United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R04-91/097
September 1991
EPA Super!und
Record of Decision
Maxey Flats Nuclear
Disposal, KY
-------
50272-101
REPORT DOCUMENTATION 1'. REPORT NO. I ~ 3. ReclpIent'a Acc:e88lon No.
PAGE EPA/ROD/R04-91/097
4. Tille and Sub1IIIe 5. Repor1 Date
SUPERFUND RECORD OF DECISION 09/30/91
Maxey Flats Nuclear Disposal, KY
6.
First Remedial Action - Final
7. Author(a) 8. F8rfonning Organia1lon RefIt. No.
8. F8rfonning Orgainizlltion Name and Addreaa 10. Projec:1lT..klWork UnI1 No.
11. ComnC1(C) or Grant(G) No.
(C)
(G)
1~ Sponaorlng Organiz81ion Name and Addreaa 13. Type of Report & Period Covered
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. Supplementary Notea
16. Abetrac:1 (UR'III: 200 words)
The 280-acre Maxey Flats Nuclear Disposal site is an inactive low-level radioactive
waste disposal facility in Fleming County, Kentucky. Land use in the area is
predominantly agricultural and residential, with mixed woodlands surrounding the
site. The estimated 663 people who reside within 2.5 miles of the site use the
public water supply for drinking purposes. From 1962 to 1977, Nuclear Engineering
Company, Inc. (NECO), operated a solid by-product, source, and special nuclear
material disposal facility under a license with the State. During this time, NECO
disposed of approximately 4,750,000 cubic feet of low-level radioactive waste in an
approximately 45-acre area, designated as the "Restricted Area". The majority of the
waste was disposed of in unlined trenches, but concrete capped "hot wells" consisting
of coated steel pipe, tile, or concrete also were used for disposal of small-volume
wastes with high-specific activity. The wastes were deposited in 52 disposal
trenches within 27 acres of the Restricted Area in both solid and sOlidified-liquid
form and were both containerized and deposited loosely. Several State investigations
in the 1970' s revealed that leachate contaminated with tritium and other radioactive
substances was migrating from the disposal trenches to unrestricted areas. In 1977,
(See Attached Page)
17. Documenl Analysia L Desc:riplors
Record of Decision - Maxey Flats Nuclear Disposal, KY
First Remedial Action - Final
Contaminated Media: soil, debris
Key Contaminants: VOCs (benzene, TCE, toluene), metals (arsenic, lead), radioactive
materials
b. Identifiers/Open-Ended Terms
c. COSA T1 Field/Group
18. Avllilability Statement 18. Security Cia.. (This Report) 21. No. 01 Pagea
None 197
I 20. Security Cia.. (This Page) 22. PrIce
None
ANSl-Z39.18 See Inlllrucr;onll on Reve"", . )
(See
(Formerty NTlS-35)
Department 01 Convnerc:e
-------
EPA/ROD/R04-91/097
Maxey Flats Nuclear Disposal, KY
First Remedial Action - Final
Abstract (Continued)
the State ordered NECO to cease the receipt and burial of radioactive waste. From 1973
to 1986, an evaporator was operated onsite as a means of managing the large volume of
water infiltrating the disposal trenches as well as wastewater generated by onsite
activities. The evaporator processed more than 6,000,000 gallons of liquids, leaving
behind evaporatory concentrates that were stored in onsite above-ground tanks, and
eventually disposed of in an onsite trench. In 1979, the State initiated stabilization
and maintenance activities including installing a temporary PVC cover over the disposal
trenches to minimize rainfall infiltration. In 1988, EPA conducted a two-phase removal
action to handle the threat posed by 11 onsite 20,000-gallon tanks of questionable
structural integrity located in a tank farm building. Phase I consisted of installing
a heater in the tank farm building to prevent the freezing and rupturing of tank valves
and fittings. Phase II consisted of solidifying approximately 286,000 gallons of
radioactive liquids stored in the 11 tanks and water on the floor of the tank farm
building. The solidified blocks will be disposed of onsite in a newly constructed
trench. This Record of Decision (ROD) addresses final remediation of soil, debris, and
associated leachate. The primary contaminants of concern affecting the soil and debris
are VOCs including benzene, TCE, and toluene; metals including arsenic and lead; and
radioactive materials.
The selected remedial action for this site includes extracting, solidifying, and
disposing onsite of approximately 3,000,000 gallons of trench leachate; demolishing and
disposing of site structures onsite; excavating additional disposal trenches for
disposal of site debris and solidified leachate; installing an approximately 50-acre
initial cap consisting of a clay and synthetic liner after disposal of solidified
leachate and debris in the trenches; maintaining and periodically replacing the initial
cap synthetic liner as needed every 20 to 25 years; re-contouring the capped disposal
area as needed to enhance the management of surface water run-on and runoff;
temporarily storing any additional wastes generated after constructing the initial cap
onsite, followed by solidification and onsite disposal of those wastes in a newly
constructed disposal trench; installing a ground water flow barrier, if necessary;
installing an infiltration monitoring system to continuously verify remedy performance
and detect the accumulation of leachate in disposal trenches; installing a final
engineered multi-layer cap once natural subsidence of the trenches has nearly ceased,
which could take 100 years; installing permanent surface water control features;
monitoring soil, sediment, surface water, ground water, leachate, air, selected
environmental indicators, and rates of subsidence; procuring a buffer zone adjacent to
the site to prevent deforestation or erosion of the hill slopes, which could affect the
integrity of the selected remedy, and to provide an area for monitoring; and
implementing institutional controls including land use restrictions. The estimated
present worth cost for this remedial action is $33,500,000, which includes a present
worth O&M cost of $10,097,549.
PERFORMANCE STANDARDS OR GOALS: Implementation of this remedy will result in the
reduction of risk from 10-1 to 10-4.
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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
RECORD OF DECISION
REMEDIAL ALTERNATIVE SELECTION
MAXEY FLATS DISPOSAL SITE
FLEMING COUNTY, KENTUCKY
. PREPARED BY:
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION IV
ATLANTA, GEORGIA
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DECLARATION STATEMENT
RECORD OF DECISION
MAXEY FLATS DISPOSAL SITE
FLEMING COUNTY, KENTUCKY
SITE NAME AND LOCATION
Maxey Flats Disposal Site, Fleming County, Kentucky
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for
the Maxey Flats Disposal Site, developed in accordance with the
Comprehensive Environmental Response, Compensation and Liability
Act (CERCLA) of 1980, as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), and to the extent
practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). The remedy selection is based upon the
Administrative Record for the Maxey Flats Disposal Site.
The Commonwealth of Kentucky has concurred in the selected
remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response action
selected in this Record of Decision, may present an imminent and
substantial endangerment to public health, welfare, or the
environment.
DESCRIPTION OF REMEDY
This final remedy substantially controls and reduces site risks
to an acceptable level through treatment, engineering and
institutional controls, and containment. The major components
of the selected remedy include:
.
Excavation of additional disposal trenches for disposal of
site debris and solidified leachate
.
Demolition and on-site disposal of site structures
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Declaration - Page 2
.
Extraction, solidifica~ion and on-site disposal of
approximately three million gallons of trench leachate
Installation of an initial cap consisting of clay
and a synthetic liner
.
.
Maintenance and periodic replacement of initial cap
synthetic liner
.
Re-contouring of capped disposal area to enhance
management of surface water runon and runoff
Improvements to existing site drainage features to enhance
management of surface water runoff
.
.
Installation of a ground water flow barrier, if necessary
Installation of an infiltration monitoring system to
continuously verify remedy performance and detect the
accumulation of leachate in disposal trenches
.
.
Monitoring of ground water, surface water, air, selected
environmental indicators, and rates of subsidence
.
Procurement of a buffer zone adjacent to the existing site
property boundary, estimated to range from 200 to 400
acres, for the purposes of preventing deforestation of the
hillslopes or other activities which would accelerate
hillslope erosion and affect the integrity of the selected
remedy, and to provide for frequent and unrestricted access
to areas adjacent to the site for the purpose of monitoring
.
Five year reviews to evaluate the protectiveness of the
remedy and to ensure the selected remedy is achieving the
necessary remedial action objectives
Institutional controls to restrict use of the Maxey Flats
Disposal Site and to ensure monitoring and maintenance
in perpetuity.
The estimated cost of the selected remedy is $ 33,500,000.
.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, attains Federal and State requirements that are
applicable or relevant and appropriate to the remedial action,
or obtains a waiver of specified requirements, and is cost
-------
Declaration - Page 3
effective. This remedy utilizes permanent solutions and
alternative treatment technologies to the maximum extent
practicable for the Maxey Flats Disposal Site. Because
treatment of the principle threats of the site wa.s not found to
be practicable; however, this remedy does not satisfy the
statutory preference for treatment as a principle element of the
remedy.
Because this remedy will result in hazardous substances
remaining on-site above health-based levels, a review will be
conducted within five years after commencement of remedial
action, and every five years thereafter, to ensure that the
remedy continues to provide adequate protection of human health
and the environment.
~th~~+\
Greer C. Tidwell /
Regional Administrator
SŁP 3 0 1991
Date
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SECTION
TABLE OF CONTENTS
1.0
DECLARATION
2.0
3.0
4.0
5.0
6.0
SITE
1.1
1.2
1.3
1.4
1.5
1.6
LOCATION AND DESCRIPTION ....................
Location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Demographics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Topography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Land Use....................................
Natural Resources...........................
1.5.1 Surface Water ........................
1.5.2 Geology and Ground Water .............
1 . 5 . 3 Biota. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Climate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SITE HISTORY AND ENFORCEMENT ACTIVITIES ..........
HIGHLIGHTS OF COMMUNITY PARTICIPATION ............
SCOPE AND ROLE OF RESPONSE ACTION ................
SUMMARY OF SITE CHARACTERISTICS ..................
5.1 Nature and Extent of Contamination ..........
5.1.1 Trench Characteristics ...............
5.1.2 Geology and Ground Water .............
5.1.3 Soils... .. . ..... ... . ...... .. . . ... . . . .
5.1.4 Surface Water and Sediments ..........
5 . 1 . 5 Air... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SUMMARY OF SITE RISKS............................
6.1 Off-Site Exposure Scenario ..................
6.1.1 Well Water Pathway...................
6.1.2 Surface Water Pathway................
6.1.3 Erosion Pathway......................
6.1.4 Sediment Pathway.....................
6.1.5 Deer Pathway.........................
6.1.6 Evapotranspiration Pathway...........
6.1.7 Trench Sump Pathway..................
6.1.8 Conclusions of the Off-Site
Exposure Scenario Analysis ...........
i
PAGE
1
1
1
5
5
6
6
9
9
10
11
16
19
20
20
22
28
33
48
54
57
59
59
62
62
64
64
64
66
66
-------
SECTION
7.0
8.0
9.0
TABLE OF CONTENTS (Continued)
PAGE
On-Site Exposure Scenarios ..................
6.2.1 Intruder-Trespasser Scenario .........
6.2.2 Intruder-Discovery Scenario ..........
6.2.3 Intruder-Construction Scenario .......
6.2.4 Intruder-Agriculture Scenario ........
6.2.5 Conclusions of the On-Site
Exposure Scenarios ...................
Risk Assessment Uncertainties ...............
6.2
6.3
67
67
67
67
69
69
73
77
77
78
78
79
79
81
83
84
DESCRIPTION OF ALTERNATIVES ......................
7.1 Remedial Action Objectives ..................
7 .2 Al ternati yes ................................
7.2.1
7.2.2
7.2.3
7.2.4
7.2.5
7.2.6
7.2.7
7.2.8
7.2.9
7.2.10
Stabilization Technologies ...........
Flow Barriers........................
7.2.2.1 vertical Flow Barriers ......
7.2.2.2 Horizontal Flow Barriers ....
Baseline Features ....................
Alternative 1 - No Action ............
Alternative 4.- Dynamic Compaction/
Structural Cap/Hor. Flow Barrier .... 84
Alternative 5 - Natural Stabilization/
Eng. Soil Cap/Hor. Flow Barrier ...... 85
Alternative 8 - Natural Subsidence/
Eng. Soil Cap/Hor. Flow Barrier ...... 87
Alternative 10 - Dynamic Compaction/
Eng. Soil Cap/Hor. Flow Barrier ...... 88
Alternative 11 - Trench Grouting/
Eng. Soil Cap/Hor. Flow Barrier ...... 89
Alternative 17 - Dynamic Compaction/
Eng. Soil Cap/Hor. Flow Barrier ...... 90
APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS (ARARS) ............................. 94
8.1 Action-Specific ARARs ....................... 94
8.2 Contaminant-Specific ARARs .................. 104
8.3 ARA,Rs Waiver................................ 108
SUMMARY OF THE COMPARATIVE ANALYSIS OF
ALTERNATIVES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 111
9.1 Evaluation Criteria ......................... 111
9.2 Comparative Analysis ........................ 112
9.3 Conclusions of the Comparative Analysis
SUIDDla'ry ..................................... 121
ii
-------
TABLE OF CONTENTS {Continued}
SECTION
PAGE
10.0
THE SELECTED REMEDY.............................. 122
10.1 Initial Closure Period ..................... 123
10.2 Interim Maintenance Period ................. 132
10.3 Final Closure Period ....................... 135
10.4 Custodial Maintenance Period ............... 141
11.0
STATUTORY DETERMINATIONS ......................... 142
11.1 Protection of Human Health and Environment. 142
11.2 Compliance with ARARs ...................... 143
11.3 Cost-Effectiveness ......~.................. 143
11.4 Utilization of Permanent Solutions and
Alternative Treatment Technologies or Resource
Recovery Technologies to the Maximum Extent
practicable and Statutory Preference for
Treatment as a Principle Element ................. 143
APPENDIX A
APPENDIX B
APPENDIX C
APPENDIX D
RESPONSIVENESS SUMMARY
NUMERIC CRITERIA FOR ARARS
PUBLIC MEETING TRANSCRIPT
SUPERFUND FACT SHEET PROPOSED PLAN -
MAXEY FLATS DISPOSAL SITE
ADMINISTRATIVE RECORD FILE INDEX
APPENDIX E
ill
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SECTION
1.1
1.1
1.1
1.4
5.1.1
5.1.2
5.1.2
5.1.3
5.1.3
5.1.3
5.1.4
6.1
6.2
6.2
8.2
8.2
9.2
10.1
10.1
10.2
10.2
10.3
10.3
10.3
FIGURE
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
LIST OF FIGURES
TITLE
1
2
3
4
Maxey Flats Disposal Site Location Map ...
Maxey Flats Disposal Site Vicinity Map ...
Location of Trenches, Trench Sumps and
Buildings in Restricted Area .............
Public Water Supply System ...............
Trench Sump Sampling Locations ...........
Geologic Cross Section ...................
Location of Monitoring Wells Sampled
for Ground Water .........................
Hand Auger Soil Sample Points and
Transect Locations .......................
Isopleths of Tritium Concentrations in
Moisture From Hand Auger Soil Samples ....
Location of Background and Food Crop
Study Area Soil Samples ..................
Location of Surfac~ Water and Sediment
Sampling Stations........................
5
6
7
8
9
Well Water Pathway Analysis ..............
Decay of Radionuclide Indicators .........
Decay of Radionuclide Indicators .........
PAGE
2
3
4
8
24
30
31
40
41
47
49
63
74
75
MFDS Area of Contamination ............... 103
Outline of Alluvial Deposits Where
Drinking Water Standards Will Be Applied
As Relevant and Appropriate .............. 106
Alternative 5 Subsidence Period Present
Worth Sensitivity Curves ................. 118
Construction Planning Drawinq ............ 126
Alternative 5 - Natural Stabilization .... 127
Vibrating Wire Piezometer ................ 129
MFDS Proposed Buffer Zone ................ 131
Ground Water Cutoff Wall and Collection
Wells For 40 Series Trenches ............. 136
Lateral Drain ..........................',' 137
Horizontal Flow Barrier .................. 138
iv
-------
SECTION
1.4
5.0
5.1.1
5.1.1
5.1.1
5.1.1
5.1.1
5.1.2
5.1.2
5.1.2
5.1.2
5.1.3
5.1.3
5.1.3
5.1.3
5.1.3
5.1.4
5.1.4
5.1.4
5.1.4
5.1.4
5.1.4
TABLE
9
10
11
12
13
14
15
16
17
18
19
20
21
22
LIST OF TABLES
TITLE
1
Acreage Tabulation For The Area Within
2.5 Miles of the MFDS ..................
2
3
4
5
6
RI Sampling and Analysis Program Summary
Trench Dimensions and Volumes ..........
Radionuclides in Trench Leachate .......
Results of Organic Chemical Analyses
for Trench Leachate ....................
Results of Inorganic Chemical Analyses
for Trench Leachate ....................
Results of RCRA Analyses for Trench
Leachate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
8
Radionuclide Concentrations in Ground
Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Organic Chemical Concentrations in
Ground Water....... . . . . . . . . . . . . . . . . . . . .
Inorganic Chemical Concentrations in
Ground Water...........................
Results of RCRA Analyses for Ground Water
Concentration Ranges of Radionuclides
in Soil................................
Concentration Ranges of Organic Chemicals
in Soil.................................
Concentration Ranges of Inorganic
Chemicals in Soil......................
Results of RCRA Analyses for Band Auger
Soil Samples (Round 2) .................
Results of RCRA Analyses for Soil Water
Concentration Ranges of Radionuclides
'in Surface Water .......................
Concentration Ranges of Organic
Chemicals in Surface Water .............
Concentration Ranges of Inorganic
Chemicals in Surface Water .............
Concentration Ranges of Radionuclides
in Stream Sediments ....................
Concentration Ranges of Organic Chemicals
in Stream Sediment .....................
Concentration Ranges of Inorganic
Chemicals in Stream Sediment ...........
v
PAGE
7
21
23
25
26
27
29
34
35
36,37
38
42
43
44
45
46
50
51
52
53
55
56
-------
SECTION
TABLE
6.0 23
6.1 24
6.1 25
6.2 26
6.2 27
7.2 28
7.2 29
8.0 30
8.0 31
9.2 32
10.3 33
LIST OF TABLES (Continued)
TITLE
Indicator Contaminants .................
Off-Site Pathways ......................
Erosion Pathways .......................
On-Site (Intruder) Pathways ............
Effective Dose Equivalents (mrem/hour)
for Transient Intruder .................
Summary of Alternatives that Underwent
a Detailed Analysis ....................
Cost/Schedule Summary for
Remedial Alternatives ..................
Summary of Action-Specific ARARs .......
Summary of Contaminant-Specific ARARs ..
Alternative 5 - Natural Stabilization
Cost Sheets ...........................
Final Cap Components
..................
vi
PAGE
58
60,61
65
68
71
92
93
95
96
119,120
140
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MAXEY FLATS DISPOSAL SITE
FLEMING COUNTY, KENTUCKY
SECTION 1.0 - SITE LOCATION AND DESCRIPTION
1.1
Location
The Maxey Flats Disposal Site (MFDS) is located on County Road
1895, approximately 10 miles northwest of the City of Morehead,
Kentucky and approximately 17 miles south of Flemingsburg in
eastern Fleming County. Figures 1 and 2 illustrate the site
location and site vicinity. The MFDS itself occupies 280 acres
of land. Approximately 4.8 million cubic feet of low-level
radioactive waste is buried in an approximate 45-acre area,
designated as the Restricted Area. Approximately 27 acres
within the Restricted Area have been used for the construction
of 52 disposal trenches. The Restricted Area also contains
storage and warehouse buildings, liquid storage tank buildings,
gravel driveways and a parking area. Figure 3 depicts the
trenches, trench sumps, and structures within the Restricted
Area as well as the extent of a polyvinylchloride (PVC) cover
over the 27-acre trench disposal area.
1.2
DemoaraDhics
Approximately 57 residential structures exist within a 1.0 mile
radius of the MFDS, housing approximately 152 persons. In an
area between 1.0 and 2.5 miles from the MFDS, 192 residential
structures house approximately 511 persons. Therefore, an
estimated total of 663 persons live within 2.5 miles of the MFDS
(This 2.5 mile radius is hereafter referred to as the study
area). Of the estimated 663 persons, an estimated 148 (22.3
percent) are women of childbearing age (15 to 44 years old) and
an estimated 148 (22.3 percent) are children (under the age of
14) .
Within a one-half mile radius of the MFDS, there exist
approximately 11 residences. The actual population of this area
is 25 people, 14 male and 11 female. Of the eleven females,
seven are of childbearing age. Only two children are present in
the population.
1 - The PVC cover
covers the access
slightly outdated
currently c9vered
over the trench disposal area currently
road between the trenches; thus, Figure 3 is
and does not'reflect all of the areas
by the PVC liner.
-------
NOTE : ADAPTED FROM KENTUCK Y
OFFICIAL HIGHWA Y MAP
LOCATION OF MFDS
WITHIN KINTUCKY NOT T0 SCAL|
SCALE IN MILES
MAXEV FLATS RI REPORT
MAXEY FLATS SITE RI/FS
EBASCO SERVICES INCORPORATED
MAXEY FLATS DISPOSAL SITE
LOCATION MAP
FIGURE 1
-------
EXPLANATION
MFDS RESTRICTED AREA
—— MFOSPROPERTY BOUNDARY
1000 0 1000 2000 3000
253
SCALE IN FEET
MAXEV FLATS m
MAXEY FLAT! SiTf RI/FS
EBASCO SERVICES INCQRPQR A TE
MAXEY FLATS DfSPOSAL SITE
VICINITY MAP
-------
EXPLANATION
I TNfNCN
f-~\ APTBOXIMAIl SOUNOABY
LJ O> 1RIMCM
I I N( ( I INI AND lt(XIN(l*HT
(II NtSTftiClfO ANtA
I""™! Af'PMf >XtMAH AHtAS
— * eve
UMiMlfll
MAXiĄ »lAfS f
MAXIV FIATS SITE HI/> S
I DA-.10 SI BVICf S INCOnrOMATiD
i CJCATIOM Of TffENCHES,
IHl NCM SUMPS AND BUILDINGS
IN HI SIHICIH) AHtA
O
A
ro
1-1
O
3
(U
OQ
0)
-------
Determination - Page 5
The MFDS study area population represents approximately 5.3
percent of the total Fleming County population. The projected
population of the 2.5 mile radius study area will increase from
663 persona in 1985 to a projected population of 767 in 2020, an
increase of approximately 15 percent. Additionally, a projected
population of 171 women of childbearing age and 171 children
will reside in the study area surrounding the MFDS by the year
2020.
