity, is preferable. The reduction
of toxicity, mobility or volume for Alternative
4 is explained on page 4-14 of the Operable
Unit 1 Feasibility Study.

Guidance from the Ohio Environmental Pro-
tection Agency states that waste water
discharges resulting from cleanup of res-
ponse action sites contaminated with volatile
treated with best available technology for
toxicity reduction. The State of Ohio believes
that Alternative 3 does not meet those re-
reguirements.

Table 1 identifies the 7 primary evaluation
criteria reguired by 40 CFR 300. This law
also gives 2 additional "modifying criteria"
which are (1) state acceptance and (2) com-
munity acceptance. Based on the States
position on Alternative 3, Alternative 4 was
chosen as the preferred alternative. The final
decision will also include evaluation of com-
muntty acceptance based on public corn-
merits received.

Alternatives 3 through g comply with ARARs
and achieve adeguate protection of human
health and the environment. These alterna-
tives are correctly identified in Table 1 of the
Proposed Plan, however, the text on page 8
of the Proposed Plan incorrectly stated that
all alternatives met ARARs.

Please keep in mind that the Proposed Plan
only identifies the preferred option for clean-
up of contamination of Operable Unit 1. A
more detailed description of the alternatives
is provided in the Operable Unit 1 Feasibility
Study.
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organic compounds (VOCs) need to be

Public Comment Period

The public comment period for the Proposed Plan has been extended to January 31, 1995. The
public is invited, and encouraged, to review the Proposed Plan. Feasibility Study, and
Supplementary Information, at the DOE Public Reading Room, Miamisburg Senior Adult
Center, 305 Central Ave., Miamisburg, Ohio. For guestions or comments, contact EG&G
Community Relations at (513) 865-4140.
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Table 1. Summary of Remedial Action Alternative Comparison

irnative
1
2
3
4
5
6
7
8
9

Short Title
No Action
Institutional
Collect/
Disposal
Collect/Treat/
Disposal
Collect/Treat/
Disposal/Cap
Contain/Collect/
Treat /Disposal/
Contain/Collect/
Treat /Disposal/
Cap
In-situ GW
Treatment
In-situ GW
Treatment /Cap

Complies
With
ARARs
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes

Short-term
Effectiveness
No
No
Adequatea
Adequatea
Adequateb
Adequateb
Adequateb
Adequateb
Adequateb
Protects
Human
Health and
Lonq-term the
Effectiveness Environment
No No
No No
Yes Adequate
Yes Adequate
Yes Adequate
Yes Adequate
Yes Adequate
Yes Adequate
Yes Adequate

Reduces
TMV
No
No
Yes
MV
Yes
TMV
Yes
TMV
Yes
TMV
Yes
TMV
Yes
TMV
Yes
TMV

Implementability
Easy
Easy
Less Difficult
Less Difficult
Less Difficult
Moderately
Difficult
Moderately
Difficult
More Difficult
More Difficult

Total Cost
$ 0
$ 3,980,000
$262,000°
$ 1,740,000
$ 2,390,000
$ 2,650,000
$ 3,300,000
$ 1,980,000
$ 2,630,000
aQuicker implementation when compared to other alternatives.
bLonqer construction time when compared to other alternatives.
"This Total Cost is in addition to the Total Cost shown for Alternative 2 (common cost)
ARARs - Applicable or relevant and appropriate requirements.
TMV - Toxicity, Mobility, or Volume, appropriate, this
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