1.3
TOPoQraphy
The MFDS is located in the Knobs physiographic region of
Kentucky, an area characterized by relatively flat-topped ridges
(flats) and hills (knobs). The MFDS is located on a spur of
Maxey Flats, one of the larger flat-topped ridges in the region.
The site is bounded by steep slopes to the west, east, and south
and is approximately 350 feet above the adjacent valley
bottoms.
1.4
Land Use
The land surrounding the MFDS is primarily mixed woodlands and
open farmland. A number of residences, farms, and some small
commercial establishments are located on roadways near the site.
The two nearest municipalities, the cities of Morehead
(approximately 10 miles southeast of the MFDS) and Flemingsburg,
Kentucky (approximately 17 miles northwest of the MFDS) have
populations of 7,196 and 2,721, respectively. The closest major
cities are Lexington to the west, and Huntington, West Virginia,
to the east, both about 65 miles from the MFDS.
Transportation in the immediate vicinity of the site
a network of secondary roadways, the routes of which
dictated by the local topography of relatively level
valleys and steep plateau slopes.
The region around the site is rural in character, primarily due
to topographic restrictions that limit access to the area and
the shortage of land available for development. In the
immediate vicinity of the MFDS, within one-half mile,
approximately one dozen homes are located along the unpaved
roads at the base of the site in Drip Springs Hollow and along
Rock Lick Creek, and on top of the plateau along Maxey Flats
Road. The slopes in the vicinity of the MFDS are covered mostly
with mixed evergreen and deciduous forest land. Wooded areas in
the region provide a supply of hardwood timber for the local
sawmills and logging industry.
is based on
are
stream
-------
Determination - Page 6
Four small family farms are loc~ted within a one-half mile
radius of the site. These farms raise beef cattle, swine,
goats, and sheep for meat and sale; poultry for eggs; tobacco
for sale; and hay and silage as food for their livestock. In
addition to the farms, most of the local residences have small
vegetable gardens for their private use. Table 1 summarizes the
land use within a 2.5 mile radius of the MFDS.
The Maxey Flats region has a public water supply system that is
operated by the Fleming County Water Association. Essentially
all residents in the area are served by this water system, much
of which was installed in 1985. The extent of the water supply
system is illustrated in Figure 4.
There are no large-scale commercial and industrial developments,
or higher density residential developments in the area within
2.5 miles of the site. In summary, the area surrounding the
MFDS is best characterized as a rural, undeveloped area
distinguished by low-density housing and rugged topography.
The limited employment base of the area, along with the limited
roadway and utilities access, makes large-scale economic
expansion in this region unlikely. Future land use can be
expected to follow the same historical patterns for the area:
small family farms, crop raising, logging activities and
moderate growth in population.
1.5
Natural Resources
1.5.1 - Surface Water
Billslope runoff at the MFDS typically travels in narrow, high
gradient, steep walled channels. These drainage channels
connect to the perennial streams that flow along the base of the
plateau at the periphery of the MFDS area. These streams, Drip
Springs, No Name, and Rock Lick Creeks, flow through relatively
level valleys bordered by steep hillslopes. Drip Springs Creek,
located on the west side of the site, and No Name Creek, located
on the east side of the site, flow into Rock Lick Creek to the
southwest of the site. Rock Lick Creek flows into Fox Creek
approximately two miles southwest of the MFDS. Fox Creek flows
into the Licking River, approximately 6.5 miles west of the
MFDS, which in turn empties into the Ohio River near Cincinnati,
Ohio, approximately 100 miles from the MFDS.
The perennial streams at the base of the plateau are used as
freshwater supplies for livestock raised in the valleys. Fox
-------
1----
Determination - Page 7
TABLE 1
ACREAGE-TABULATION FOR THE AREA WITHIN 2.5 MILES OF THE MFDS
Land Use
Total Acres
Percentage of Primary
Study Area
Residential
132
Other Urban or
Built Up Land
44
1.0
0.3
Cropland and Pasture
Brush Covered Land
4,885
Evergreen Forest Land
Deciduous Forest Land
167
254
39.6
1.3
2.1
597
4.8
Mixed Forest Land
6,128
Streams
161
49.6
1.3
Primary Study Area
12,368
100
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WA TER DISTRIBUTION LINE
. MAXEY flATS AI AEPOAT
MAXEY flATS SITE RI/FS
END OF WA TER DISTRIBUTION LINE
APPROXIMA rE MfOS PROPER TY BOUNDARY
EBASCO SERVICES INCORPORATED
c:J
MfDS RESTRICTED AREA BOUNDARY
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FIGURE
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Determination - Page 9
Creek is also used for light recreational fishing. The Licking
River is used both for recreational purposes and as a source of
public drinking water through municipal water systems upstream
and downstream of the MFDS. The nearest municipal water intake
downstream of the MFDS on the Licking River is located
approximately 54 miles from the site.
1.5.2 - Geology and Ground Water
Potential geological resources in the area of Fleming County
around the MFDS include building stone, clay and shale,
petroleum, oil shale and ground water. With the exception of
small amounts of building stone and ground water for private
residential use, these geological resources are currently not
being exploited.
Ground water resources in the area are very limited, with
residential supplies generally available only in the valley
bottoms. Ground water quality in the area is generally poor.
Residents in the immediate vicinity ,of the MFDS have been on
public water supply since 1985. Prior to 1985, water was
typically obtained from shallow dug wells which reportedly
supplied sufficient quantities of water for household use.
1. 5 . 3 - Biota
The region surrounding the MFDS includes many woodlots that are
periodically logged for timber. The wooded areas in this region
are classified as deciduous, evergreen, or mixed forest land.
The hillslopes adjacent to the MFDS are primarily deciduous and
include hickories, oak, ash, maple, black gum, tulip-poplar, and
beech. Because much of the hillslopes are privately owned, and
logging is an active industry in the immediate area, it is
possible that the standing timber on these slopes could be
harvested in the future.
Wildlife'species common to the MFDS area are those associated
with the oak-hickory forest of the ridge slopes, the adjacent
farmlands, or a mix of these two habitats. This mix benefits
such game species as white-tailed deer, woodchuck, opossum, fox
squirrel, and migrating woodcock, as well as furbearers such as
red fox, gray fox, long-tailed weasel, raccoon, and striped
skunk. Rough grouse and gray squirrel are also hunted in the
more extensively wooded areas., During late autumn and winter,
numerous Canada geese, as well as mallards, wood duck,
green-winged teal, and other game waterfowl feed on open crop
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Determination - Page 10
lands of the region. The acorn and hickory mast produced on the
hillslopes of the MFDS probably constitutes an important part of
the diet for white-footed mice, deer, squirrel, and turkey.
Several species of sport fish that are native to the Licking
River drainage have been collected from Fox Creek including
muskellunge, channel catfish, rockbass, spotted bass, largemouth
bass, white crappie, various sunfish, and sauger.
There are no federal threatened or endangered species known to
exist within the vicinity of the MFDS. Blazing Star, a plant
species listed as being of special concern by the Kentucky
Preserves Commission, does occur within a 2.5 mile radius of the
site, but would not be threatened by any physical activities at
the MFDS due to its distance (approximately 1.5 miles) from the
site.
1.6
Climate
The climate of the MFDS area is classified as Temperate
Continental. The summers are warm with temperatures above
900F occurring approximately 30 days per year. The winters
are cold but not extreme, as temperatures below zero generally
occur only a few times per year. Temperatures above 1000F and
minimum temperatures as low as -22oF have been recorded in the
region.
Average annual precipitation in the MFDS area is approximately
44 inches. A maximum 24-hour precipitation total of 5.8 inches
would be expected for a 100-year return period in the area.
However, the possibility exists for extreme rainfall events to
exceed the 100 year maximum in the MFDS area. Snowfall in the
area averages approximately 18 inches per year with the highest
monthly average occurring during January.
Wind distribution data for the MFDS area reveals a fairly even
annual distribution of wind direction, with the greatest
frequency from the south and southwest directions. The average
wind speed observed over a 10-year period was 9.7 miles per
hour. Average wind speeds are greater during the spring and
winter seasons and the greatest percentage of calm wind
conditions occur during the summer months. A maximum wind speed
of 90 miles per hour associated with a return period of 100
years is estimated for the MFDS area.
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Determination - Page 11
SECTION 2.0 - SITE HISTORY AND ENFORCEMENT ACTIVITIES
In 1954, the u.S. Congress passed the Atomic Energy Act which
provided for the development and utilization of atomic energy
for peaceful purposes. In 1959, Congress amended the Atomic
Energy Act of 1954 to provide for State participation in certain
regulatory controls on the use of atomic energy. Provisions
were made for the federal government to enter into agreements
with states on such participation.
As part of a program to encourage nuclear industry in Kentucky,
the Kentucky General Assembly created the Division of Nuclear
Information in the Kentucky Department of Commerce. The
Kentucky General Assembly then passed legislation in 1960 which
provided power to the Governor to enter into an agreement with
the federal government for the transfer of certain regulatory
powers in atomic energy to Kentucky. Also in 1960, the Governor
of Kentucky charged the Department of Health with the
responsibilities of providing regulations for the licensing of
radioactive materials. The Kentucky General Assembly passed
legislation in 1962 enabling the Commonwealth of Kentucky
(Commonwealth) to purchase lands for the disposal of radioactive
waste; the land to be owned and controlled in perpetuity by the
Commonwealth. Also in 1962, the Commonwealth became the first
state to sign an agreement with the federal government for the
transfer of certain regulatory powers in atomic energy and,
thus, became what is referred to as an "agreement state". In
this agreement, authority was vested in the Commonwealth to
license the disposal of low-level radioactive waste. The Atomic
Energy Commission retained authority to license the burial of
waste from the reprocessing of spent nuclear fuel.
The Kentucky Division of Nuclear Information was succeeded by
the Division of Atomic Development, whose responsibilities were
then transferred to the newly created Kentucky Atomic Energy
Authority in 1962, which eventually became the Kentucky Science
and Technology Commission. In 1962 a commercial organization,
Nuclear Bngineering Company, Inc. (NECO), purchased 252 acres of
land in Pleming County, Kentucky, in a knob area known as Maxey
Flats and submitted an application to the Kentucky Department of
Health for a license to bury radioactive waste at Maxey Flats.
Following site evaluations and approval, the Commonwealth issued
a license, effective January 1963, to NECO for the disposal of
solid by-product, source and special nuclear material at the
proposed site, and a contract was negotiated between the
Commonwealth (Kentucky Atomic gnergy Authority) and NECO.
Issuance of. this license was contingent upon conveyance of the
title of the $ite to the Commonwealth in accordance with state
and federal regulations.
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Determination - Page 12
The Kentucky Atomic Energy Authority, in turn, leased this tract
of land back to NECO for a twenty-five year period with the
option for NECO to renew the lease for another twenty-five year
period thereafter. The lease agreement provided for the
establishment of a perpetual care fund, requiring a cost per
cubic foot of waste disposed, to be paid to the Commonwealth by
the operator (NECO).
I.
I
The first radioactive material was disposed at the Maxey Flats
Disposal Site in May 1963. From May 1963 to December 1977, NECO
managed and operated the disposal of an estimated 4,750,000
cubic feet of low-level radioactive waste (LLRW) at the MFDS.
In order to protect public health and the environment from
exposure, low level radioactive waste must be isolated during
the time that its radioactivity is decaying. To achieve this
isolation at the MFDS, low level radioactive waste was disposed
at the site using shallow land burial. The waste was disposed
of in 46 large, unlined trenches (some up to 680 feet long, 70
feet wide and 30 feet deep) which cover approximately 27 acres
of land within a 45-acre fenced por~ion of the site known as the
Restricted Area. However, "hot wells" were also used at the
MFDS for the burial of small-volume wastes with high specific
activity. Most of the "hot wells" are 10 to 15 feet deep,
constructed of concrete, coated steel pipe or tile, and capped
with a large slab of concrete.
The trench wastes were deposited in both solid and
solidified-liquid form. Some wastes arrived at the site in
containers such as drums, wooden crates, and concrete or
cardboard boxes. Other wastes were disposed of loosely. Fill
material (soil), typically 3 to 10 feet in thickness, was then
placed over the trenches to serve as a protective cover. After
1977, six additional trenches were excavated for the disposal of
material generated on-site, bringing the total number of
trenches at the site to 52.
Environmental monitoring, in 1972, by the Kentucky Department of
Health (Department for Human Resources) revealed possible
migration of radionuc1ides from the Restricted Area. This
monitoring indicated that water entering the trenches had become
the pathway by which radioactive contaminants, primarily tritium
. which is a radioactive form of hydrogen, were beginning to
migrate out of the disposal trenches. A special study of the
site was conducted by the Commonwealth of Kentucky in 1974 to
determine whether the MFDS posed any contamination problem. The
-------
Determination - Page 13
study confirmed that tritium and other radioactive contaminants
were migrating out of the trenches and that some radioactive
material had migrated into unrestricted areas. Various other
studies of the MFDS were initiated by the u.s. EPA, u.s. Nuclear
Regulatory Commission, u.s. Geological Survey, and the Kentucky
Department for Human Resources during the 1970's and 1980's.
The Kentucky Science and Technology Commission was abolished in
1976 and the perpetual care and maintenance responsibilities for
the MFDS were transferred to the Kentucky Department of Finance.
In 1977, during construction of Trench 46, it was determined
that leachate was migrating through the subsurface geology
(approximately 25 feet below ground surface). Subsequently, in
December 1977, the Commonwealth ordered NECO to cease the
receipt and burial of radioactive waste.
In 1978, the Commonwealth and NECO entered into an agreement
under which NECO's twenty-five year contract/lease was
terminated. After disposal operations ceased and the lease with
NECO was terminated, NECO's license remained in effect, with
certain modifications, until 1979 at which time the license was
transferred to the Commonwealth. The Commonwealth's operational
responsibilities at the MFDS were transferred from the
Department of Finance to the Department for Natural Resources
and Environmental Protection in 1979, with regulatory
responsibilities remaining with the Kentucky Department for
Human Resources. Upon transfer of NECO's license to the
Commonwealth, private companies such as Westinghouse Electric
Corporation (the current site custodian) were hired to stabilize
and maintain the site. Stabilization and maintenance activities
have included installation of temporary covers over an
approximate 27-acre trench disposal area, surface water
controls, subsidence monitoring and contaminant monitoring.
From 1973 through April, 1986, an evaporator was operated at the
site as a means of managing the large volume of water
infiltrating the disposal trenches as well as waste water
generated by on-site activities. The evaporator generally
operated 24 hours per day, approximately 250 days of the year
until 1986, when it was shut down. The evaporator processed
more than 6,000,000 gallons of liquids, leaving behind
evaporator concentrates which were then stored in on-site,
above-ground tanks. Evaporator concentrates were eventually
disposed of by the Commonwealth in Trench 50, which was
constructed in 1985 and 1986. .
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Determination - Page 14
In 1981, a polyvinylchloride (PVC) cover was placed over the
disposal trenches as a means of minimizing the infiltration of
rainfall into the trenches. Liquid storage tanks remained
on-site for future storage of site-generated liquids and
emergency trench overflow pumping operations. Those steps,
however, were temporary. .
In 1983, at the request of the Commonwealth, EPA began the
process of determining whether the MFDS would be eligible for
remediation under CERCLA. In 1984, EPA proposed the MFDS for
inclusion on the National Priorities List (NPL) of hazardous
waste sites to be addressed under the federal Superfund Program
and, in 1986, this listing was finalized.
The MFDS was a primary disposal facility for low-level
radioactive waste in the United States during its period of
operation. As a result, the list of parties potentially liable
for site cleanup, known as poten2ially Responsible Parties
(IPRPs"), includes more than 650 rad~oactive waste generators
and transporters. The generator PRPs include many private
companies in the nuclear industry as well as numerous hospitals,
research institutions and laboratories. Several federal
agencies, including the U.S. Department of Defense (DOD) and
U.S. Department of Energy (DOE) are also generators of iite
waste. The Commonwealth of Kentucky, as the site owner and a
generator, is also a PRP.
In 1986, EPA issued general notice letters notifying 832
Potentially Responsible Parties of their potential liability
with respect to site contamination and offering them an
opportunity to conduct and fund a Remedial Investigation/
Feasibility Study (RI/FS) of the MFDS. In March 1987,
eighty-two PRPs signed an Administrative Order by Consent (EPA
Docket No. 87-08-C) to perform the RI/FS. This group of PRPs
2 - If each facility or division of a PRP is treated as a
single entity, the number of PRPs totals more than 800.
3 - Some of these radioactive waste generators also disposed
of chemical wastes at the MFDS.
4 - The Commonwealth was required by state and federal
reaulations to own the MFDS nronertv. as is reauired for all
low":i~';'ei--~adio~cti';'~-w~~t~ di~p~s~l' sites. .
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Determination - Page 15
formed the Maxey Flats Steering Committee (Committee). The
Committee has conducted and partially funded the technical work
required for the Remedial Investigation/Feasibility Study
performed at the site. The largest portion of costs incurred in
conducting the RI/FS was paid by DOD and DOE, both named as PRPs
but not members of the Maxey Flats Steering Committee.
In November 1988, EPA notified the PRPs of an imminent threat to
public health, welfare and the environment posed by the
potential release of liquids stored in the on-site storage
tanks. The threat arose from the presence of eleven 20,000
gallon tanks in the tank farm building that had been present
on-site for 10 to 15 years and whose structural integrity was of
great concern. The unstable condition of the filled-to-capacity
tanks posed an immediate threat to public health and the
environment. The PRPs declined the offer to participate in the
removal actions~ thus, on December 19, 1988, EPA initiated phase
one of the removal.
Phase one consisted of the installation of heaters in the tank
farm building to prevent the freezing, and subsequent rupturing,
of tank valves and fittings which were submerged under water
that had infiltrated the tank farm building. Phase one, which
was completed in February 1989; also included the installation
of additional storage capacity on-site.
Phase two of the removal was initiated by EPA in June 1989.
Phase two began with the solidification of approximately 286,000
gallons of radioactive liquids stored in the eleven tanks and of
water that had accumulated on the floor of the tank farm
building. Solidification activities were completed in November
1989 and resulted in the generation of 216 blocks of solidified
tank and tank floor liquids. Burial of these blocks, which were
stored on-site and above-ground, was initiated in August 1991
with completion scheduled for November 1991. Solidification
blocks will be disposed in a newly constructed trench within the
MFDS Restricted Area.
The Remedial Investigation Report for the MFDS was approved by
EPA in July 1989. The Feasibility Study for the MFDS was
finalized and, along with the Administrative Record file for the
site to date, was submitted to the public in May 1991.
-------
I
Det~rmination - Page 16.
SECTION 3.0 - HIGHLIGHTS OF COMMUNITY PARTICIPATION
Community interest and concern about the MFDS began in 1963
shortly after approximately 252 acres of land was purchased for
radioactive waste disposal operations. Area residents reported
initially that they were not informed of plans for the property
and that authorities provided little or no opportunities for
community input to the decision-making process. Area residents
also were concerned with methods used to place wastes in the
disposal trenches. When the Commonwealth released its 1974
study of the site, findings of elevated radionuclide levels drew
the attention of local and national media. In response,
citizens in the site community formed The Maxey Flats Radiation
Protection Association to investigate site conditions and
publicized the need for protection of nearby residents.
Organized citizen concern declined for a period after the
Commonwealth closed the site to the receipt of wastes in late
1977.
Concern resurfaced in 1979 when area residents learned that
tritium was escaping from an evaporator used at the site to
reduce the volume of liquids that had accumulated from trench
pumping operations. A second group, called the Concerned
Citizens for Maxey Flats, formed to organize citizen concerns
regarding the tritium releases. This group requested that
public water be provided to residents in the Maxey Flats site
vicinity. Public water was extended in 1985, by the Fleming
County Water Association, after which organized community
efforts again subsided. Community members remained concerned,
however, that the site should be cleaned up.
The present-day Maxey Flats Concerned Citizens, Inc. (MFCC) has
been very active throughout the Remedial Investigation (RI) and
Feasibility Study (FS). The MFCC submitted an application to
EPA for a Technical Assistance Grant (TAG) in 1988, and on
January 13, 1989, EPA provided $ 50,000 to the MFCC for the
purpose of hiring technical advisors to help the local community
understand and interpret site-related technical information and
advise the community on its participation in the decision-making
process. .
A Community Relations Plan for the MFDS was developed and
finalized in 1988, which described the proposed community
relations activities, along with a Work Plan describing the
technical work to be performed as part of the RIfFS. Pursuant
to the Community Relations Pla~, information repositories were
established into which EPA could place information to keep the
public apprised of developments related to the MFDS. Due to the
proximity of the site to both the cities of Morehead and
Flemingsburg, and the locations of interested citizens, two
-------
Determination - Page 17
information repositories were established for the MFDS; one
located in the Fleming County Public Library, 303 South Main
Cross Street, Flemingsburg, KY 41041; and the second, located
in the Rowan County Public Library, 129 Trumbo Street, Morehead,
Kentucky, 40351.
Beginning with the Community Relations Plan and the RIfFS Work
Plan in February 1988, a number of site-related documents have
been placed in the repositories. A draft version of the RI
Report was placed in both repositories in November 1988 and the
final RI Report was placed in the repositories in September
1989. The revised draft Feasibility Study Report was provided
to the MFCC in September 1989; revision pages to the revised
draft FS Report were also provided to the MFCC in December 1989,
and the final FS Report was submitted to the MFCC and to both
information repositories in June 1991. The Administrative
Record file, which is a compilation of documents and information
considered during the selection of the site remedy, was placed
in the Fleming County Public Library on June 12, 1991, and on
June 14, 1991 at the Rowan County Public Library.
In addition to the technical reports and documents placed in the
repositories, fact sheets summarizing particular site
developments have periodically been issued to help keep the
public informed about activities at the MFDS. Fact sheets were
issued by EPA in September 1987, July 1989 and May 1991.
Additionally, fact sheets have been periodically distributed by
the MFCC and the Maxey Flats Steering Committee throughout the
RIfFS process. On May 30, 1991, EPA mailed more than 600
Proposed Plan Fact Sheets to members of the community,
interested parties, and Potentially Responsible Parties,
informing them of EPA's preferred remedy and announcing the
holding of a public meeting on June 13, 1991.
A number of meetings have also been held regarding developments
at the MFDS. EPA held a citizen's information meeting in
January 1988, and again in September 1988 at the Fox Valley
Elementary School in Wallingford, Kentucky to discuss the
activities to be performed as part of the RIfFS. A meeting was
held with the MFCC in September 1989 to discuss the development
of remedial alternatives in the Feasibility Study. A citizens
rally was put on by the MFCC in October 1989 to discuss the RI
. findings, risk assessment conclusions, and remedy options. In
October 1990, the MFCC sponsored a forum on the MFDS (which
included EPA, Commonwealth and PRP participation) to discuss the
site status. On May 22, 1991, 'EPA and the Commonwealth of
Kentucky held a meeting with landowners adjacent to the MFDS for
-------
Determination - Page 18
the purpose of discussing the buffer zone component of the
preferred remedy and, on June 13, 1991, EPA sponsored a public
meeting at the Ersil P. Ward Elementary School in Wallingford,
KY to discuss EPA's preferred remedy for site cleanup as wel~ as
other alternatives considered during the FS process. Press
conferences and site tours were conducted in October 1987 and
June 1991.
The public meeting on the preferred remedy/Proposed Plan, which
was held on June 13, 1991, initiated a public comment period
which concluded on August 13, 1991. A press release and three
local newspaper notices were published announcing the meeting.
Prior to the initiation of the public comment period, EPA
extended the usual 30-day public comment period on the preferred
remedy/Proposed Plan to 60 days due to site complexity, numerous
issues involved, number of documents in the Administrative
Record file, and a' high level of community interest at the site.
A response to the comments received during the public comment
period is included in the Responsiveness Summary, which is
Appendix A to this Record of Decision. A transcript of the June
13, 1991 public meeting on the preferred remedy/Proposed Plan is
included as Appendix C of this Record of Decision.
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Determination - Page 19
SECTION 4.0 - SCOPE AND ROLE OF RESPONSE ACTION
The selected remedy presented in this decision document serves
as the first and final remedial action for the Maxey Flats
Disposal Site. The treatment, containment, engineering and
institutional control components of the selected remedy will
reduce the potential risks from the site to an acceptable level
upon remedy completion. As part of the selected remedy, EPA
will require further data collection and analyses to determine
the necessity of a horizontal flow barrier as a component of the
remedy. If, based on this data collection and analyses, EPA
determines that a horizontal flow barrier is necessary, it will
be installed as part of this remedial action. The type and
location of the barrier will be determined by EPA in
consultation with the Commonwealth.
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Determination - Page 20
SECTION 5.0 - SUMMARY OF SITE CHARACTERISTICS
The Remedial Investigation (RI), which was initiated at the
Maxey Flats Disposal Site (MFDS) in 1987, included the
collection of more than 700 samples at, and adjacent to, the
MFDS, from environmental media such as trench leachate, ground
water, soil and soil water, surface water, and stream sediment.
The samples were analyzed for a variety of radiological and
non-radiological (chemicals, metals, etc.) constituents. A
summary of the sample matrix, number of samples, and type of
sample analyses performed during the Remedial Investigation is
presented in Table 2.
The environmental analyses conducted during the RI complemented
the extensive sampling activities previously performed by the
Commonwealth, the united States Geological Survey and national
laboratories. The data collected prior to the RI was utilized
in the RI to the exent practicable. Sampling activities by the
Commonwealth are still continuing.
5.1
Nature and Extent of Contamination
Most of the waste disposed of at the MFDS was in solid form,
although some container-enclosed liquids and solidified liquid
wastes were accepted during the earlier years of site
operation. The wastes were in a variety of containers including
cardboard or fiberboard boxes, wooden crates, shielded drums or
casks, and concrete blocks. Wastes of low specific activity
which were buried in the Restricted Area include paper, trash,
cleanup materials and liquids, packing materials, protective
apparel, plastics, laboratory glassware, obsolete equipment,
radiopharmaceuticals, carcasses of animals, and miscellaneous
rubble. Higher activity waste buried in the Restricted Area
included sealed sources, irradiated reactor parts, filters,
ion-exchange resins, and shielding materials. Transuranic
waste, generally associated with glove boxes, gaskets, plastics,
rubber tubing, paper, and rags, was also buried at the MFDS.
Information on the types and quantities of chemical wastes
buried at the MFDS was generally not recorded at the time of
waste burial. However, some Radioactive Shipment Records ~ote
the disposal of "Liquid Scintillation Vials" ("LSVs"). LSVs are
small vials, generally containing a solvent and a radioactive
constituent. LSVs are used in laboratories to count the amount
~f TJ'IIn;n;!il"'!r;v;rv ;n l;!innr;!irnTV a;!imnl"'A fnr d;J'IIt7nnR~;1'! ~F!gtg.
-- ------------~ --- ---------.6 --1:"'--- --- ---~------- -----.
environmental monitoring and in other industrial and medical
applications. The principal hazardous organic constituents
associated with liquid scintillation fluids are toluene and
xylene.
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Determination - Page 21
TABLE 2
REMEDIAL INVESTIGATION SAMPLING AND ANALYSIS PROGRAM
SAMPLE NUMBER OF CHEMICAL RADIONUCLIDg
MATRIX SAMPLES COLLECrED ANALYSESa ANALYSES
LEACHATE
15 Trench Sumps 15 + 1 dupc Complete, RCRA H-3,IG,EXP,C-14
MONITORING WELLS
8 Producing Wells 16 + 2 dup Complete, RCRA H-3,IG,EXP,C-14
2 USGS Wells 4 Complete, RCRA H-3, IG,EXP ,C-14
1 Producing
Background Well 2 Complete, RCRA H-3,IG,EXP,C-14
BOREHOLE SAMPLES H-3t
Soil and Rock 261 none
SOIL
Round 1 218 + 12 dup none H-3
Round 2 132 + 7 dup none H-3,IG
Round 2
(select samples) 16 + 2 dup Complete, RCRA* H-3,IG
Food Crop Samples 5 + 1 dup CQmplete H-3,IG
Background 3 Complete H-3,IG,EXP
dOlL WATER
1 Producing
Well Point 2 + 2 dup Complete, RCRA H-3,IG,EXP
SURFACE WATER
Surface Water 20 + 2 dup Complete. H-3,IG
Background SW 2 Complete H-3,IG,EXP
STREAM SEDIMENT
Sediment 20 + 2 dup Complete H-3,IG
Background Sed. 2 Complete H-3,IG,EXP
------------------------------------
a)
Chemical Analyses:
Complete - Target Compound List (TCL) organic chemicals
Target Analyte List (TAL) inorganic chemicals
- pB, sulfide screen, ignitability screen
- pB, sulfide screen, ignitability screen,
acid reactivity, base reactivity, water reactivity
RCRA*
RCRA
b)
Radionuclide
B-3
B-3t
IG
EXP
Analyses:
Tritium
Tritium analyzed by on-site laboratory
Isotopic Gamma
Expanded: Sr-90 and gross alpha; if gross alpha was
greater than 0.015 pCi/ml, then analyses for Ra-226,
and isotopic Pu and U were also performed
Carbon-14
C-14 -
c)
dup - duplicate sample
-------
Determination - Page 22
The total volume of waste received from off-site and buried at
the MFDS has been estimated at approximately 4.8 million cubic
feet. Of this volume, the activity of by-product material alone
(material that has become radioactive by neutron activation in
nuclear reactors), disposed of at the MFDS, has been estimated
at 2.4 million Curies. Much of this material was reported as
mixed fission products; thus, the total activity from by-product
waste may be underestimated. Other wastes disposed of at the
MFDS include Special Nuclear Material (Plutonium, Uranium-233
and enriched Uranium-235) and source material (Uranium and
Thorium, not including Special Nuclear Material).
In addition to the wastes received from off-site sources,
on-site operations have generated material which includes waste
from ground surface grading, trench leachate pumping, evaporator
operation, and general waste handling. Wastes generated from
on-site activities have been disposed of, in solid form, in
newly constructed trenches within the site's Restricted Area.
Trenches 48 and higher contain waste generated from on-site
activities. Trench dimensions and volumes are presented in
Table 3.
5.1.1 - Trench Characteristics
The RI estimated that a total of approximately 2.8 million
gallons of leachate are in the disposal trenches. The RI, as
well as previous investigations, concluded that there is a large
range of contaminant concentrations in samples collected from
trenches in different parts of the Restricted Area.
Additionally, site records indicate that samples (tritium, gross
alpha and beta particle analyses) from the same trench sump
yield varying concentrations at different times.
Fifteen trench sumps were sampled during the RI. Trench sump
sampling locations are illustrated in Figure 5. The trench
leachate was found to contain a variety of radionuclides (of
which tritium is the most predominant), as presented in Table
4. In general, the non-radiological, chemical concentrations in
trench leachate samples were low. The dominant chemical
constituents detected were solvents, chelating agents, phthalate
esters, hydrocarbons, phenolics, ethers, and carboxylic acids.
Concentrations of chemical constituents ranged from non-detect
. to less than 10 ppm. (See Table 5.) A review of pre-RI trench
data indicates that the total organic carbon (TOC) concentration
was variable among the trenches sampled, with Toe values ranging
from 460 to 3300 ppm. The results of inorganic sample analyses
are presented in Table 6. In general, trench leachate appeared
-------
Jetermination - Page 23
TABLE 3
TRENCH DIMENSIONS. VOLUMES AND BURIAL PERIODS1
Trench
Number
Dimensions
LxWxD
(feet)
Trench
Volume
(cu ft x 1000)
Trench
Number
Dimensions
L x W x D
(feet)
Trench
Volume
(cu ft x 1000)
1 162 x 10 x 15 24 26 300 x 50 x 102 150
15 78 x 25 x 15 29 27 350 x 70 x 18 441
2 79 x 25 x 15 30 28 350 x 70 x 18 441
3 275 x 15 x 15 62 29 350 x 70 x 18 441
4L 44 x 15 x 15 10 30 360 x 75 x 22 594
55 68 x 15 x 14 14 31 360 x 76 x 22 602
6L 44 x 15 x 14 9 32 350 x 70 x 223 539
7 242 x 15 x 15 54 33L 350 x 50 x 104 150
8L 50 x 15 x 13 10 34 140 x 24 x 10 34
9L 32 x 15 x 12 6 35 300 x 70 x 20 420
.0 300 x 30 x 15 135 36 200 x 20 x 18 72
115 300 x 30 x 12 108 37 200 x 20 x 18 72
12L 35 x 10 x 8 3 38 200 x 50 x 17 68
13L 15 x 10 x 8 1 39 200 x 50 x 16 160
14L 15 x 9 x 5 1 40 686 x 70 x 30 1,441
15 300 x 50 x 12 180 41 255 x 20 x 10 51
16L 15 x 10 x 8 1 42 650 x 70 x 30 1,365
17L 30 x 15 x 10 5 43 614 x 50 x 30 921
18 275 x 40 x 9 99 44 681 x 55 x 30 1,124
195 300 x 40 x 10 120 45 145 x 55 x 32 255
20 300 x 40 x 12 144 46 190 x 50 x 15 143
21L 300 x 42 x 15 189 47 150 x 34 x 15 77
22 300 x 20 x 12 72 48 100 x 40 x 15 60
23 300 x 60 x 10 180 49 200 x 30 x 15 90
24 300 x 50 x 10 150 50 65 x 45 x 20 58
25 300 x 30 x 11 99 51 43 x 46 x 15 30
1 - Source for information on Trenches 1 through 46, except Trench 34,
from Westinghouse Bittman Nuclear, Inc., 1984 and Zehner, 1983.
2 - East end of Trench 27 is deeper ~han west end.
3 - Actual trench area is estimated to be approximately 33 percent of the
areal dimensions. Depth is based on the average depth of sumps and
depth range in Zehner (1983).
4 - Source:
Photo Science, Inc., 1983.
-------
L-.
Det~rmination - PagŁ
FIGURE 5
.,";-
/7
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..~
,
1-'--;:-'r=;:"~T--r:'~:-'- ~-< ., -.,' -..<..-
. 'J' I, ,r -, r-- .'- ~:~ '-"'/""
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" ' , ,:: I I I ," ~ II "I "1':, [1 . -- '-.. --. --~)'~..,~.-
'If ,', , I I I , I,' I ' . -.' \
i I ;, \ I. "" ""."' I I . ; . "
, ' !:, I I : , I " I , f-12,;I, : , I ,: I " . I , ' .,
,., ~. i " \!, I' ,I " " I " !....,,' ~', I ' ,/
I' , ~t , " , " '" ,". / ,,~
,j~: \ 111.~:~',~::: .:1 ::U.~:r :a-.::~ . -,. '
v, 1: ' 'd" .,".tl ' :' '/.! I.,' ~ .,1 '
\ . \. --L__'!_J., ,~._,~u 1 : Lj'.' 1../- '.
, ., \ ; '.'. I:;.:---!...~'-f' -L..-.J ~~.. \ (: .~-
, . ~ r-l'- --,.___.L_.:J - . ,
~":::..h.:""l"ul i'-l;~~,-~r-:-if~;l f1f,~r'\r'-;"i1'nnn; '. '.:.'.__.... ... "
~, " ,.'," ", /I " . 'U-l111 I " II ',',1"'" '" ' . . ' 1
'". . "1 . '.', II, " I, , ,..)'" '", '"t,,'Il6i'~ - f::::J ',' .
""., 1-,: . , 1,:; ': .;: :. : '.,,: ',I' /"/\rll:n~. ,'" rl ~.'. ~,'
, ,.~.,". /1"1;.:I,~ W.tt:~! i.1 if ~/:,.M~~' ,.. i!,;[~,~-,.!. "-':-",-:J '"
" .J I '~I....J! _,I ,1--' ALl " ,. fA . I~.. .' :~. '1'\ rl'>,=- ..-- \ '
~ .' &':-":;i!"'~":"-=~~~~~L1'JJ:l,, c~.:."d ,=~k -'=' ',/
. . I -..., '. - -:--=' .~_J ' .~ ._.;~'.LJ. ~~. ---_.a.;- ~
, if' :::_~"t-' - . "'c-,...;.:.~-=:! :..- "",='- -b,;;-=-~-_-::_;
" r - ---"~':.",,,,,I.' 'J.... 4I-U -------, "
( oJ.", I~,. '-- 41-14. " J r-,
, ,"_o.zo-=-;.....-;", I "-", '-c.-.-~--,-- -------------j "
. '/' \'1':~-':'-, ,-_J -'I . ~._,:-:~~~=,.....-,~,-:.~~:-, ~-:-~'------1 ,~'J "
. -...,_..J" ...' ~"', "'. \:'n"- .~:'.:':=---.:..-::-=-~_-:~::!..' ".
/. I /---'--..-:.~"~ '. ~ ....-- --------,
, /" .......~J " . -." ' ,
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r-7~'7.::;::::":'::=-== ~ ',':?..'.." ::--:7'~--:"......~-~ 'J /
i """'~. i ,. . "., .'-;""F7 c ~~., or=~.:~ \~. =~-~~: '~'=-~ ;~.;-:-,. .'. . :,,--1 t/j
I...-- .........,....I ,- . .,. '\ .'
EXPLANATION
..
IRtNC.t SU...' SA...PlED DURING RI
'ROGII...... WI1I1TIIENCH NUMBER,
SUM' DESIGNA TlON
r, I'PPROX,......TE UOUNDARY 01
LJ TRENCII
-.- fENCElINE AND IOUNDARY
OF 'USTIUCTED AIIEA
~ IUllD'NG
"
/
.I
.'/
\.
, ~ . .;.. ',,'//.'" L.........I , . ,
,.,. - "
SCI'Ull/fElT
, MA.' Y fLAtS ". "'PO.n
MAIlEY fLA 11 alTE IIliU
-
EIASCO SERVICES INCO"'OR...HI1
,
'~~~,F- - .. --- TRENCIi SUMP SAMPLING LOCA liONS
., "
\, . 'GUilt J J
.
1011
lOll
JaIl
tOO
I
l
-------
Determination - Page 25
TABLE 4
....010..<1.1011 ... lI.tIC. ..At.1I .1. PtKIGtM .U"MU
CCClnun".' i8\l in 51'1'.)
IIIIU 18nl- ~ .JI:1L- J.I:.IL 1,.90 -1UJL 1.-21' u'lJJIl~ u 21., ".lJI ",.ZJI Pu.1191140
7.J -," - -'0 <0.' '.4"'0.' UO '/" 40 1.\'/-0.' 0.0100"0.- 0.16 1/' Q,OI 0.01/ .,.a,olu Q.I06 "'0.00 '.0""" '.0)4 0,0009-"0. ODO\
1.. -,, - -'0 <0.' "~'-8.' 181 ./ lu 9.9., .0.\ O. ""'-0.01:8 0.160-1 0.- e.OO9 ".D,DIU O. ". '1 '0.001 0.10'" 0 CIDl D.DCJOII" Q.OOQl
,,,-, .-,. - -'0 00.' O.t-,.O.' JOOO -"100 00.' 0._' 0.01 D.C)") '/' Q.Ol ~o. 001 0.008 ".a.GOt .. ./- 1 0.01 .,-D.Ck
'''-7 -,- - '00,-'0 <0.' 0.\"'0.' 1m ., 10 II .,oc. 0.\000"0.0\ o.~,. o.oor. 0.001 -/'0.001 0.00' '/-0.001 1.4 '/' 0.1 000 "'0.01
''''1 ,-,- ,- -It 1.01"'0.1IZ 1."'-0.1 .l1li .,. 10 00.' D.SlO./-I.al 0.60 -,. 0.01. 0.021.,-0.001 cO."" IIZ -"10 oO.Ql
I',' ,,-,- - -10 00.' 8.~/-8.' ".,.,. 0.' 4.)-,.0.2 .._,-8.001 D Oll-,- 0.1IOIt cD.CQOI. O,GICU./,O.GOIJ) .., -,. 1.1 . ""
J'.I -,- ,- -.. 4.1 1.1"'1.1 ,.. .,. n 4.4"-' 8.IMo,-..tOl 0 WO-" O.DOl -o.OOUS O.CIDOI"".aaos I.' .,- '.J I.J "'0.'
JJ., U-,- - -'8
-------
Determination - Page 26
TABLE 5
8f$UUS Of ORGANlf-f!IMICAl ANALYSf$ fOR '~fNC!-![AC~AII (RI PROGRAN ANAlYSfS)
(concentrat ionli in ppb)
1,1 1,2
Ethyl' Methvlen. Chi oro- Vinyl Chi oro- Dichloro- D I chi oro- Phthelate Naph- 2-Methyl 4-Methyl
SU8P ~ceton. It:nlen. Tolu.n. hl.n. benune cMorlde for. chloride Ithan. ethane 'Ih.n. nteu thelene phenol pllenol
07-2 <10 <5 <5 51 21 <5 <5 <10 <10 .5 <5 <10 "0 .10 .,0
07-9 <10 <5 <5 10j <5
-------
Determination - Page 27
TABLE 6
IlfSUl 1$ OF ,NORGAN,C ANAl'St1-f~IENC" IEACHAIE (I, PROGRAM ANAlY~
(concentrations In JPJ)
$lJIP At Sb Aa I. ,. Cd C. Cr Co . CU Ie Pb "II It1 "II Ni K $0 All Na II V In
07-2 400 460 .,0 ]]101 ., cS 28910 c10 c~O c~ 12280i cS 44~40 41 cO.2 :<40. I~61JO: ~.4r ciO 28~~00 -10 -~o 2Ji
07-9 c200 460 .,0 15957. 7.6.5 7J~0 19 <~O -~ NO 9.2r 64190 :14 <0.21 157; 1406JO, <~ clO 419800 -10 -~O 2()1
195-6 400 460 c10 1161. ., c5 10J80 14 <~O -~ 2JI20~ 17.6r 119520 ~o 0.2 n 1066. 20400 <~ <10 282400 -10 -~o J8!
195- 7 400 70 .,0 1850. c5 c5 4U~0 1~ <~O -25. 21800! 6.9r 168220 62 <0.2. 624' 45940: <5 <10 II) -10 (~O 4I6!
19$-8 c200 460 .,0 824 c5 <5 24J~0 n 86 150' 11110' 18.0r 171020 148, 0.5.n 1264: 2:1440, -~ <10 NO -10 (~O 206'
26-2 400 460 .,0 994 ., ., 10220 c10 c50 <25 14910 6.1! 90070 421 -0.2 78. J9910 <~ <10 290000! -10 -~o 2191
26-) .200 460 .,0 451 c5 c5 9670 16 CSO <25 9840 5.2' 161~0 46, <0.2 2~J: 514101 <5 <10 J660001 <10 <~O 121'
27-5 400 460 .,0 16270 c5 15' 199120 c10 c50 <~ 9J940 c5 2904JO 4490 <0.2 118 824801 <5 -10 5200001 - 10 -~O 9801
)2-:-' 400 460 12r 1164 ., .5 21040 42 c50 c25 9170: 7.1r 10924099400 cO.2 6J: 276090 <5 c10 1591JOO <10 (~O 221'
)2- 400 460 .10 10J8 c5 c5 18460 45 <50 c25 7810 <5 98600 79 <0.2 6J. 221270: <5 <10 IS9J500 <10 -50 1761
]2-Ł 400 460 20r 410 cS c5 10100 11 <~O <2~ 161O! -S 117890 62 <0.2 160! 1291601 -S 17! 1649JOO 45r -50 2111
J5-4 190 460 541r 1956 cS <5 24170 1.1 <50 -25 J~IIO! -5 246090 165 -0.2 76' 202J70. <5 1)' 1601100 <10 -~o 211
)s-6 c200 460 56r 419 <5 -5 26260 <10 -50 -25 10;>01.5 216550 JOO -0.2 -" 6J860' <5 -10 1)"500 <10 <50 -20.
)s-8 c200 <60 nr c200 <5 <~ 7000 16 <~o 2661 ~801 19.Jr H670 106. <0.2 -40 478401 7.6r <10 2870900 - 10 -50 22!
40-14 c200 <60 .,0 298 <~ -~ 2 J990 <10. -50 -25 116JO 6.0! 1~5670 6.)' -0.2 1091 116040: <~ <10 6Hoooi <10 <50 1161
40-17 clOO <60 12r 2680 <5
-------
-
Determination - Page 28
to be highly buffered and exhibited near-neutral pH values. The
trench samples yielded negative results for RCRA screening tests
for sulfide and ignitability. Additionally, organic and
inorganic analyses performed on the trench leachate samples
indicated that EP Toxicity and Toxicity Characteristic
Leachability Procedure (TCLP) test results would also be
negative for those samples. Table 7 presents the results of
RCRA analyses performed on trench leachate samples.
5.1.2 - Geology and Ground Water
Maxey Flats is located in the Appalachian Plateau, in the Knobs
physiographic region of northeast Kentucky. The MFDS lies in a
tectonically stable region of North America with few exposed
faults and relatively infrequent earthquakes. However, minor
damage from earthquakes has been reported in the region from
recent earthquakes, one of which occurred in 1988, having a
magnitude of 4.5 on the Richter Scale with an epicenter
approximately 25 miles southwest of the MFDS.
Figure 6 illustrates the rock units. exposed in the area
surrounding MFDS which consist of shale, siltstone, and
sandstone ranging in age from the Silurian to Mississippian (320
to 430 million years old). In the MFDS area, the rock units dip
25 feet/mile (0.3 degrees)~ regionally they dip to the east at
30 to 50 feet/mile.
The Nancy Member of the Borden Formation is exposed on the
hilltop at the MFDS and is 27 to 60 feet thick. . The unit is
mostly shale with two laterally extensive siltstone beds, the
Lower Marker Bed (LMB) and Upper Marker Bed (UMB). These beds
are 0.2 to 2.8 feet thick where encountered during drilling
operations at the MFDS.
Underlying the Nancy Member, the Farmers Member of the Borden
Formation is characterized as an interbedded siltstone and
shale, approximately 29 to 42 feet thick. Underlying the
Farmers Member is the four to seven feet thick shale of the
Henley Bed, 17 to 18 feet thick Sunbury Shale, and 21 feet thick
Bedford Shale.
Fractures are present in all rock units at the MFDS, with
fracture sets oriented, in descending order, northeast-
southwest, northwest-southeast, and north-south. The fracture
8et5 are generally within 20 degree8 of vertical. The weathered
shale of the Nancy Member is tne most highly fractured. Most
ground water available for sampling during the RI was obtained
from fractures of geologic units. Figure 7 identifies the
location of monitoring wells sampled for ground water.
-------
Determination - Page 29
TABLE 7
RESULTS OF RCRA ANALYSES FOR TRENCH LEACHATE
TRENCH SULFIDE IGNITABILITY
SUMP ~ SCREEN SCREEN
7-2 7.50 Neg Neg
7-9 7.83 Neg Neg
195-6 . 7.32 Neg Neg
195-7 7.33 Neg Neg
195-8 7.66 Neg Neg
26-2 7.80 Neg Neg
26-3 8.03 Neg Neg
27-5 5.07 Neg Neg
32-9 7.83 Neg Neg
32-9d 7.89 Neg Neg
32-E 8.49 Neg Neg
35-4 8.05 Neg Neg
35-6 8.24 Neg Neg
35-8 8.65 Neg Neg
40-14 7.57 Neg Neg
40-17 8.14 Neg . Neg
Neg) Negative results
d) Duplicate sample
Note: Organic and inorganic analyses performed on the trench leachate
samples indicated that EP Toxicity test results would be negative.
-------
FIGURE 6
Determination - Page 30
NW
-il 1OO
1050
2
O
1OOC
950
9OO
t * At.t.t HA IION • W*
EXPLANATION
COXHHIH INKIWMS
iO rC, I ml
100 *Ci ' ml
lino id i "'i
IUOOO Kl. /"•'
IUU UUU |>Ci / ml
1 OUOUOUDt, / ">l
• WONITODINC WfLtS SAMTLiO AND
ANALYZED FOR 1HIIIUM IN POHt
WATin
Mt 1M
HOIIIlOIIIAl JCAU
UAMIV flAfS
MAX IV Fl All SITi Hi/ft
EIASCU SJHVICtS INCORPOHH1I IJ
GEOLOGIC CROSS StCllON B U
WI1M INltHPRtllVt TRITIUM
CONTAMINATION 2ONI.S
UliUHl I"
-------
FIGURE 7
Determination - P.
LOCATION OF MOMTONING WELtS
SAMPLED f OR aitOUMDWATEM
-------
Determination - Page 32
The distinguishing feature of the Nancy Member, and perhaps that
of the site's geology, is the Lower Marker Bed of the Nancy
Member. The LMB is a thin siltstone layer that is generally
flat-lying (some local undulations of the bed are present,
however), fractured and weathered, and lies approximately 15 to
25 feet below ground surface. The LMB is the principal leachate
flow pathway at the MFDS and underlies or intersects the
majority of disposal trenches. Consequently, the LMB is a
highly contaminated geologic unit at the MFDS. Another
distinguishing characteristic of the LMB is that underlying
units are hydraulically connected to the LMB. However, rates
and quantities of flow to the underlying units are, most likely,
low.
It is estimated that the maximum total flow rate away from the
Restricted Area and through the LMB represents 70 percent of the
entire flow system at the MFDS. The volume of LMB exfiltration
to the hillslopes has been estimated at approximately 159
gallons per day, at a minimum. The total flow from the LMB and
lower lying beds has been estimated at 227 gallons per day.
Vertical migration between geological strata is limited by shale
layers of low permeability, which act as aquitards. On the west
side of the site, trench leachate migrates horizontally through
fractures of the Lower Marker Bed, which lies approximately 15
feet below ground surface in that area. On the east side of the
site, the 40 series trenches, which commonly bottom near the top
of the Farmers Member (approximately 40 feet below ground
surface), leach tritium and other contamination to the Farmers
Member. Because the MFDS is bounded on three sides by steep
slopes, the contaminated leachate migrating horizontally through
the fractured siltstone layers generally moves into the bottom
of the soil layer on these hillslopes. However, as evidenced by
the occurrence of seeps on the east hillside, not all leachate
migrates to the bottom of the soil layer on the hillslopes.
Hydrogeologic evaluations of the MFDS indicate that ground water
movement through the rock strata to the disposal trenches may be
negligible. Bowever, a potential pathway for ground water flow
into the trenches would be through the narrow neck at the north
side of the site where the MFDS trench area is connected to the
main portion of the Maxey plateau. Because of present water
. mounding at the site (i.e., there is a higher potentiometric
surface at the center of the site than at the edges), the
tendency is for water/leachate to migrate outwardly from the
site rather than into it. Furthermore, even if the trend were
-------
Determination - Page 33
reversed, the ground water migration into the trenches is
anticipated to be minimal for two reasons. First, the very
limited permeability of the various rock strata (except through
fractures) would preclude significant migration. Second, due to
the natural geological configuration of the MFDS plateau and the
narrow land bridge connecting the MFDS to the remainder of the
plateau, ground water flowing south toward the trenches would
very likely migrate and drain into the natural gullies to the
east and west of the connecting land bridge rather than migrate
the longer distance into the trenches. Further modeling,
monitoring, and data evaluation are planned to assess
hydrogeologic conditions at the MFDS.
Tritium is the predominant radionuclide detected in ground
water, as confirmed during the RI. Samples taken from
monitoring wells in the Lower Marker Bed had higher tritium
concentrations (up to 2,000,000 pCi/ml) than samples taken from
deeper geologic units, with the highest tritium concentrations
detected on the west side of the Restricted Area. Other
radionuclides detected include cobalt-60, carbon-14,
strontium-90, radium-226, uranium-233/234, uranium-235,
uranium-238, plutonium-238, and plutonium-239/240. These
tritium concentrations and the presence of other radionuclides
indicate that the contamination was caused by trench leachate.
Table 8 summarizes the results of radionuclide analyses on
ground water samples collected during the RI.
Non-radionuclide analyses in monitoring wells indicate the
presence of organics and inorganics such as benzene, toluene,
xylenes, arsenic, total phenolics and cyanide. The highest
concentrations of non-radionuclides were detected in wells
completed in the LMB on the west side of the Restricted Area,
which also had the highest radiological contamination. Tables 9
through 11 present the results of organic, inorganic and RCRA
analyses on ground water samples collected during the RI.
The LMB and the Farmers Member are the two principal geological
formations at the MFDS by which leachate migrates to the
hillslope8.
5. 1. 3 - Soils
Soil cover on the hillslopes in the MFDS area averages five feet
thick, but ranges from 0.5 to greater than 18 feet thick. The
soil types are generally an upper soil unit of clayey silt, and
a lower soil unit of silty clay.
-------
'ellpl In.
1I11L- ..b1L-
!!!!!!I!-1
111.12 U'O~'II
'11 -III 01'0)'11
111,1,)" '1'0)'"
111.14 01''''11
111'1' 01,'''11
111-" 11,"'11
.SI -14 ."",.
III'" O)"~'"
111"1 01,06'"
III-~" 01,'''11
....1 OIIlZlIl
...... 01' 10'11
UII!!i:...l
111-(" 04".'"
111-.'1 04110/"
III"" 0.".,11
III-'" 04'10,11
111-'" 04'U,1I
III -III. ..illl11
111.116 04,U,1I
:::: :::.. 04ill'"
..,U,II
III' ;~, 04,11,11
UI.l 0.,,.,11
...... "'15'"
Determination - Page 34
TABLE 8
..DIOIUC&.ID( COIIet.fla'IOils. ,. uou.n WAIIII
(c:oncenu.".. In pCl'.'.
"II ,... U! Sr .90 [0'60 u.:.ill ...u. u lU,Hc. u ll', u 1'8 I'u III "u /111/1411
.,00001., - 100000 .I~ 0.0) .'-0.02 0.' .,-0.' -0. I 0.0001.,. 0.0001 0.02~ -, 0.00) 0 OUOI" .I. LILlI u CJH., 0.0006 0, U. "U 0' U IIlI.' ., u uD'
-.,.U- "0 O. It .'-0.01 0.1 .,,0, I ca.' 0.0001"".100) D.10!. ."0.001 .0 01.108 u 00/4', '0.0009 O.lh -, D,OOY 0 UtJlO., 0 0000
-.,-.,- .'0 0,0' ."0." 0.1 .'-0,1 <10.1 0.0001"'1.8004 0.100 "'0.008 -0.0001 U 0010" 'U.OOIO 0.14 ., 0.01 U UO/l.'"u OUU.
...../. .- ..0 0.00"'-0.101 O.~ ."0.1 cO.I " .. ." .0 .0 ."
n..,. ,.. "0 o.n .'-0.11 -0.1 <10.1 0,08U."I.8001 O.OOh-, 0,000\ -0.0001 u .00(1\-, 0.000' 0.009 -,.u.oo/ u 00"', IJ UOU8
......,. 1- .'0 0.O'9-,-O.OO~ 0,0041"0.02 ..0.1 . .. .. 00 .. o.
.,.-,- '80 -,. n.. ..'-D.. ..0.1 "0.1 " .0 o. o. .. o.
.11 .'0 0.010.,.0.001 "0.1 -0. I . .. o. ." .. .0
1-',,)- ..0 0,011.,....., 0.' .'-0.' cO., O.OOOh,.O.OOO4 0.092 -"0.00\ -".0006 u,OOlv,/'D.OOO' O. ,. -, U.04 1.1 (uU ./ 1.1 UUI
.11 .'0 0.0' .,. 0.0' co. I ..0.1 . .. 0" 00 .. .0
.10 "0 0.011.'-0.'" ..0_' .0.' O.DII .'-0,00' 0.010 ./,0,0111 "O.ODOI 0.00\ .., d.OOI 'O.O(U U OU\ " u.au'
.11 "0 0."",-,.111 ..0.1 "0.1 0.41 ."1.12 0-0014-"0,000' O.OOOI., .tJ .0001 O.OOU.., o.ooo~ 0.0000)'" U .0001 'O.OUOI
'40000., "0000 .10 -u 004 0.4 .,. 0.' "0.1 .' ." o. 0: .. 0'>
..0000-, 1000. .,. ] 16 -,' 0.01 o.~ -,' 0.' ..0.1 0.000')-"0,0001 u.09/ ./.tJ.OO') -O.OUU.. 0 0:11'-, O. 000\ 0.049 ., 0.004 -O.U~I
1'8801-, 11000 "0 0 00\." 0.002 O. ~ .,. 0.' .0, I .. .0 00 ." .0 .,.
.,.., II -10 .0 OO~ '0.1 ca.' . .. .. .0 .. ..
"...-,. 'II -II ..a 00' ..0.1 ..0.1 . .. .. .. .. ..
"0./ 10 -.. -o..~ -0.1 cO, I " .. .0 .. .. ..
,.., ~ .,. ..0.00' ..a.' "0,1 " .. .. .. .. ..
1.0080-, .0000 -'0 O.U .,. 0.01 0.' .,. 0_' cO., 0.00044.1-0.00009 0.091 -"0.00\ ..0,000) 0,00''''./' 0.000\ 0.11 -/ 0.01 II.UUI/', U.OOOI
!IOOGCh,. ,- ..0 0, ID -I' 0.0' 0.. .,. 0.' ..0.1 0._'-"'.-' 0."4 -/.0.006 0.'" "'0.001 0.0041"'0,0001 0.10 ., 0,01 O.UUll., 1.1 0001
-'0 ..0 ..0.00\ -0.' cO. I " o. .. .0 .. o.
-'0 ..0 ..0.00' cO. I ..0.1 . .. .. .. .. .0
",e_,. '0 ..0 cO,OO' -0.' cO. I O..OM ./-1.011 0.008 "'0.001 0.0008-" 0.001»4 I».OO~"I'O.OOO' 0.001) "'0.000' . 0 00U4
.. ...,,11 .u.~CI; lft4Hpenoe"l ene' ,... pe' '0'"'' 1ft 'II. .."'''''' '.bIMI O' 8U88n ...8Uf(:.. 1800,elo't 00 e G...pl lite.. .....1. ".d . If't' 'U8 ,unc.nuell.., o' 1.0 ./. O.l pC I'.' ,"ulp.., W.'.
.. 0.,., i,u. .......
.) .. '.'.. .....1,... MI pe,to,.,. '0' ."... e'",. .....,. C.e.JI6 .... I..'.I~ U and .", Me..... "0" elf*8 .... I.... ,".n Q on p(t'.1
-------
TABLE 9
-,
OIGAIIC CME"ICAL CONCEITIATIOIS II GlOUNOWAtEI
(concentration. in ppb)
LOWEI MAIKEI lED
OIGAIIC ClERICAL Ell-) ESt-3d ESt-4 ESI-2 ESI-t9 ESI - '9d ESI-8
II az ..!.L at a2 I' U I' a2 .n- R' R2
Acetona <'0 <'0 <'0 <'0 c'O c'O c'O c'O c'O c'O c'O c'O
len..". 86 66 86 c5 9 18 25 65 96 84 c5 .5
to'ue". ., <5 9 cS c5 <5 cS cS. 6 c5 1 c5
I.pllt"".n. <'0 <'0 <'0 c'O cto ctO c'O tOJ ctO c10 c10 c10
Wlny'ch'orlde 76 4S 97 c'O c'O c'O ctO 29 40 J7 c10 c '0
Chi oro' or. <, <5 <5 24 2' <5 <5 <5 c5 c5 <5 c5
'.1 Dlch'oroetha... 6 <5 1 <5 cS 6 6 9 cS c5 c5 cS
1.2 Dlch'.roethene 12 12 15 <5 6 cS c5 5 8 1 c5 c5
1.2 Dlch'.roethane Sf 41 69 6 11 6 9 34 51 52 .5 c5
1 r' cMoroethene '00 9) 96 9 17 <5 1 32 6J 55 <5 c5
CM orolMnl8'" <, 9 " c' c' c' cS cS c5 <5 c5 c5
lOWEI MAIKEI lEO/
lOWEI lAIC' lOWEI IIAln UPPU UI.US 0"10 $IIAIf 0"'0 SHAlf
OIGAIIC CIIENICAL ESI-24 151-'2 ESI-" UI-2 UA-4
az IZ II R2 III 112 II U .1 U
AC8tone <'0 <10 <10 <'0 14J cll 200' 2200i c'O c'O
18ftlane c' c' c5 c5 c' <5 <, cS t2 12
'olue... <, c5 cS .S .5 II 5 <5 '2 1
'henol <10 <10 <10 .10 .10 c10 <10 '00 .10 290
earbon dlaul'lde .' .5 <' .5 <' .5 c' cS cS 8
'Inytchlorlde <'0 <'0
-------
Determination - Page 36
TABL,t:. l~ ..
IMO«GAMIC CHEMICAL CONCEMIIAIIOtS IH GlOUHDWAJEI
(concentr.tionl in ppb)
lOWER MARKER 'EO
I HOI'.HI CS ESI-01 ElI-05d ES I .04 ESI.Ol ESI-19 E51-19d E51-08 ( 5 I- 11,
., IZ ..IL ., 12 R1 Rl ., 12 ..!l. R1 R2 II 12
A' c200 c200 c200 4100j 469j 2110r 8S1j clOO <200 <200 1260; <200 <200 <200
Sb c60 c60 c60 c60 c60 <60 <60 c60 <60 <60 <60 <60 <60 '60
.1 57 44r 57 25J 29r 46 60r 66 67r 90r <10 <10 <10 '10
I. c200 c200 cZOO c200 c200 c200 <200 c200 c200 <200 <200 <200 <200 <200
I. c5 c5 c5 c5 c5 <5
-------
TABLE 10 (CONTINUED) Determination - Page 37
...'
I'~GANIC CHEMICAL CONCENIIAIIGNS IN 'IOUHDWAlfl
(concentr.tionl in ppb)
LOWE. KAIKEI If 0/
L". IAI" LOWEll NAIICY UPPEII f AItMEI S OH,O SHALE OHIO SHALE
II~"IICI 111.24 ESI-12 ESI-16 UI-2 UA-Io
II IZ ., It2 111 1t2 II 1t2 RI R2
AI 4670 2740 3960i 1390i 7001 2470i <200 2060i ~oj 1960i
Sb c60 c60 c60 <60 <60 <60 <60 <60 <60 -60
al c10 c10 c10 c10 c10 <10 16r <10 < 10 -10
I. c200 cZOO c200 c200 c200 c200 1140 ])80 7Z70 J770
I. cS cS cS
-------
Determination - Page 38
TABLE 11
RESULTS OF RCRA ANALYSES FOR GROUND WATER
SULFIDE IGNITABILITY
~ -ElL SCREEN SCREEN
ESI-2 8.13 Neg Neg
ESI-3 8.04 Neg Neg
ESI-3d 8.08 Neg Neg
ESI-4 7.61 Neg Neq
ESI-8 7.20 Neq Neq
ESI-12 8.00 Neg Neq
ESI-14 6.85 Neq Neg
ESI-16 NA NA NA
ESI-19 8.02 Neq Neg
ESI-24 7.26 Neg Neq
UA-4 6.77 Neq Neq
UB-2 7.25 Neg Neq
Neq) Negative Results
NA) Not Analyzed
d) Duplicate Sample
Note: Orqanic and inorqanic analyses performed on these samples indicated
that EP Toxicity test results would be negative.
-------
Determination - Page 39.
Figure 8 identifies the locations of soil samples obtained from
hand augers during the RI. In the soils on the three slopes
adjacent to the site, tritium is the predominant contaminant,
with the largest contaminated areas and highest levels of
tritium contamination on the upper part of the northwes~ side of
the site (north of the Western Series trenches). Tritium
concentrations ranged from non-detect to 560,000 pCi/ml. The
soil analyses, in conjunction with the ground water and trench
leachate analyses, indicate that tritium has migrated through
the fractured LMB from the trenches toward the west hillslope
and has subsequently migrated down-slope along the soil/rock
interface. Additionally, elevated tritium concentrations (50 to
420 pCi/ml) were observed near the center of the east slope,
below an outcrop of the fractured Farmers Member. See Figure
9. This tritium originated in the 40 Series trenches on the
east side of the site, which were excavated to near the top of
the upper Farmers Member. Other site-related radionuclides
detected in soils at the MFDS include cobalt-60 (0.3 pCi/gram)
and cesium-13? (0.1 - 0.8 pCi/gram). Previous testing along the
soil-rock interface by the Commonwealth indicated the presence
of additional radionuclides such as strontium-90, carbon-14, and
plutonium-238 and -239. Table 12 provides the concentration
ranges of radionuclides in RI soil samples.
Toluene was the most widely detected chemical contaminant at the
MFDS, ranging from 40 to 250 ppb. Other volatile organic
contaminants detected in soils include acetone and methylene
chloride in low concentrations. Pesticides, PCBs, and
semi-volatile contaminants were not detected in soils of the
MFDS study area, with the exception of one pesticide, Dieldrin,
which was detected in a food crop study area (See discussion
below). All soil samples displayed inorganic concentrations
within ranges considered normal for soils, with the exception of
Arsenic, which was detected at 60 to 106 ppm. Tables 13 and 14
provide the concentration ranges for organic and inorganic
analyses, respectively, performed on site soil samples during
the RI. As indicated in Tables 15 and 16, negative results were
reported for the RCRA parameters tested for soil and soil
water. Organic and inorganic analyses performed on these soil
samples indicate that EP toxicity and TCLP test results would
also be negative.
Samples collected in the food crop study area (See Figure 10 for
sample locations) indicate no site-related contamination in
these off-site locations. Dieldrin, a pesticide, was detected
in one .food crop sample but is 'related to farming activities
rather than the site.
-------
FIGURE 8
Determination - Page 40
• ROUND I SAMTlf POINTS
=- HOUMO I IHANStCl
WITH TRANSECT NUMUtfl
APPROXIMATE MFQS
PHOMHTV IOUNDAHV
HAND AUGCM SOIL SAMPt I
POINTS AND TRANSECT LOCATIONS
nuuHt •
-------
FIGURE 9
Determination - Page 41
\ /
// \ >
J ; /•• \;
EXPLANATION
MFOS Rf SIRICflD AM A
BOUNDARY
APPROXIMATE UfOSPROPERTY
•OWWAIIV CamOU*
SO pCJtnl lin.Mm
100 pCi/ml Tiiliulfl
M» pCi/ml liilnon
MOO pO/ml Ttilium
10,000 nCrfrol Inuum
t"\
in Ml Ml
1C All III HIT
MAKiV ILATSHIHtrOHT
MAXIV Fl AT« Sill HUH
g.ASCO SfHVICIS INCOWfOHAIl Cl
THI1IUM
CONCENTRATION IN MUIS1UR1 K(l»1
HAND AUGER SOIL SAMflti
HGIIRI 4 4
-------
Determination - Page 42
TABLE 12
CONCENTRATION RANGES OF RADIONUCLIDES IN SOIL
(concentrations in pCi/ml or pCi/gram)
Background Food Crop Hand Auger
Radionuclide Soila Study Area Soils
Tritium
-------
Determination - Page 43
TABLE 13"
CONCENTRATION RANGES OF ORGANIC CHEMICALS IN SOIL SAMPLES
(concentrations in ppb)
Chemical
Background
Soil a
Food Crop
Study Area
Hand Auger
Soils
Methylene
Chloride
Chloroform
<5 <5 <5-6
<5 <5 <5
5j-35 7-180 <5~250b
<10 <10 <10-36j
<10 <10 <10
<330 <330 <330
<16 <16-290 <16
<330 <330 <330
<330 <330 <330
<330 <330 <330
Toluene
Acetone
2-Butanone
Di-n-octyl
phthalate
Dieldrin
Phenanthrene
Fluoranthene
pyrene
a)
j)
Daniel Boone National Forest
Bstimated value because of exceeding a data validation
criterion, or below detection limit due to laboratory
sample dilution
Bstimated value due to the detector's response being
out.ide of the detector's linear range
b)
-------
Determination - Page 44
TABLE 14
CONCENTRATION RANGES OF INORGANIC CHEMICALS IN SOIL SAMPLES
(concentrations in ppm)
Background Food Crop Hand Auger
Analvte Soila Study Area Soils
Al 8540-11100 7090-10100 2980-10900
Sb <12 <12 ,<12
As <2-14.6j <2-27.1r 6.7J-106.0j
Ba 45J-64 <40-95 <40-163
Be <1 <1 <1-8.8
Cd <1 <1 <1
Ca <1000 <1000-1330 <1000-2180.
Cr 15.0-18.4 10.5-16.5 6.4-18.8J
Co 11.3-14.6 <10-26.2 <10-25.5
Cu 9.3-15.7 <5-61. 2 <5-53.7
Fe 21400-28500j 15200-31400 16000-95200
Pb <1-19.8 12.7-33~2 2.4-39.6
Mg 2770~-3030 <1000 <;1000~4260
Mn 98J-250J 371J-850j, 8J-538J
Hg <0.04. <0.04-0.06Jn <0.04-0.20jn
Ni 28-44J <8-22 <8-63J
K <1000-1890j <1000-1280 <1000-2160
Se <1 <1 <1-4.2J
Aq <2 <2 <2
Na <1000 <1000 <1000-1880
TI <2-5.2j <2 <2-3.4
V 21-28J 24-72 <10-276
Zn 49-67 <4-90 6-298
Cyanide <2 <2 <2
Phenolics <2 <2 <2
a)
j)
Daniel Boone National Forest
Estimated value because of exceeding a data validation
criterion, or below detection limit due to laboratory
sample dilution
Estimated value and tentative identification
jn)
-------
Determination - Page 45
TABLE 15
RESULTS OF RCRA ANALYSES FOR HAND AUGER SOIL SAMPLES (ROUND 2\
ACID REACTIVITY BASE WATER
LOCATION pB SULFIDE IGNITABILITY BCL / H2S04 REACTIVITY REACTIVITY
03T-32 3.9 Neq Neq Neq / Neg Neq Neq
05-10 4.6 Neq Neq Neq / Neg Neq Neq
05A-35 4.0 Neq Neg Neq / Neq Neq Neq
06-10 5.5 Neq Neq Neq / Neg Neq Neq
06-10d 5.7 Neq Neq Neq / Neq Neq Neq
06-20 6.2 Neq Neq Neq / Neq Neq Neq
11A-00 4.4 Neq Neq Neq / Neq Neq Neq
12A-30 4.4 Neq Neq Neq / Neq Neq Neq
12A-30 4.5 Neq Neg Neg / Neg Neq Neq
13A-38 4.2 Neq Neq Neq / Neg Neq Neq
17-10 5.2 Neq Neg Neq / Neg Neq Neq
17-10d 4.5 Neq Neq Neq / Neq Neq Neq
18A-00 4.6 Neq Neg Neq / Neg Neq Neq
43A-I0 4.6 Neq Neq Neq / Neg Neq Neq
48-30 5.4 Neq Neq Neq / Neg Neq Neq
50A-05 5.5 Neq Neq Neq / Neg Neq Neq
58A-05 3.9 Neq Neg Neq / Neg Neq Neq
58A-15 6.8 Neq Neg Neg / Neg Neq Neq
Neg - Neqative test results
d - Duplicate sample
Note:
Organic and inorqanic analyses performed on these samples
indicated that EP Toxicity test results would be neqative.
-------
Determination - Page 46
TABLE 16
RESULTS OF RCRA ANALYSES FOR SOIL WATER
Date
SamDled -B1L Sulfide Screen Iqnitabilitv Screen
WP-1 03/07/88 7.39 Neg Neg
WP-1 d 03/07/88 7.44 Neg Neg
WP-1 04/19/88 6.40 Neg Neg
WP-1 d 04/19/88 6.30 Neg Neg
I
d) Duplicate sample
Neg) Negative results
Note: Organic and Inorganic analyses performed on these samples indicated
that EP Toxicity test results would be negative.
-------
FIGURE 10
Determination - Page 47
__
C-38S nESTRiCTE
MAXEV FLATS RlREPORT
MAKE Y FLATS SITE RI/FS
EBASCO SERVICES INCORPORATED
Q Foot! Crop Study Ait* Soil Simple location!
Approximate MFDS Pi open y Bouiutiry
A Btck ground Soil Sample Locutions
LOCATION OF BACKGROUND AND
FOOD CROP STUDY AREA
SOIL SAMPLE
-------
Determination - Page 48
5.1.4 -Surface Water and Sediments
Surface water and sediment investigations during the RI involved
the collection and analyses of samples from surface water runoff
leaving the Restricted Area (which exits through three water
control structures located at the periphery of the Restricted
Area) and off-site creeks which receive runoff from the MFDS as
well as from off-site sources. Figure 11 illustrates the
locations of surface water and sediment sample collection during
the RI.
Tritium (10 to 60 pCi/ml) and Radium-226 (0.26 pCi/gram [Rock
Lick Creek] and 0.29 pCi/gram [Drip Springs Bollow]) were the
only radionuclides detected in the surface water samples during
the RI. Concentrations of tritium were highest at the water
control structures adjacent to the Restricted Area and decreased
with distance away from the Restricted Area. The principal
sources of tritium entering these structures are contaminated
liquids that have migrated from the trenches to the hillslopes
through fractured bedrock and atmospheric releases of tritium
from the trenches. The concentration ranges of radionuclides in
surface water samples are presented in Table 17.
The Commonwealth of Kentucky has detected Strontium-90 in
surface water in the East Main Drainage Channel. The
Commonwealth has also detected Strontium-90 in the east pond, at
the east pond outlet, and in the south drainage area.
Additionally, the Commonwealth has detected tritium
concentrations in various site drains in excess of 1000 pCi/ml.
Analytical results from the RI indicate low concentrations
(ranging from 5 ppb to 98 ppb) of chemical constituents in
surface water. Chemical contaminants detected in surface water
samples were limited to acetone, 2-butanone, chloroform,
toluene, bis(2-ethylhexyl)phthalate, and hexachlorobenzene.
Concentration ranges of organic and inorganic chemicals are
presented in Tables 18 and 19, respectively. .
" . ~-
In conjuaction with the surface water sampling program during
the RI, sediment samples were collected at the same locations
(See Figure 11). Sediment sample analyses indicated tritium in
concentrations ranging from 10 to 70 pCi/ml. Tritium
concentrations were greater at the water control structures
adjacent to the Restricted Area than at the more distant stream
sampling stations. Other radionuclide concentrations in
sediment moisture were within the range of background
concentrations. (See Table 20 for concentration ranges of
radionuclides in stream sediment samples.)
-------
FIGURE 11
Determination - Page 49
N
\
/
r
N
EXPLANATION
A Sr/f*m Sampling Sltlion
— — Approximate MFltS Property BiHintlaiy
iirnfH SAUflINK STA HOMS AHC I OCAUHAI WtSI
mt »i ti r 4 *• T it«*i*n fttttftt ti'F t O
MAXEV FLATS Rl REPORT
MAXEY FLATS SITE RI/FS |
\
EBASCO SERVICES INCORPORATED
LOCATION OF SURFACE WATER
AND SEDIMENT SAMPLING STATIONS
-------
Determination - Page 50
TABLE 17
CONCENTRATION RANGES OF RADIONUCLIDES IN SURFACE WATER
(concentrations in pCi/ml)
Backqrounda Downstream Site Area MFDS
Surface Water of Site Area Streams Ponds .and Weir
Tritium <10-40b <10-31b <10-30 <10-60
K-40 <1.0 <1.0 <1.0 <1.0
Cs-137 <0.1 <0.1 <0.1 <0.1
Ra-226 <0.1 <0.1-0.29 <0.1 <0.1
Th-232 <0.2 <0.2 <0.2 <0.2
U-238 <2.0 <2.0 <2.0 <2.0
Co-60 <0.1 <0.1 <0.1 <0.1
\) Daniel Boone National Forest and Stream Sampling Station A (upstream of
~ite Area). .
b) High value suspect, see Appendix E, Section 4.1 of MFDS RI Report for
discussion.
"."-
- r-.-'
-------
Determination - Page 51
TABLE 18
CONCENTRATION RANGES OF ORGANIC CHEMICALS IN SURFACE WATER
(concentrations in ppb)
Organic Backgrounda Downstream Site Area MFDS
Chemical Surface Water of Site Area Streams Ponds and Weir
Acetone <10 <10 <10-68 <10-14
Toluene <5-9 <5-5 <5 <5-42
Chloroform <5 <5 <5-5 <5
2-Butanone <10 <10-36j <10 <10
Bis(2-ethyl
hexyl)-phthalate <10 <10 <10 <10-98
Hexachloro- <10-29j
Benzene <10 <10 <10
Heptachlor <0.05 <0.05 <0.05 <0.05-0.09
Endosulfan 1 <0.05 <0.05 <0.05-0.08 <0.05
a) Daniel Boone National Forest and Stre~ Sampling Station A
(upstream of Site Area)
j) Estimated value because of exceeding a data validation criteria, or
below detection limit due to laboratory sample dilution.
4",-.
-------
.'
Determination - Page 52
TABLE 19
CONCENTRATION RANGES OF INORGANIC CHEMICALS IN SURFACE WATER
(concentrations in ppb)
Backgrounda Downstream Site Area MFDS
Analvte Surface Water of Site Area Streams Ponds and Weir
Al <200 <200-430 <200-880 <200-1820
Sb <60 <60 <60 <60
As <10 <10 <10 <10
Ba <200 <200 <200 <200
Be <5 <5 <5 <5
Cd <5 <5 <5 <5-5
Ca <5000-9540 11700-24400 5390-26200 <5000-40500
Cr <10 <10 <10 <10
Co <50 <50 <50 <50
Cu <25 <25 <25 <25
Fe <100-660 <100-2490 360-560 <100-1090
Pb <5 <5 <5 <5
Mg <5000 <5000-10200 <5000-5260 <5000
Mn 88-341j <15-961J <15-310 <15-172
Hg <0.2 <0.2 <0.2 <0.2
Ni <40 <40 <40 <40
. <5000 <5000-7450 <5000 <5000
.
.;)e <5 <5 <5 <5
Ag <10 <10 <10 <10
Na <5000 <5000-6920 <5000 <5000
TI <10 <10 <10 <10
V <50 <50 <50 <50
Zn <20-85 <20-43 <20-33 <20-22
Cyanide <10 <10 <10 <10
Phenolics <10 <10 <10 <10
a) Daniel Boone National Forest and Stream Sampling Station A
(upstream of Site Area)
. ." . ~..
....' " : ".
j) Estimated."a1ue because of exceeding a data validation criterion,
or below detection limit due to laboratory sample dilution.
-------
Determination - Page 53
TABLE 20
CONCENTRATION RANGES OF RADIONUCLIDES CHEMICALS IN STREAM SEDIMENTS
(concentrations in pCi/ml or pCi/g)
Backgrounda Downstream Site Area MFDS
Radionuclide Sediments of Site Area Streams Ponds and Weir
Tritium <10 <10 <10-20 <10-70
K-40 8.0-16.0 12.0-30.0 17.0-22.0 12.0-21.0
Cs-137 <0.1-1. 30 <0.1-0.10 <0.1 <0.1-0.40
Ra-226 0.90-2.50 1. 50-2.40 1.70-3.70 0.60-1.10
Th-232 0.80-1.20 0.80-1.40 0.80-1.20 1.00-1. 30
U-238 <2.0 <2.0 <2.0 <2.0
Co-60 <0.1 <0.1 <0.1 <0.1
~) Daniel Boone National Forest and Stream Sampling Station A
(upstream of Site Area)
".0-.
.. '. .. . .
-------
Determination - Page 54
Volatile organic chemicals (acetone, 2-butanone, methylene
chloride, and toluene) detected in sediment samples ranged from
5 ppb to 170 ppb. Semi-volatile organic chemical constituents
(phthalate esters, phenol, phenanthrene, fluoranthene, and
pyrene) ranged from 5 ppb to 1800 ppb. The highest
concentration detected was phthalate esters. Phthalate esters
were only detected in samples associated with surface water
runoff from the Restricted Area and the probable source of the
phthalate esters is the PVC used to cover the trenches. (See
Tables 21 and 22 for concentration ranges of organics and
inorganics, respectively, in stream sediment samples.)
5 . 1. 5 - Air
Although an air quality investigation was not performed during
the Remedial Investigation of the MFDS, atmospheric data is
available for the site from 1983 to present. For the years 1983
to 1987, the average gross alpha, gamma, and beta concentrations
measured at the air monitoring stations around the perimeter of
the Restricted Area were three to five times lower than the
maximum concentration permitted by Commonwealth regulations
outside the Restricted Area for individual radionuclides. The
average tritium activity measu5ed at the air monitoring stations
ranged from 240 to 3,090 pCi/m during the years 1983 to 1986,
and averaged 275 pCi/m in 1987. For comparative purposes,
the average tritium activity for 1987 is less than 0.2 ~ercent
of the maximum permissible concentration (200,000 pCi/m ) for
areas outside the Restricted Area. The highest average airborne
tritium concent5ation measured at a single location during 1987
was 1,260 pCilm , 0.6 percent of the average annual maximum
permissible concentration.
The primary source of airborne radiation prior to 1987 was the
evaporator system. (The site evaporator ceased operation at the
MFDS in 1986). The trend of airborne tritium concentrations has
closely followed the release of tritium by the site's evaporator
system..Tritium concentrations measured at the air monitoring
stations.)oarkedly decreased during 1983 and 1987 when the
evaporat~r.was not operating, and again in 1986 when the
evaporator was operating at lower capacities. Other potential
sources of airborne radiation are tritium transpired by trees,
diffusion of tritium vapor directly through the trench cap, and
the ascension of tritium-bearing gases escaping from trench
sumps.
-------
Determination - Page 55
TABLE 21
CONCENTRATION RANGES OF ORGANIC CHEMICALS IN STREAM SEDIMENTS
(concentrations in ppb)
Organic Backgrounda Downstream Site Area MFDS
Chemical Sediments of Site Area Streams Ponds and Weir
Methylene
Chloride <5 <5-10 <5 <5
Chloroform <5 <5 <5-10j <5
Toluene <5-75 <5-10 <5-5 <5
Acetone <10-72 <10-170 <10-20 <10
2-Butanone <10 <10-31 <10 <10
Di-n-octyl
phthalate <330 <330 <330 <330-1800
Dieldrin <16 <16 <16 <16
'henanthrene <330 <330 <330 <330-510
Fluoranthene <330 <330 <330 <330-410
pyrene <330 <330 <330 <330-380j
a) Daniel Boone National Forest and Stream Sampling Station A
(upstream of Site Area)
j) Estimated value because of exceeding a data validation criterion,
or below detection limit due to laboratory sample dilution.
.. .
-------
Determination - page 56
TABLE 22
CONCENTRATION RANGES OF INORGANIC CHEMICALS IN STREAM SEDIMENTS
(concentrations in ppm)
Backgrounda. Downstream Site Area MFDS
Analvte Sediments of Site Area Streams Ponds and Weir
Al 4800-8140 5820-8390 3750-8230 8000-11400
Sb c;:12 c;:12 <12 <12-13
As 13.3J-38.9 10.8J-59.3 14.2-38.0j <2-39.0
Ba <40-96 <40-63 43-83 <40-230
Be <1-1.5 1.3-2.6 <1-1.8 <1
Cd <1 <1 <1 <1
Ca <1000 <1000-18200 1250-30800 <1000-39900
Cr 14.3J-30.0 16.4-30.7 9.5-24.1 17.2-39.6
Co <10-59.2 21.4-40 10.5-26.9. <10-65.0.
Cu 8.6-27.3 23.2-54.9 23.2-46.7J 8.5-41.0J
Fe 4300-73200 36600-71300 22300-65400 22200-70700
Pb 19.4-42.1 9.8-30.7 21.2-23.9 <1-46.6
Mg <1000 <1000-2310 <1000-5070 1240-3940
Mn 261-682 295J-999 330-784J 92J-3530.
Hg <0.04 <0.04~0.01jn <0.04 <0.04-0.07Jn
Ni 16-42.0 52J-86J, 31-74j, 14-48J
<1000-1570 <1000-1950J <1000-1220J <1000-1500j
.)e <1 <1 <1 <1
Ag <2 <2 <2 <2
Na <1000 <1000-1390 <1000 <1000-1490
Tl <2 <2 <2 c;:2
V 28-76 62-109, 39-81j, 28J-66
Zn 55J-163j 177-297J <4-236J 40-123j
Cyanide <2 <2 <2 <2
Phenolics <2 <2 <2 <2
a) Daniel Boone National Forest and Stream Sampling Station
(upstream of S~te ..Area)
j) Estimated .alue because of exceeding a data validation criterion,
or below detection limit due to laboratory sample dilution.
jn) Estimated value and tentative identification.
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Determination - Page 57
SECTION 6.0' - SUMMARY OF SITE RISKS
As part of the RIfFS, an assessment of site risks was performed
by the Maxey Flats Steering Committee (Committee) using existing
site data and information gathered during the Remedial
Investigation. The Committee's Appendix D to the Feasibility
Study Report, and EPA's Addendum Report to the FS Report, may be
consulted for a more in-depth explanation of both the process
and results of the risk assessment for the Maxey Flats Disposal
Site. The dose estimates presented in this section are median
doses, unless otherwise noted. Additionally, the assumptions
employed in the calculation of site risks and resultant dose
estimates, provided in this section, are derived from the
Committee's final, April 1991 risk assessment, unless otherwise
noted.
The risk assessment identified the contaminant sources and
exposure pathways which pose the greatest potential threat to
human health and the environment and then evaluated the baseline
risks associated with a No Action alternative; i.e., a scenario
which assumed that the site would be abandoned. The risk
assessment assumed exposure scenarios that involved (1) the
degradation of the existing soil cap and the subsequent leaching
and transport of radionuclides offsite, and (2) individuals
trespassing and establishing residence at the site.
Potential contamination sources at the MFDS were determined to
include trench material, leachate, site structures, above-ground
tanks, ground surfaces, ground water, and soil. Potential
routes of exposure to contaminants, called exposure pathways,
were developed based on both the current site conditions and
future, potential pathways typically examined in a public health
evaluation. For the MFDS, two sets of potential pathways were
evaluated - intruder (on-site) pathways and non-intruder
(off-site) pathways. For the intruder scenario, it was assumed
that the site would be abandoned and an individual would occupy
an area of the site which is currently known as the Restricted
Area. T~.. non-intruder scenario, like the intruder pathways,
assumed.the'site would be abandoned, but involved pathways
(primarily off-site pathways) other than those associated with
occupying the site.
. Of the contaminants identified at the MFDS, two sets of
contaminants representing the greatest potential for impacting
human health, called indicator contaminants, were developed.
Table 23 identifies the two gr6ups of indicator contaminants
selected for the Maxey Flats Disposal Site, radionuclide and
non-radionuclide indicators.
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Determination - Page 58
TABLE 23
INDICATOR CONTAMINANTS
Radionuclides
Non-Radionuclides
Hydrogen-3 (Tritium)
Carbon-14
Arsenic
Benzene
Cobalt-60
Bis(2-Ethylhexyl) Phthalate
Strontium-90
Chlorobenzene
Technetium-99
Chloroform
Iodine-129
1,2-Dichloroethane
Cesium-137
Lead
Radium-226
Nickel
Thorium-232
Toluene
Plutonium-238
Trichloroethylene
Vinyl Chloride
Plutonium-239
Americium-241
.-
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Determination - Page 59
6.1
Off-Site Exposure Scenario
The pathways evaluated for the off-site exposure scenario are
listed in Table 24, and described below. In order to evaluate
the potential off-site exposure scenario, it was assumed that
the site was abandoned and no measures are in place to control
or mitigate site releases. Approximately 10% of rainwater was
assumed to penetrate deep into the trenches and leach
radionuclides from the waste. The contaminated rainwater was
assumed to percolate down into the strata underlying the
trenches and migrate laterally beneath the trenches to the MFDS
hillslopes. From here, the contaminated water was assumed to
partially evaporate and partially to be transported down the
hillslopes to the valley below. As a result of
evapotranspiration, tritiated water becomes airborne and is
transported off-site to receptor locations.
6.1.1 - Well Water Pathway
The off-site well water pathway includes the following
assumptions:
. A drinking water well in the alluvium becomes contaminated;
leachate migrates in ground water from the trenches through the
Lower Marker Bed (LMB), lower Nancy and Farmers Members to the
hillslope; migration down the hillslope is via surface water
runoff in washes; dilution by surface runoff water,
evapotranspiration losses on the hillslope, infiltration into
the alluvium at the bottom of the hillslope, and dilution in the
alluvial ground water by additional recharge and upstream ground
water occur.
. The MFDS and surrounding area are divided into eight
sub-basin drainage areas, which carry different proportions of
runoff and contaminants and are analyzed individually for
contributions to alluvial ground water in the stream valleys.
. Individuals use a well in the alluvium for drinking water
over a lifetime and consume two liters per day.
. No contaminants migrate via ground water through the
colluvium, soil, or bedrock into the alluvial aquifer.
. Radioactive decay reduces radionuclide concentrations over
the estimated travel time for the pathway.
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Determination - Page 60
.
TABLE 24
OFF-SITE (NON-INTRUDER) PATHWAYS
. Well Water Pathway -- involves the movement of contaminants
in ground water to the hillsides adjacent to the site and
into the surface water system moving down the hillsides.
At the bottom of the hillsides, the contaminated runoff
recharges the alluvium (soils). A well is excavated in the
contaminated alluvium and a family uses the well as a
source of drinking water.
. Surface Water Pathway -- in this pathway, contaminants move
off-site in ground water and enter the surface water
system. The stream water is then used as a drinking water
and irrigation source for beef and milk cows and their
forage. Humans then ingest the animal products.
. Soil Erosion Pathway -- this pathway actually is a
combination of pathways. It involves the resuspension in
air of soil particles contaminated with radionuclides and
the washing of soil into the surface water. It is assumed
that the trenches overflow with contaminated liquids.
Dry contaminated soil is then suspended in air and carried
to a person and inhaled or washed away in runoff. Also,
crops are grown in the alluvium contaminated by surface
runoff. A person ingests contaminated farm products and is
exposed to external radiation.
. Sediment Pathway -- involves the movement of contaminants
in ground water to the hillsides adjacent to the site and
into the surface water system (streams). As the
contaminated surface water moves through the stream bed,
some of the contaminants adhere to the soils in the stream
bed. Through the course of play in the stream beds, a
child ingests the contaminated soils.
. Deer Pathway -- Contaminated water moves through the ground
water--&ystem to the hillsides adjacent to the site. Upon
reaching the hillside, the contamination is incorporated
into plants. The contaminated plants are then eaten by
deer foraging on the hillslopes. Also, the deer drink
contaminated water from the streams. The contaminants are
then incorporated into the meat of the deer. A hunter
kills the deer and ingests the meat.
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Determination - Page 61
TABLE 24 (Continued)
OFF-SITE (NON-INTRUDER) PATHWAYS
. Evapotranspiration Pathway -- this pathway involves the
uptake of contaminated liquid into plants; the liquids are
released from the plants to the environment. Tritium is
the only contaminant to move by this pathway. Once released
to the air, the tritium could be incorporated into food and
drinking water sources or directly inhaled by a human.
. Trench Sump Pathway -- This pathway involves the escape of
tritiated water from trenches via trench sumps and cracks
in the trench cap. A person then inhales the contaminated
air.
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Determination - Page 62
. Radionuclides and other contaminants are subject to
retardation by sorption eff.ects'.
Figure 12 illustrates the projected extent of potentially
contaminated alluvium, under a No Action alternative, used in
evaluating exposures associated with the well water pathway.
6.1.2 - Surface Water Pathway
This pathway begins in the same manner as the well water
pathway~ that is, contaminated runoff travels down the
hillslope. However, unlike the well water pathway, where the
flow is divided into eight regions, all the radioactivity is
assumed to be deposited into a creek, and the creek water is
used as a source of drinking water for livestock. In addition,
grass in the vicinity of the creek is ingested by the
livestock. Humans then ingest the contaminated milk and beef.
6.1.3 - Erosion Pathway
Another pathway included in the off-site exposure scenario is
the erosion pathway. The erosion pathway assumed that, without
erosion controls, surface and hillslope soil will be transported
to the alluvial valley. The analysis is based on the assumption
that no steps are taken to prevent the "bathtub" effect or to
protect the overlying soil from erosion. As a result of the
"bathtub" effect, leachate is assumed to rise up periodically,
saturate the overlying soil, and overflow the trenches. The
overlying soil thereby becomes contaminated and, when eroded
down to the alluvial valley, becomes a source of exposure to
individuals living in the valley.
The erosion pathway actually consists of a subset of pathways
which include the following: (1) direct radiation from living on
contaminated alluvium, (2) the ingestion of contaminated surface
water, (3) the ingestion of vegetables grown in contaminated
alluvium~ and (4) the ingestion of beef and milk obtained from
cattle anQ milk cows raised on water obtained from the creek and
fodder f~om:'the contaminated alluvial plain.
The drinking water pathway of the erosion pathway is based on
the assumption that an individual obtains all his drinking water
. from a local creek. Doses from the ingestion of vegetables are
based on the assumption that all vegetables are obtained from
gardens located on the contaminated alluvium. Similarly, milk
and beef doses are based on the assumption that the cattle and
cows obtain all their drinking water from the creek and fodder
-------
FIGURE 12
Determinati
(?) ASSESSMENT REGION (8 HIGIONS)
UNCONTAMINATED ALLUVIUM
[ j ASSESSMENT REGION RUNOFF AREA
Wll t WAltH PATHWAY ANALYSIS
Ili.iiHI n 3
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Determination - Page 64
from grass growing in the contaminated alluvium. The doses also
include direct radiation from continual exposure from living on
contaminated alluvium. These doses were based on the assumption
that the contamination is an effective infinite plane, with no
credit taken for shielding. -
The exposures associated with the erosion pathways were
performed for a range of time periods that reflect a decaying
source term and a changing erosion rate. The results of the
analyses for the upperbound estimate for the erosion pathway are
presented in Table 25. EPA believes that the upperbound
estimates are the appropriate values associated with the erosion
pathway due to the number of uncertainties in the erosion
pathway analysis. See Section 6.3 - Risk Uncertainties, for a
discussion of risk assessment uncertainties.
6.1.4 - Sediment Pathway
Another off-site pathway evaluated in the MFDS baseline risk
assessment was that of a child ingesting contaminated
sediments. Contaminants travel to the hil1slopes and into the
surface water system. As the contaminated surface water moves
over the stream beds, some of the contaminants adhere to the
sediments of the stream bed. Then, through the course of play
in the stream beds, a child ingests 0.7 grams of contaminated
sediments per day. It was assumed that the sediments are
approximately 50% water, which contains tritium at the same
concentration as the surface water.
6.1.5 - Deer Pathway
This pathway involves the migration of contaminants to the
hillslopes. Upon reaching the hillslopes, the contamination is
incorporated into plants. Approximately 150 kilograms/year of
contaminated plants are then eaten by deer foraging on the
hillslopes. Also, the deer drinks 3650 liters/year of
contaminated water from the streams. The contaminants are then
incorporate~ into the meat of the deer. A hunter kills the deer
and inge.8.ta..5 kilograms of deer meat per year.
6.1.6 - Evapotranspiration Pathway
This pathway involves the uptake of contaminated liquids into
plants. Through the process of evapotranspiration, which is the
release of water vapor from the plants to the atmosphere, .
tritium is released to the air'and incorporated into food and
drinking water sources, or directly inhaled by a human. Tritium
is the only contaminant to move by this pathway.
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Determination - Page 65
PATHWAY
External Exposure
Drinking Water
Vegetables
Milk
Meat
. ~..:. -. '".
Table 25
EROSION PATHWAYS
DOSE CMREM!YEARI
160
440
11
1.4
1.9
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.
Determination - Page 66
6.1.7 - Trench Sump Pathway
This pathway involves the escape of tritiated water from
trenches via trench sumps and cracks in the trench cap. A
person then inhales the contaminated air. Tritium is the only
contaminant to move by this pathway.
6.1.8 - Conclusions of the Off-Site Exposure Scenario
The results of the risk assessment revealed that, for off-site
exposure pathways, tritium is the critical radionuclide. The
well water pathway is, by far, the dominant off-site pathway.
If no action is taken at the site, the total dose equivalent
from all indicators from all combined off-site pathways to
individuals would be 75 mrem per year for the average case,
almost half of which is attributable to tritium. The upper
bound estimate of exposure from such a scenario would total 4300
mrem per year. For each vear of exposure under a No Action
alternative, it is esti~ated that the lifetime risk of fatal
cancer wo~ld be 3 x 10- for the average case (75 mrem) and
1.7 x 10- for the uPierbound casg (4300 mrem). (EPA's target
risk range is 1 x 10- to 1 x 10- whici equates to one
additional cancer in 10,000 for61 x 10- and one additional
cancer in 1,000,000 for 1 x 10- .)
The lifetime risk of cancer from prolonaed exposure (many years
of 3xposure) from off-site path,ays would be approximately 1 x
10- (average case) and 6 x 10- (upperbound case). The
well water pathway contributes the single highest dose among
pathways, with soil erosion contributing almost all of the
remaining dose. Both the average and upper bound estimates of
off-site exposure exceed the MFDS remediation goal of 2S mrem
per year for the entire site.
During the 70-year timeframe (the period of time typically used
in evaluating risks at Superfund sites) for a No Action
alternat1ve, tritium and strontium-90 would exceed drinking
water l~ts in water extracted from wells located at the base
of the ~l~~lopes and the 4 mrem/yr Maximum Concentration Limit
for beta 'activity would be exceeded.
OVer the SOO-year time frame (which is a more lengthy period of
time than typically used at Superfund sites, but necessary due
to the presence of long-lived radionuclides at the MFDS),
tritium, strontium-90, and radium-226 would'exceed the drinking
water limits in water extracted from wells located at the base
of the hill~lopes during the initial part of the SOO-year
timeframe, before tritium and strontium-90 have decayed away.
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Determination - Page 67
6.2
On-Site Exposure Scenarios
Table 26 lists the on-site (intruder) pathways evaluated in the
MFDS baseline risk assessment, as described below. Evaluation
of the on-site exposure scenarios involved the assumption that
the site is abandoned and no institutional controls are in place
to prevent site access.
For the intruder scenarios, which consist of a number of
exposure pathways, a broad range of potential on-site exposures
were evaluated in order to gain insight into the full range of
potential impacts of the site and how those impacts may change
with time.
It is unlikely that the Intruder-Discovery, Intruder-
Construction, and Intruder-Agriculture scenarios could occur
today or in the immediate future; however, these scenarios were
included in the risk assessment to characterize fully the range
of potential exposures that could be associated with the site.
As time passes, these scenarios would become more likely.
6.2.1 - Intruder-Trespasser Scenario
Under the Intruder-Trespasser Scenario, a trespasser who
occasionally gains access to the site would be exposed to direct
external radiation and perhaps the inhalation of radioactive
particulates that may become airborne through suspension
processes. In addition, it is likely that the trespasser would
also be exposed to airborne tritiated water vapor due to the
evaporation of leachate.
6.2.2 - Intruder-Discovery Scenario
This pathway involves the assumption that no controls exist for
the site and an intruder inadvertently occupies the disposal
site and begins construction activities. The intruder contacts
solid remains of waste or barriers, realizes that something is
wrong, ~. .c;eases construction activities. Human exposure to
radiati~"is assumed to result for a short time from external
exposure"""to -the contaminated soils and inhalation of
contaminated air.
. 6.2.3 - Intruder-Construction Scenario
For the Intruder-Construction scenario, it is assumed that, in
the scenario described for the'Intruder-Discovery above, the
construction worker continues construction activities. In the
Intruder-Construction scenario, the builder is assumed to be
exposed from the following pathways:
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Determination - Page 68
TABLE 26
ON-SITE (INTRUDER) PATHWAYS
. Intruder-Trespasser Scenario: This scenario involves the
assumption that no controls exist for the site and a
trespasser occasionally gains access to the site.
. Intruder-Discovery Scenario -- This scenario assumes that
no controls exist for the site and an intruder
inadvertently occupies the site and begins construction
activities. The intruder contacts solid remains of waste
or barriers, realizes that something is wrong, and ceases
construction activities. Human exposure would occur
through the external exposure to contaminated soil pathway
and through the inhalation of contaminated air pathway.
. Intruder-Construction Scenario: This scenario assumes
that, in the scenario described for the intruder-Discovery
Scenario above, the construction worker continues
construction activities. Construction activities
penetrate and expose the waste. Human exposure would occur
through the external exposure to contaminated soil pathway
and through the inhalation of contaminated air pathway.
. Intruder-Agricultural Scenario -- This scenario involves
the assumption that no controls exist for the site and an
inadvertent intruder occupies the site. After some
construction activities, the intruder (site resident)
begins agricultural activities. It is assumed that some
percent of the intruder's annual diet comes from crops
raised in the contaminated soil and from food products
produced by animals. External exposure and ingestion of
contaminated ground water from a well are two pathways
included in this scenario. It is also assumed that a
qu~t~ty of contaminated soil is ingested by a child during
play.or an adult at work in the fields. Inhalation of
re~~p'~nded contaminated soil and the migration of radon
into: the intruder's basement are additional pathways of the
Intruder-Agriculture Scenario.
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Determination - Page 69
.
Direct Gamma - Direct radiation from standing in the
excavated hole.
.
Suspension of Particulates from Construction - Inhalation
of particles suspended during construction, external
exposure from suspended particulates, and exposure to an
area source consisting of particles deposited on the soil
following suspension during construction.
.
Airborne tritium - Inhalation and skin absorption of
airborne tritiated water vapor.
6.2.4 - Intruder-Agriculture Scenario
The Intruder-Agriculture scenario was based on the assumption
that an individual builds a home and lives on the site beginning
today. It was also assumed that the intruder obtains his food
locally and sinks a well into the aquifer underlying the site to
obtain drinking water. In the Intruder-Agriculture scenario,
the intruder is assumed to live in the house, plant a garden in
soil excavated from the waste disposal site during construction,
use water from an on-site well, and raise cattle and milk cows
on the contaminated soil at the site. In addition, a child in
the family is assumed to ingest contaminated soil, and products
of radon decay are assumed to build up indoors due to the radium
contamination in the waste.
6.2.5 - Conclusions of the On-Site Exposure Scenarios
For the Intruder-Trespasser scenario, the direct external
radiation dose rate to a person standing on the trenches depends
on whether the soil overlying the trenches is intact and
uncontaminated. If the overlying soil becomes contaminated as a
result of the "bathtub" effect which is known to occur at the
site, the shielding effectiveness of the overlying soil is
markedly reduced, resulting in dose rates up to approximately
1.4 mremlhpur. If it were assumed that the trespasser frequents
the sit8:;:..~q the average, once per week, spending one hour per
visit, t}ieresultant dose from the Intruder-Trespasser scenario
would be. approximately 73 mrems/year.
If the overlying soil is contaminated as a result of the
"bathtub" effect, wind and mechanical erosion processes could
cause contaminated soil particles to become airborne. Once
airborne, they could cause internal exposures due to inhalation
and also external exposures from immersion in the airborne
particulates.
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Determination - Page 70
Individuals standing in the vicinity of the trenches would
likely be exposed to airborne tritiated water vapor. If the
trench cap degrades and/or the trench leachate overflows,
evaporation processes will result in airborne tritiated water
vapor. The dose to a trespasser from airborne tritiated water
vapor is presented in Table 27.
For the Intruder-Construction scenario, the results revealed
that if a home were constructed at the site today, the dose to
the construction worker over the SOO hours required for
construction is estimated to be 3.2 rems a~d the lifetime risk
of fatal cancer is approximately 1.2 x 10-. Most of this
dose and risk is due to direct radiation, primarily from
cobalt-60, cesium-137, and radium-226. The doses associated
with the Intruder-Discovery scenario are substantially less than
the Intrduer-Construction scenario due to less duration of
on-site activities.
If a 100-year period of institutional controlS is assumed, the
dose and risk to a construction worker at the site decrease by
about an order of magnitude, to 320 mrem. The decrease is due
primarily to the decay of cobalt-60-and cesium-137. However,
direct radiation is still the major contributor to dose, though
the dominant radionuclide is now radium-226.
After a SOO-year period of institutional control, the dose and
risk to the construction worker decrease further, but by less
than a factor of about 2, to 210 mrem. Direct radiation is
still the major contributor to dose, and radium-226 is still the
dominant radionuclide.
For the Intruder-Agriculture scenario, the results revealed that
if a person were to live in a home constructed directly over the
waste trenches today, the dose equivalents to an adult from all
pathways, not including radon, total 26,000 mrem per year for
the average case, with the upperbound estimate totalling
1,000,000 mrem per year. Forty-three percent of the impact
would b.'d.erived from drinking water, 47 percent from food
produced;':'on-site, and 10 percent from external exposure.
Tritium,"'.'carbon-14, strontium-90, and radium-226 dominate the
S - As it is used here, institutional controls includes access
restrictions such as fences, on-site personnel, land use and
deed restrictions and maintenaftce activities such as fence
repair and limited custodial maintenance and monitoring
activities.
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i
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Determination - Page 71
...-1. ;-: -
. TABLE 27
EFFECTIVE DOSE EQUIVALENTS (MREM/HOUR) FOR TRANSIENT INTRUDER
1 2 3 4
Years Direct Gamma ResusĄension
Decay Waste Soil Inhalation-Immersionl
o 4.SE-04 1. 4E+00 1. 4E-Ol 4.9E-08
10 1.7E-04 1. 3E+0 0 1.3E-01 4.SE-08
20 9.7E-OS 1. 3E+0 0 1. 3E-0 1 4.4E-08
30 7.8E-OS 1.3E+OO 1.3E-Ol 4.4E-08
40 7.3E-OS 1. 3E+OO 1. 3E-0 1 4.4E-08
SO 7.1E-OS 1. 3E+OO 1. 3E-0 1 4.4E-08
7S 6.8E-OS 1. 2E+OO 1.3E-Ol 4.3E-08
100 6.7E-OS 1. 2E+0 0 1. 3E-0 1 4.3E-08
200 6.4E-OS 1. 2E+OO 1.2E-01 4.3E-08
300 6.1E-OS 1.2E+00 1. 2E-0 1 4.3E-08
400 S.9E-OS 1.2E+00 1.2E-01 4.3E-08
SOO S.6E-OS 1.2E+00 1. 2E-O 1 4.2E-08
1 Major Contributors are Th-232 and Pu-238
2 Major contributor is Th-232
. -
".'''':.' --
";,'
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Determination - Page 72
ingestion doses, with cobalt-60, cesium-137, and radium-226
dominating the external exposure.
For each year a person lives on-site, the average c,se lifetime
risk of fatal cancer would be approximately 1 x 10- , or one
in 100. Under the same scenario, the upperbound1case lifetime
risk of developing fatal cancer would be 4 x 10- , or four in
10. Both cases significantly exceed EPA's target risk range.
Prolonged exposures (many years of exposure) result in a
lifetime risk of cancer approaching 1. The exposure to radon
progeny was conservatively estimated to be 50 WLM per year,
which corresponds to a lifetime risk of fatal lung cancer of
close to 1. 0 .
If a period of 100 years of site institutional control were
assumed before a person constructs and occupies a home on-site,
the dose decreases and the longer-lived radionuclides such as
radium-226, thorium-232, and plutonium-238 become the
significant radionuclides. Tritium and strontium-90 no longer
contribute to the dose because they.have decayed away. .
Cesium-137 will have decayed to less than 90% of its original
activity.
Assuming occupancy of the site does not begin for 100 years or
more, the doses and associated risks decrease, but by only a
small margin since most of the exposure is associated with the
relatively long-lived radionuclides. If a 100-year period of
institutional control is assumed, the dose associated with an
intruder-agriculture scenario decreases by a factor of
approximately 3, to 7.2 rem/year. Of this dose, the direct
radiation exposures have declined by about a factor of 10, to
780 mrem/year, primarily due to the decay of Cobalt-60.
Radium-226 is now the dominant source of external exposure. At
100 years, the lifetime risk of fatal cancer (not including
radon progeny) due t02continual exposure decreases to
approximat~ly 4 x 10-. The exposures and risks associated
with el8Vat~dlevels of radon progeny indoors decrease only
slightly-~;a.expected, given the long half-life of Radium-226.
If a SOO-year period of institutional control is assumed, the
dose decreases to 5.1 rem/year, and the r~sk (not including
radon progeny) is approximately 3.1 x 10-. The reason for
the small decrease is that the dose from drinking water is
dominated by very long-lived radionuclides. If uncontaminated
sources of drinking water are used, the dose is approximately
600 mrem/year. This dose is primarily due to direct radiation,
which is dominated by Radium-226. The food ingestion pathways
contribute less than 100 mrem/year.
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1 ---
Determination - Page 73
Even after 500 years, on-site occupancy would result in risks
exceeding the acceptable risk range. See Figures 13 and 14 for
an illustration of the decay of radionuclide indicators with
time. It can be seen that beyond 100 years the risks associated
with the MFDS remain unacceptably high and tend to become
constant rather than decreasing significantly; thus, the need
for institutional controls, maintenance and monitoring to be
implemented and funded in perpetuity is apparent.
As the foregoing discussion demonstrates, the threatened release
of hazardous substances from the MFDS, if not addressed by the
preferred alternative or one of the other active measures
considered, may present an imminent and substantial endangerment
to public health, welfare, or the environment.
6.3
Risk Assessment Uncertainties
As with most baseline risk assessments, a number of
uncertainties are associated with the MFDS risk assessment. The
following discussion describes some of those uncertainties which
may have led to an underestimation of the estimated exposures
associated with some of the pathways evaluated:
In the April 1991 final risk assessment, in-transit decay is
assumed for the transport of the radionuclides from the trenches
to the receptor location. The in-transit time for water is
assumed to be several years, and the transit time for many
radionuc1ides is much longer due to the radionuclide binding
coefficients. For some radionuclides, this in-transit decay
assumption results in substantial decay. If the MFDS were to
experience "bathtubbing" (trench overflow) conditions under a No
Action scenario, the radionuclide transit time would be
substantially reduced and, consequently, the concentrations of
radionuclides reaching the potential receptors would be much
greater.
Additionally, the magnitude of retardation for some of the
radionuclid~s, such as plutonium and carbon-14, may have been
overestimated in the risk assessment. Retardation of plutonium
is complex and poorly understood. Plutonium is known to be
fairly mobile under some conditions of valence, complexation,
and colloidal suspension. Plutonium has also been shown to be
in a micro-particulate form in the MFDS trench leachates rather
than in a typical ionic solution state; this may make it more
mobile. Plutonium has also been detected in ground water
migrating away from the trenches in the LMB, indicating that
plutonium is more mobile than would be indicated by the high Kd
values assumed in the risk assessment. Thus, the risk
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FIGURE 14
Determination - Page 75
III ,-, " " , " , , ~-.-,.
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liME, years
MAXEY FLATS FsAEPOAT
MAXEY FLATS SITE RI/FS
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-------
Determination - Page 76
assessment may have underestimated the doses associated with
some of the off-site pathways, in particular, the erosion
pathway. It is for these reasons that EPA feels that the
upperbound dose estimates for the erosion pathway are
appropriate.
The risk assessment assumes migration of leachate to the
hillslope drainage channels with subsequent migration of
leachate to the alluvium, quickly, via surface water runoff.
However, it is likely that leachate will also migrate down the
entire hillslope through the shallow soil-colluvium layer and
enter directly into the alluvial aquifer without major dilution
from uncontaminated surface water. The risk assessment also
assumes that a significant portion of alluvial ground water is
recharged and diluted by stream water. A more appropriate
assumption is that no recharge filtration from upstream water
occurs to the band of contaminated ground water passing through
the alluvium to the creek. This is more appropriate because, in
the MFDS hydrogeological environment, alluvial ground water
flows from the alluvium into the creek (rather than the reverse,
as was assumed in the risk assessment). These factors, as well
as the points made previously with regard to the in-transit
decay and retardation factors, may have resulted in an
underestimation of the potential doses associated with the
off-site well water pathway.
The following uncertainties may have led to an overestimation of
the exposures associated with some of the pathways evaluated:
The average case values for the Intruder-Agriculture well
analysis are all greater than the maximum concentrations
detected in the Remedial Investigation (RI) well sampling, with
the exception of tritium. The tritium data from the RI may have
been skewed by a well near a trench with very high tritium
concentrations. Additionally, trench leachate data is also
skewed toward high concentrations of certain radionuclides,
since s~ific trenches were targeted during the RI because of
the elev~~ed radionuclide concentrations. Since the generation
of leac~ate~is a major component of most of the pathways modeled
in the risk assessment, the model results may be conservative
compared to previous field measurements.
The impacts for individual pathways for the sOO-year timeframe
are the sums of all radionuclides that impact the receptor at
any time during that 500 year span. In other words, impacts
seen from tritium in the early'part of the time frame are added
to those from radium-226, which are seen at the end of the time
frame. This approach tends to overestimate the total dose,
which is used to estimate exceedance ratios.
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Determination - Page 76-A
The 1-129 source term has probably been significantly
overestimated in the risk assessment. The source of three
curies for the MFDS is based on the assumption that 1-129 was at
its detection limit in the waste. Preliminary results of a
recent study indicate that the 1-129 source could be as much as
1000 times lower than its detection limit in low-level
radioactive waste. The industry is still uncertain about the
1-129 source term in low-level waste. Bowever, since 1-129 does
not contribute significantly to the impacts estimated at the
MFDS based on the three curie value, there is no real effect of
adopting the overestimate.
Another uncertainty deals with the Biv value for carbon-14. A
recent study has shown that the Biv tor carbon-14 reported in
Requlatorv Guide 1.109 is as much as 50 times too high.
However, the traditional value was employed in the MFDS risk
assessment. It was thought that the traditional value would be
used until the recent work becomes more widespread. As a
consequence, the dose for carbon-14 from the ingestion of plants
and deer meat may be overestimated.
O. .. -
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Determination - Page 77
SECTION 7.0 - DESCRIPTION OF ALTERNATIVES
7.1
Remedial Action Obiectives
As previously discussed, the primary mechanism for release of
contaminants to the environment from the MFDS is the migration
of leachate from the disposal trenches, through the underlyjng,
fractured bedrock, to the hillslopes surrounding the site. The
major cause of leachate generation is the infiltration of
precipitation through the subsided trench cover. Historically,
trench leachate pumping operations at the MFDS have been
necessary to address trench overflow conditions; thus, trench
overflow is a pathway of concern as well.
Trench subsidence is the lowering of the trench caps due to
trench waste consolidation over time. Areas affected by
subsidence can range in size from a few square feet of a cap to
the entire area of a trench or group of trenches. Subsidence
can cause cap failures by cracking or deforming of the cap
materials. Depressed areas commonly result in ponding of rain
water, which would have run off naturally if subsidence had not
occurred. Both subsidence and ponding can lead to increased
rates of water infiltration into the waste. Subsidence is
evident in most waste disposal trenches. After a few years,
therefore, soil must be added to the trench surfaces and the
caps must be regraded to maintain surface water runoff.
The objectives of remedial action at the MFDS are to:
. Minimize the infiltration of rainwater and ground water into
the trench areas and migration from the trenches;
. St~bilize the site such that an engineered cap that will
require minimal care and maintenance over the long term can
be placed over the trench disposal area;
. Minimize the mobility of trench contaminants by extracting
tre~ .leachate to the extent practicable;
. Promote site drainage and minimize potential for erosion to
protect against natural degradation;
. Implement institutional controls to permanently prevent
unrestricted use of the site;
. Implement a site performance and environmental monitoring
program;
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Determination - Page 78
~. . ..-
- .....
As with any
must be met
environment
federal and
remedial action under Superfund, these objectives
in ways that are protective of human health and the
and achieve applicable or relevant and appropriate
state requirements.
7.2
Alternatives
Eighteen potential remedial alternatives to achieve the remedial
action objectives for the MFDS were developed and evaluated
during the FS. These 18 alternatives were then screened on the
basis of their effectiveness, implementability and cost. This
screening produced a manageable group of seven alternatives.
Each of the seven alternatives was then subjected to a detailed
analysis which applied the nine evaluation criteria established
by the Superfund Amendments and Reauthorization Act (SARA).
The No Action alternative, which is required to be evaluated at
all Superfund sites, serves as a baseline for comparison against
the other alternatives and must be carried through the detailed
analysis of alternatives. The No Action alternative is not an
action-based alternative but rather consists solely of
monitoring and activities in support of monitoring.
with the exception of the No Action
alternatives evaluated incorporates
stabilization as well as horizontal
These technologies are discussed in
alternative, each of the
technologies for trench
and vertical flow barriers.
the following sections.
7.2.1 - Stabilization Technologies
Stabilization at the MFDS refers to the consolidation and
densification of trench soils and/or waste materials. The
purpose of stabilization at the MFDS is to achieve trench
stability such that a vertical infiltration barrier (cap) can be
placed over the trench disposal area which requires minimum
repair and maintenance over the long term.
The dynqp.c;":"compaction technology is a stabilization method
common t.o";"Alternatives 4, 10, and 17. The dynamic compaction
technoloqy involves the repeated dropping of a large weight on
each trench cover (except for those trenches where it is not
appropriate) until the waste and trench cover are sufficiently
consolidated. The weight, or tamper, is dropped using a crane
specially designed for that purpose. As the trench contents
densify, backfill soil is added to the resulting depressions.
The backfill soil is then compacted so that a stable cap can be
constructed over the compacted trenches.
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.
Det~rmination - Page 79
The natural subsidence technology is common to Alternatives 5
and 8. Natural subsidence is the natural densification and
consolidation of soils and waste materials in the trenches over
time. As the waste mass densifies by natural processes, causing
subsidence, the overall rate of subsidence would decrease and
the waste mass would become more stable. As natural subsidence
continues, depressions would form in the overlying cap and these
depressed areas would require backfilling with soil to prevent
the ponding of rainwater and subsequent infiltration of
rainwater into the trenches. Because of the many physical and
chemical variables involved and the limited quantitative
information available, it is not possible to predict accurately
how long it would take for waste trenches to naturally subside
at the MFDS.
Alternative 11 employs the grouting technology as a means of
trench stabilization. The grouting technology would consist of
injecting grout, a mixture of materials (e.g., cement,
bentonite, fly ash, etc.) and water, through specially inserted
probes into the majority of trenches to fill voids and other
openings in the waste. Grouting would stabilize the trenches by
reducing the subsidence that might otherwise occur as the trench
contents settle into the voids. Stabilization could be only
partially achieved by this technology because, although it might
retard deterioration significantly, grouting would not likely
prevent the continuing deterioration and collapse of the waste.
7.2.2 - Flow Barriers
Each action-based alternative that is described in the following
sections utilizes barriers to prevent (1) vertical infiltration
of precipitation to the trench waste, and (2) horizontal
infiltration of ground water through subsurface strata to the
trench waste.
7.2.2.1
Vertical Infiltration Barriers
The fo11awing four types of vertical infiltration barriers are
include4~'&mong the action-based alternatives evaluated:
Structural. Cap, Initial Cap, Engineered Soil Cap with Synthetic
Liner, and Engineered Soil Cap (with all natural materials) .
Alternative 4 employs a structural cap for minimizing vertical
infiltration. The structural cap would consist of a
two-foot-thick reinforced concrete slab over the trenches with a
two-foot-thick clay layer elsewhere. The concrete/clay layer
would be topped by a drainage layer and,a topsoil layer to
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Determination - Page 80
support a vegetative cover. The topsoil and drainage layers
would protect the concrete/clay layer against weathering. They
would also control excessive runoff rates which would minimize
damaging erosive forces. Prior to placement of an initial layer
of compacted soil over the existing trench cover, the trenches
would be dynamically compacted to provide a stable support for
the structural cap. A structural cap would then be placed over
both the compacted trenches and the initial layer of compacted
soil.
Alternative 5 employs an initial cap to serve as a barrier to
vertical water infiltration while the natural stabilization
process takes place, after which a final, multi-media cap would
be installed. The initial cap would consist of a compacted soil
layer6covered with an approximate 30-40 mil thick synthetic
cover. The clay and synthetic material cover would cover an
approximate 40 to 50 acre area. The intent of this approximate
two-foot thick cap is to allow subsidence to occur naturally,
while adding backfill material as necessary to maintain proper
grading for drainage and repairing the synthetic cover as
required. The final cap would be t~e engineered soil cap with
synthetic liner described below.
Alternatives 8, 10, and 11 employ an engineered soil cap with
synthetic liner as a barrier to vertical water infiltration.
Alternative 5 also employs an engineered soil cap with synthetic
liner, to be installed upon completion of the natural
stabilization process. This type of vertical infiltration
barrier consists (from bottom to top) of an initial layer of
compacted soil placed over the existing trench cover, a
two-foot-thick clay layer, an 80 mil (or sufficiently similar)
synthetic liner, a geotextile fabric layer, a one-foot-thick
drainage layer, a geotextile fabric layer, and a two-foot-thick
soil layer supporting a vegetative cover. The composition of
6 - The-~nwealth has proposed use of an initial cap
consist1~9;of: compacted soil cover over the trench disposal
area, topped'with a 25-year life, 60 to 80 mil thick, synthetic
liner with a drainage layer/filter fabric on top, followed by a
layer of topsoil to support a vegetative cover. As discussed in
Section 10.1, the selected remedy includes an initial cap that
does not employ a drainage/vegetative cover. Bowever, an
alternate design, such as the one proposed by the Commonwealth,
may be used if the selected remedy's initial cap can not
effectively. control anticipated rates of surface water runoff
and consequent erosion.
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. ..
i
I
Determination - Page 81
this cap would be designed to provide the most suitable soil
properties and conditions to support and maintain a healthy
vegetative cover (e.g., provide adequate moisture during
prolonged rainless periods). Table 34 provides a description of
the contribution of each layer contained in this type of
vertical infiltration barrier.
Alternative 17 employs an engineered soil cap consisting of all
natural materials as a barrier to vertical water infiltration.
This type of barrier consists of several layers of natural
materials designed and arranged to promote drainage, minimize
infiltration, and provide protection from erosion. The layers
(in order of placement from bottom to top) are: a
four-foot-thick infiltration barrier consisting entirely of clay
or a combination of clay and soil-ben,onite (or equivalent)
layers with a permeability of 1 x 10- cm/sec or less to
provide a barrier against infiltration of precipitation; a
four-foot-thick drainage layer consisting of a mixture of sand,
crushed rock and gravel of high permeability to drain water off
the cap into drainage ditches and away from the disposal
trenches; and, a three-foot-thick sqil layer with an eight-inch
topsoil layer which would support a vegetative cover and allow
infiltration of water (to be carried off through the underlying
drainage layer), thus minimizing surface runoff and
consequential erosion problems.
7.2.2.2
Horizontal Flow Barriers
Two types of potential horizontal flow barriers are included
among the action-based alternatives evaluated: (1) a lateral
drain and cutoff wall combination that encircles the entire
trench area and (2) a cutoff wall that extends from the east
slope to the west slope of the site, beneath the cap and along
its north perimeter (north cutoff wall). Alternatives 4 and 17
employ the lateral drain/cutoff wall combination; Alternatives
5, 8, 10, and 11 employ the north cutoff wall flow barrier.
The lateralo.:drain/cutoff wall would block exfiltration of any
remainin9~leachate in the unlikely event that, without a
hydrostatic head, the leachate could flow through tight fissures
in the rock formations beneath the trenches. Specifically, the
barrier would intercept leachate flow originating from shallow
. trenches and block or contain any leachate originating from
deeper trenches. The lateral drain component of this horizontal
flow barrier would'involve excavation of a trench around the
perimeter of the desired trencn group and installation of a
perforated pipe at the bottom of the trench to collect any
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Determination - Page 82
liquids flowing into the drain. Crushed rock or gravel would
surround the perforated pipe to allow flow into the pipe without
clogging from soil particles. Sumps would be placed at
specified intervals to collect leachate in the pipe; the
leachate would then be solidified and disposed on-site. The
lateral drain would be limited to the more shallow trenches in
the western and central trench series due to practical equipment
limitations.
The cutoff wall component of the lateral drain/cutoff wall
barrier would consist of two sections: an upper section cut
into the surface soil strata and a lower, much deeper section
extending into the rock strata down to the desired depth. The
upper section of the cutoff wall would consist of either a
compacted 9lay key trench or a slurry wall with a permeability
of 1 x 10- em/see or less. The upper section would block
ground water flow at the interface of the soil cover and the
Lower Marker Bed. The lower section of the cutoff wall would
consist of a grout curtain utilizing a cementitious grout or a
cement/bentonite grout. The lower portion, or grout curtain,
would form a barrier against ground. water flow into the trenches
and/or outflow of leachate from the trenches. The cutoff wall
design would include a series of collection wells near the
inside of the wall to facilitate the removal of water mounding
against the barrier. Water collected from these wells would be
solidified for disposal in new trenches.
The second horizontal flow barrier evaluated c09sists of a
cutoff wall without the lateral drain component. The cutoff
wall in this barrier is somewhat different than the previously
described cutoff wall. This cutoff wall, sometimes referred to
as a north cutoff wall, would be a slurry trench (identical to
the upper section of the cutoff wall described above, except
that a gravel drain would be installed near the bottom along its
exterior side) without the grout curtain (lower section of the
cutoff wall described above). The gravel drain along the
exteriorr..side of the wall (exterior to the trench disposal area)
".. -.
7 - The Commonwealth has proposed the installation of a
horizontal flow barrier that would extend down to the Henley Bed
if site monitoring data indicates that lateral recharge of the
trenches is occurring. The selected remedy does not specify the
type, exact location or extent of the horizontal flow barrier,
if one is needed. The Commonwealth's proposal will be
considered during evaluation of the necessity of a horizontal
flow barrier.
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Determination - Page 83
would shunt ground water toward the hillslopes and prevent its
seepage under the wall. By preventing water from entering the
trenches, no new leachate would be generated in the tren9hes.
The wall would be designed for a permeability of 1 x 10-
em/see or less.
7.2.3 - Baseline Features
Each alternative also includes baseline features - features that
are common to all alternatives, with the exception of the No
Action alternative. The baseline features are as follows:
. Non-functional and unstable site structures would be
decommissioned, demolished and buried on-site.
. Additional trenches would be constructed for disposal of
solidified trench leachate and/or waste generated during
site remediation.
. A buffer zone, contiguous to the existing site licensed
property boundary, would be acq~ired. The buffer zone would
encompass an approximate 200-acre area, at a minimum, and
would: (1) ensure long-term access for the purpose of
monitoring to assess remedy compliance; and, (2) control
activities on the hillslopes adjacent to the MFDS to
minimize hillslope erosion.
. Institutional controls would be established and maintained
in perpetuity to prevent unauthorized and/or
inappropriate use of the site.
,
. Monitoring and maintenance activities would be conducted
routinely, and in perpetuity, to assess remedy performance
and to preserve the integrity of the remedy, respectively.
. A remedy review would be performed by EPA at least every
fiva years to ensure the remedy continues to meet the
remedial action objectives, including compliance with state
and-federal ARARs and protection of human health and the
environment.
The remedial alternatives receiving detailed analysis in the
Feasibility Study are summarized in the following sections;
estimated costs and design/construction times are summarized in
Table 29, following the Description of Alternatives.
.
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I
1-
Determination - Page 84
7.2.4 - ALTERNATIVE 1 - NO ACTION
Estimated Construction Cost: $ 636,000
Estimated 0 & M Cost: $ 6,167,000
Estimated Present-Worth Total Cost: $ 6,803,000
Estimated Implementation Time:
6 months
Alternative 1 consists of the following activities:
.
.
.
Site Monitoring
Installation of Additional Monitoring Wells
Repair, Maintenance and Replacement of Monitoring
Equipment
Monitoring activities would consist of the installation of
additional monitoring wells, sample collection and analyses
frequent basis, and repair, maintenance and replacement of
monitoring equipment as needed. The estimated cost of 6.8
million dollars for an alternative involving only monitoring
activities arises from the need to monitor this site in
perpetuity. The No Action alternative is not an engineered
remedial alternative, and it would not satisfy the remedial
objectives. The No Action alternative does not comply with
ARARs and would, likewise, not provide overall protection of
human health and the environment.
on a
7.2.5 - ALTERNATIVE 4 - STRUCTURAL CAP/DYNAMIC COMPACTION/
HORIZONTAL FLOW BARRIER
Estimated Construction Cost: $ 59,332,000
Estimated 0 , M Cost: $ 6,175,000
Estimated Present-Worth Total Cost: $ 65,507,000
Estimated Implementation Time:
38 months
Alternative- 4 includes the following remedial activities:
. ."'::- . .
. TreDCh~Leachate Removal
. Solidification Of Leachate And Disposal In New Trenches
. Installation Of Horizontal Flow Barrier (Lateral Drain/
Cutoff Wall), If Necessary
. Dynamic Compaction Of Existing Disposal Trenches Concurrent
With Addition Of Compacted Soil And Sand Backfill
. Installation Of A Two-Foot-Thick Reinforced Concrete
(Structural) Cap OVer The Compacted Trenches And A
Two-Foot-Thick Low-Permeability Clay Cap OVer The Rest Of
The Trench Disposal Area.
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Determination - Page 85
. Drainage Channel Improvements And Other Necessary
Surface Water Control Features
. Baseline Features
This alternative combines the technologies of trench leachate
removal, dynamic compaction and structural capping. Leachate
would be extracted, solidified, and disposed in newly-
constructed trenches on-site. After leachate removal and
dynamic compaction of the disposal trenches, a reinforced
concrete structural slab and several feet of soil cover would be
placed over the disposal trenches. The use of dynamic
compaction on the trench area prior to placement of the
structural cap would provide a stable foundation for the
minimize future subsidence. The reinforced concrete cap
not be capable of spanning the wide trenches without the
provided by stabilization.
cap and
would
support
The lateral drain/cutoff wall, if found to be necessary, would
help reduce the off-site migration of contaminants and prevent
the infiltration of subsurface water.
7.2.6 - ALTERNATIVE
5 - NATURAL SUBSIDENCE/INITIAL CAP AND FINAL
ENGINEERED SOIL CAP WITH SYNTHETIC
LINER/HORIZONTAL FLOW BARRIER - "NATURAL
STABILIZATION"
Estimated Construction Cost: $ 23,910,000
Estimated 0 & M Cost: $ 9,643,000
Estimated Present-worth Total Cost: $ 33,553,000
Estimated Implementation Time: 22 Months For Initial
Closure Period;
35 - 100 Years For Interim
Maintenance Period Following
Initial Closure period;
. .
10 Months For Final Closure
Period Following Interim
Maintenance Period
. .::..~ - .
'. -. - --.
The implementation of this alternative would involve the
following activities:
. Trench Leachate Removal
. Solidification Of Leachate And Disposal Into New Trenches
. Installation of An Initial Cap And Periodic
Replacement Of Synthetic Liner
. Installation of Horizontal Flow Barrier (North Cutoff
Wall), If Necessary
j
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Determination - Page 86
. Natural Subsidence with Active Maintenance And Monitoring
. Installation Of A Final Engineered Soil Cap with Synthetic
Liner
. Initial and Final Cap Grading And Contouring To
Control Surface Water Flow And Erosion
. Drainage Channel Improvements And Other Necessary
Surface Water Control Features
. Baseline Features
The "Natural Stabilization" alternative8 combines elements of
containment, leachate removal, and treatment. Following
leachate extraction, solidification and disposal, an initial
cap would be installed over the trench disposal area to prevent
infiltration of precipitation into the trenches. The
distinguishing feature of this alternative is the use of an
initial cap during the period of natural subsidence, estimated
to take approximately 35 to 100 years (the Interim Maintenance
Period). This cap would be designed to prevent the infiltration
of rainfall and surface water into the disposal trenches while
subsidence and maintenance are taking place. Cap grading and
contouring would be performed to enhance the control of surface
water flow, better distribute the flow of surface water, and
control and minimize, to the extent practicable, erosion of
hillslopes. Improvements to drainage channels would be
performed to enhance distribution of surface water runoff and to
minimize erosion. Cap repairs and backfilling of subsided areas
would be performed during the Interim Maintenance Period.
8 - The term "closure", in the "Initial Closure Period" and
"Final Closure Period" components of the Natural Stabilization
Alternative, is used in a generic sense to denote sets of
remedial activities to be implemented during those limited time
periods. Neither the term closure nor the designations "Initial
Closure.Eeriod" and "Final Closure period" are used in any
specifi~~~equlatory sense (i.e., AEC or RCRA closure).
-.-
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1---
Dete.rmination - Page 87
The type of initial cap utilized would be contingent upon its
ability to control surface water runon and runoff. Accelerated
rates of hillslope and/or drainage channel erosion would
necessitate a modification to the proposed initial cap design.
A final, multilayer cap with synthetic liner would be installed
at the completion of natural subsidence, at which time the
trenches would form a stable foundation for the final cap.
Additionally, a north cutoff wall would be constructed, if
determined to be necessary, to prevent lateral ground water
infiltration into the disposal trenches. Other types of
horizontal flow barriers, such as a lateral drain/cutoff wall,
could also be considered.
Maintenance requirements. for this alternative would be
significant during the interim maintenance period. Once the
trenches have sufficiently stabilized, the final cap would be
installed and maintenance requirements would be minimal. The
timing of final cap construction would be based upon specific.
subsidence criteria developed in th~ remedial design.
7.2.7 - ALTERNATIVE 8 - NATURAL SUBSIDENCE/ENGINEERED SOIL CAP
WITH SYNTHETIC LINER/HORIZONTAL FLOW
BARRIER
Estimated Construction Cost: $ 34,302,000
Estimated 0 & M Cost: $ 13,105,000
Estimated Present Worth Total Cost: $ 47,407,000
Estimated Implementation Time:
23 months
Alternative 8 includes the following remedial activities:
. Leachate Removal
. Solidification Of Leachate And Disposal In New Trenches
. Installation Of A Horizontal Flow Barrier (North Cutoff
WalX)-to :If Necessary
. Installation Of An Engineered Soil Cap With Synthetic Liner
. Cap-Grading And Contouring To Control Surface Water
Flow And Erosion
. Drainage Channel Improvements And Other Necessary
Surface Water Control Features
. Baseline Features
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Determination - Page 88
Following leachate extraction, solidification and disposal, an
engineered soil cap with synthetic liner would be placed over the
trench dispo~al area to prevent infiltration of precipitation into
the trenches. The cap utilized in this alternative is identical
to the final cap described in Alternative 5. Alternative 8 is
identical to Alternative 5 except for the time of placement of the
final cap. Alternative 8 places the final cap over the trench
disposal area immediately, rather than waiting for subsidence to
run its course during the estimated 35 to 100 year subsidence
period as in Alternative 5. Trench stabilization would be
accomplished by natural subsidence as in Alternative 5 with
repairs to the final cap being made over the period of subsidence.
The required maintenance activities for this alternative would be
high since trench subsidence and resulting repair of the complex
final cap would be significant. Surface water control would be
addressed through cap grading and contouring and drainage channel
improvements. The north cutoff wall would provide a barrier
against infiltration of ground water into the trench area.
7.2.8 - ALTERNATIVE 10 - DYNAMIC COMPACTION/ENGINEERED SOIL CAP
WITH SYNTHETIC LINER/HORIZONTAL FLOW
BARRIER
Estimated Construction Cost: $ 39,538,000
Estimated 0 , M Cost: $ 4,790,000
Estimated Present-Worth Total Cost: $ 44,328,000
Estimated Implementation Time:
35 months
Alternative 10 includes the following remedial activities:
. Leachate Removal
. Solidification Of Leachate And Disposal Into New Trenches
. Installation Of A Horizontal Flow Barrier (North Cutoff
Wall), If Necessary
. Dyn~c Compaction Of Existing Trenches with Concurrent
Addi~ion Of Compacted Soil And Sand Backfill
. In8tallation Of An Engineered Soil Cap With
Synthetic Liner
. Cap Grading And Contouring To Control Surface Water
Flow And Erosion
. Drainage Channel Improvements And Other Necessary
Surface Water Control Features
. Baseline Features
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Determination - Page 89
with Alternative 10, the dynamic compaction technology would be
employed to stabilize the trench wastes artificially rather than
relying on natural subsidence. Prior to dynamic compaction of the
trenches, leachate would be extracted, solidified and disposed
on-site in new disposal trenches.
Upon compaction of the trenches, an engineered soil cap with
synthetic liner would be placed over the trench disposal area to
minimize vertical infiltration of water into the disposal
trenches. The cap would be graded and contoured to control the
rate of surface water flow and minimize erosion to the extent
practicable.
A north cutoff wall (or other sufficient horizontal flow barrier)
would be installed, if determined to be necessary, to control the
infiltration of ground water into the disposal trenches.
7.2.9 - ALTERNATIVE 11 - TRENCH GROUTING/ENGINEERED SOIL CAP WITH
SYNTHETIC LINER/HORIZONTAL FLOW BARRIER
Estimated Construction Cost: $ 61,870,000
Estimated 0 & M Cost: $ 6,989,000
Estimated Present-Worth Total Cost: $ 68,859,000
Estimated Implementation Time:
46 months
Alternative 11 includes the following remedial activities:
. Trench Leachate Removal
. Installation Of A Horizontal Flow Barrier (North Cutoff
Wall), If Necessary
. Grouting Of Accessible Voids In The Existing Disposal
Trenches With Grout Made From Potable Water And/Or Leachate
. Installation Of An Engineered Soil Cap With Synthetic
Liner.
. Cap Grading And Contouring To Control Surface Water
Flow And Erosion
. Dr_~ge Channel Improvements And Other Necessary
Surface Water Control Features
. Baaeline Features
Alternative 11 would achieve trench stabilization by injecting
grout through lances or probes into the majority of trenches for
the purpose of filling voids and other openings in the trenches.
Trench leachate would be extracted and would then be used in the
grout mix for injection into the trenches. Once injected with
grout, the trenches would provide a stable foundation for a trench
-------
Determination - Page 90
cover. An engineered soil cap with synthetic liner would be
placed over the trench disposal area to prevent infiltration of
precipitation into the trenches. The cap would be graded and
contoured to enhance control of surface water runon and runoff and
improvements to drainage channels would be performed to enhance
distribution of surface water runoff and to minimize erosion.
A north cutoff wall (or other sufficient horizontal flow barrier)
would be installed, if necessary, to prevent the infiltration of
ground water into the disposal trenches
7.2.10 - ALTERNATIVE 17 - DYNAMIC COMPACTION/ENGINEERED SOIL CAP/
HORIZONTAL FLOW BARRIER
Estimated Construction Cost: $ 51,920,000
Estimated 0 & M Cost: $ 4,634,000
Estimated Present-Worth Total Cost: $ 56,554,000
Estimated Implementation Time:
38 months
Alternative 17 includes the following remedial activities:
. Leachate Removal
. Solidification Of Leachate with Disposal Into New Trenches
. Installation Of A Horizontal Flow Barrier (Lateral Drain/
Cutoff-Wall), If Necessary
. Dynamic Compaction Of Existing Disposal Trenches Concurrent
With The Addition Of Compacted Soil And Sand Backfill
. Installation Of An Engineered Soil Cap (With All Natural
Materials)
. Cap Grading And Contouring To Control Surface Water
Flow And Erosion
. Drainage Channel Improvements And Other Necessary
Surface Water Control Features
. Baseline Features
. ..
Alternat~ve.17 combines the remedial technologies of capping and
dynamic _~.ompaction to stabilize the trenches. Prior to dynamic
compaction of the trenches, leachate would be extracted,
solidified and disposed on-site in new disposal trenches. The
differences between this alternative and Alternative 10 are the
types of horizontal flow barrier and cap employed. This
alternative would involve installation of a lateral drain/cutoff
wall rather than the north cutoff wall used in Alternative 10 and
the engineered soil cap would De made of all natural materials and
would not c9ntain a synthetic liner as in Alternative 10.
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Determination - Page 91
The cap would be installed over the trench disposal area to
minimize infiltration into the trenches. The cap would be graded
and contoured to enhance control of surface water runon and runoff
and improvements to drainage channels would be performed to
enhance distribution of surface water runoff and to minimize
erosion.
Table 28 lists the alternatives that underwent a detailed analysis
for the MFDS.
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Determination - Page 92
ALTERNATIVE 1
ALTERNATIVE 4
ALTERNATIVE 5
ALTERNATIVE 8
ALTERNATIVE 10
ALTERNATIVE 11
ALTERNATIVE 17
TABLE 28
SUMMARY OF ALTERNATIVES
THAT UNDERWENT A DETAILED ANALYSIS
NO ACTION
STRUCTURAL CAP/DYNAMIC COMPACTION/
HORIZONTAL FLOW BARRIER
NATURAL SUBSIDENCE/INITIAL CAP AND FINAL
ENGINEERED SOIL CAP WITH SYNTHETIC
LINER/HORIZONTAL FLOW BARRIER - "NATURAL
STABILIZATION"
NATURAL SUBSIDENCE/IMMEDIATE ENGINEERED SOIL
CAP WITH SYNTHETIC LINER/HORIZONTAL FLOW
BARRIER
DYNAMIC COMPACTION/ENGINEERED SOIL CAP WITH
SYNTHETIC 'LINER/HORIZONTAL FLOW BARRIER
TRENCH GROUTING/ENGINEERED SOIL CAP WITH
SYNTHETIC LINER/HORIZONTAL FLOW BARRIER
DYNAMIC COMPACTION/ENGINEERED SOIL CAP/
HORIZONTAL FLOW BARRIER
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Determination - Page 93
TABLE 29
COST/SCHEDULE SUMMARY FOR
REMEDIAL ALTERNATIVES
1
4
Costl
6,803,000
Implement,tion
Time=-
Alternative
$
6 Months
5
65,507,000
33,553,000
38 Months
22 Monthga
35 - 100 Years
10 MonthsC
8 47,407,000
10 44,328,000
11 68,859,000
17 56,554,000
23 Months
35 Months
46 Months
38 Months
-----------------------------------------
1 - Cost estimates for the alternatives are present worth costs
which include capital costs and operation and maintenance
costs. All alternatives assume a 4% discount rate for the
purpose of alternative comparison. The actual discount rate
used to establish the remedy trust fund may differ from the
4% discount rate used here.
2 - Includes design and construction time.
a - The Initial Closure Period would be completed in 22 months.
b - The IDterim Maintenance Period would commence upon completion
of the. Initial Closure Period and would take approximately
35 to 100 years for completion.
c - A 10 month Final Closure Period would follow the Interim
Maintenance Period.
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1-
Determination - Page 94
SECTION 8.0 - APPLICABLE OR RELEVANT AND APPROPRIATE REOUIREMENTS
(ARARS)
CERCLA Section 121(d)(2) requires that the selected remedy comply
with all federal and state environmental laws that are applicable
or relevant and appropriate to the hazardous substances,
pollutants, or contaminants at the site or to the activities to be
performed at the site. Therefore, to be selected as the remedy,
an alternative must meet all ARARs or a waiver must be obtained.
Tables 30 and 31 summarize the action-specific and
contaminant-specific applicable or relevant and appropriate
requirements (ARARs) identified for the MFDS. A discussion of how
each ARAR applies to the MFDS is also provided below.
8.1
Action-SDecific ARARs
An action-specific ARAR is a performance, design, or other similar
action-specific requirement that impacts particular remedial
activities. These requirements are triggered by the particular
remedial activities that are selected to accomplish a remedy.
These requirements do not in themse~ves determine the remedial
alternative; rather, they indicate how a selected alternative must
be achieved. The following are action-specific requirements for
the Maxey Flats Disposal Site remedy:
.
OccuDational Safetv and Health (OSHA) Standards
(29 CFR Sections 1910.120. .1000 - .1500. Parts 1926.53.
.650 - .653)
The OSHA hazardous substance safety standards, 29 CFR 1910.120,
.1000 - .1500, are applicable, action-specific requirements for
remedial activities at the MFDS. The OSHA standards (1910.120)
for hazardous substance response actions under CERCLA establish
safety and health program requirements that must be implemented in
the cleanup phase of a CERCLA response. Under the regulations, a
health and safety program will be required for employees and
contractors working at the MFDS. The standards found in 1910.1000
. - .1500 govern CERCLA response actions involving any type of
hazardou..substance that may result in adverse effects on
employees' health and safety. These standards also incorporate
all of the requirements of 29 CFR Part 1926, the OSHA health and
safety standards for construction. The provisions of 29 CFR
1926.650 - .653 are applicable to any excavation, trenching, and
shoring that is undertaken as part of the construction of
trenches, cut-off walls, etc. .
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Determination - Page 95
TABLE 30
SUMMARY OF ACTION-SPECIFIC
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARS)
ADDlicable
Occupational Safety and Health
(OSHA) Standards (29 CFR Parts
1910 and 1926, both in part)
National Emission Standards for
Hazardous Air Pollutants
(40 CFR Part 61, Subpart I)
Kentucky Standards for Protection
Against Radiation (Allowable
Doses In Restricted Areas)
(902 KAR 100:020)
Kentucky Standards for the
Disposal of Radioactive Material
(902 KAR 100:021)
General Kentucky Requirements
Concerning Radiological Sources
(ALARA) (902 KAR 100:015)
Kentucky Hazardous Waste
Management Regulations
(401 KAR Chapter 34, In Part)
ResourcaConservation and
Recovery. Act (RCRA) Hazardous
Waste Management Standards
(40 CFR Part 268)
Kentucky Fugitive Air Emissions
Standards (401 KAR 63:010)
Relevant and ApDroDriate
Occupational Safety and Health
(OSHA) Standards
(29 CFR 1926, in part)
Federal Standards for
Protection Against Radiation
(Allowable Doses in Restricted
Areas) (10 CFR Part 20)
Federal Licensing
for Land Disposal
Radioactive Waste
'part 61)
Requirements
of
(10 CFR
Kentucky Licensing
Requirements for Land
of Radioactive Waste
(902 KAR 100:022)
Disposal
Kentucky Soil and Water
Conservation Requirements
(KRS 262)
Resource Conservation and
Recovery Act (RCRA)
Hazardous Waste Management
Standards (40 CFR Part 264,
In Part)
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Determination - Page 96
TABLE 31
SUMMARY OF CONTAMINANT-SPECIFIC
APPLICABLE OR R~LEVANT AND APPROPRIATE REOUIREMENTS lARARS)
Applicable
Kentucky Standards for Protection
Against Radiation (Allowable
Doses in Unrestricted Areas)
(902 KAR 100:020, Table II of
902 KAR 100:025)
Kentucky Surface Water Quality
Standards (401 KAR 5:026 - :035)
Kentucky Hazardous Waste
Management Regulations
(401 KAR 34:060, Section 5)
Relevant and Appropriate
Federal Standards for
Protection Against
Radiation (Allowable Doses
in Unrestricted Areas)
(10 CFR Part 20.105, .106
and Appendix B, Table II)
Ambient Water Quality Criteria
(Section 304(a)(l) of
the Clean Water Act)
-Kentucky Drinking Water
Standards-Maximum Contaminant
Levels (401 KAR 6:015)
Federal Drinking Water
Regulations - Maximum
Contaminant Levels and
Maximum Contaminant Level
Goals (40 CFR Parts 141,
142 and 143)
National Emission Standards
for Hazardous Air Pollutants
(NESBAPS) (40 CFR Part 61.92)
Kentucky Licensing
Requirements for Land
of Radioactive Waste
(902.KAR 100:022)
Disposal
Federal Licensing Requirements
for Land Disposal of
Radioactive Waste
(10 CFR Part 61.41)
Federal Standards for Uranium
and Thorium Mill Tailings
(40 CFR Part 192)
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Determination - Page 97
The OSHA standards found in 29 CFR 1926.53 are relevant and
appropriate requirements for construction and related activities
involving the "use" of ionizing radiation. While the actions to
be pursued at the MFDS do not, necessarily, involve the"use" of
sources of ionizing radiation or radicactive materials, these
standards do pertain to the substances involved at the site and to
the activities of the workers in undertaking any part of the
remedial action in the restricted area.
.
National Emission Standards for Hazardous Air Pollutants
(NESHAPS) (40 CFR Part 61. SubDart I)
The NESHAPS standards found in 40 CFR Part 61, Subpart I, are
applicable to those portions of remedial action that would result
in fugitive emission of radionuclides into an unrestricted area.
Compliance with this applicable requirement is determined by
calculating the dose to members of the public at the point of
maximum annual air concentration in unrestricted areas, using
EPA-approved sampling procedures and computer codes. The air
emission standard for NRC licensees, which includes the MFDS, is
set at 25 mrem per year to the whole body and ~5 mrem per year to
the critical organ of any member of 'the public.
Kentuckv Standards for Protection Aaainst Radiation
(Allowable Doses in Restricted Areas) (902 KAR 100:020\
The Kentucky regulations found in 902 KAR 100:020 are applicable
requirements for any employee performing work and for any other
individua~ occupying the restricted area during remediation of the
MFDS. These regulations include: limits to total occupational
dose received, limits to airborne exposure in restricted areas,
required surveys to establish compliance, and the use of
appropriate signs, labels, signals and controls to minimize
exposure to radiation.
.
9 - A revision to this Subpart, changing the emission standard
to 10 mrem/year effective dose equivalent, has been promulgated
but the effective date has been stayed.
-------
Determination - Page 98
.
Federal Standards for Protection Aaainst Radiation (Allowable
Doses in Restricted Areas) (10 CFR Part 20)
The requirements found in 10 CFR 20.101 - .103, .210(b)(1),
.203(a) - (c)(5), (d), and Appendix B, Table I are relevant
appropriate for the MFDS. Because Kentucky is an Agreement
its radiation protection standards for protecting against
radiation in restricted areas (902 KAR 100:020 above), as opposed
to the federal standards, are the applicable standards.
.202,
and
State,
.
General Kentuckv Reauirements Concernina Radioloaical Sources
(ALARA) (902 KAR 100:015)
The requirement found in 902 KAR 100:015, Sections 1 and 2, which
requires that all persons "who receive, possess, use, transfer,
own, or acquire" any radioactive sources must make every
reasonable effort to maintain radiation exposures and releases in
unrestricted areas to "as low as reasonably achievable" (ALARA),
is applicable to the MFDS.
.
Kentuckv Fuaitive Air Emissions Standards (401 KAR 63:010)
The fugitive air emissions standards found in 401 KAR 63:010 are
applicable to the MFDS remedial activities because they apply to
potential operations such as cap installation, excavation of
disposal trenches, demolition activities, and other activities
that may emit dust and other air contaminants. The standards
require individuals to take reasonable precautions to prevent
particulate matter from becoming airborne when material is handled
or processed, a building is constructed, altered, or'demolished,
or a road is used. Visible fugitive dust emissions must be
contained within the lot line of the property on which the
emissions originate.
.
Kentuckv Standards for the DisDosal of Radioactive Material
(902 KAR 100:021)
The radioactive waste classification system and the radioactive
waste characteristics requirements, found in Sections 7 and 8 of
902 KAR 100:021, are applicable requirements for the waste,
disposed of during the remediation of the MFDS. Section 7
provides the criteria for classifying waste for near-surface
disposal. Section 8 contains minimum waste handling requirements
for waste disposed of in new trenches, packaging requirements,
permissible waste characteristics, and stability requirements of
waste generated during remediation of the MFDS.
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Det~rmination - Page 99
.
Kentucky Licensinq Requirements for Land Disposal of
Radioactive Waste (902 KAR 100:022\
Sections 14, 19, 21, 23, 24(1) - (11), 25(3) and 27(2) of
100:022 are relevant and appropriate requirements for the
of waste generated during remediation in new units at the
The Kentucky Licensing Requirements for Land Disposal of
Radioactive Waste specify that closure shall be designed to
achieve long-term stability and isolation of the radioactive
waste, to protect against inadvertent intrusion, and to eliminate,
to the extent practicable, the need for on-going, active
maintenance of the disposal site so that only surveillance,
monitoring, and minor custodial care is required. The regulations
further provide for post-closure surveillance of the site, which
includes a monitoring system that provides early warning of
releases of radionuclides before they reach the site boundary, and
institutional control requirements.
902 KAR
disposal
MFDS.
Federal Licensinq Requirements for Land Disposal of
Radioactive Waste (10 CFR Part 61)
The requirements found in 10 CFR Part 61.29, .42, .44, .51(a),
.52(a)(1) - (11), .53(d), .55 and .56 are relevant and appropriate
for new disposal units at the MFDS. Section 61.41 will be treated
as relevant and appropriate provided the new trenches are located
in a manner that allows compliance with the standard to be
measured at the boqndary of the Restricted Area without
interference from radionuclides migrating from existing trenches.
Sections 61.42, .44, .51(a), .52(a) (6), .53(d), and .59(b) are
relevant and appropriate with respect to the caps, monitoring
system and institutional controls at the MFDS.
.
Kentuckv Soil and Water Conservation Requirements
(Chapter 262 of Kentuckv Revised Statutes)
Chapter 262 of the Kentucky Revised Statutes, which provides for
the establishment of soil and water conservation requirements to
prevent and control soil erosion, are relevant and appropriate
requirements for the MFDS. Remedial activities could create
changes in soil conditions and surface water flow. Thus, the
generally applicable requirements for the technologies/actions
that could lead to large-scale soil disturbance are relevant and
appropriate.
.
-------
Determination - Page 100
.
Kentuckv Hazardous Waste Manaqement Requlations
(401 KAR Chapter 34)
Federal regulations under the Resource Conservation and Recovery
Act (RCRA) establish minimum national standards defining the
acceptable management of hazardous waste. States can be
authorized by EPA to administer and enforce RCRA hazardous waste
management programs in lieu of the Federal program if the States
have equivalent statutory and regulatory authority. If the CERCLA
site is located in a State with an authorized RCRA program, the
State's promulgated RCRA requirements will replace the equivalent
Federal requirements as potentially ARAR. If the State is
authorized for only a portion of the RCRA program, both Federal
and State standards may be ARARs.
Since EPA has delegated the Resource Conservation and Recovery Act
(RCRA) program to Kentucky, the Kentucky hazardous waste
management regulations are applicable, except for requirements
such as those promulgated under the Hazardous and Solid Waste
Amendments of 1984 (HSWA), which have not yet been delegated to
Kentucky.
Radioactive Shipment Records for the MFDS indicate the disposal of
Liquid Scintillation Vials (LSVs) at the site. LSVs, during the
1963 to 1977 site disposal period, typically contained a xylene or
toluene solvent base. The fluids from LSVs containing xylene and
toluene are considered RCRA spent solvent, listed hazardous
waste. Sample analyses detected the presence of low levels of
toluene and xylene in trench leachate during the MFDS Remedial
Investigation. Consequently, the leachate at the MFDS is
considered to be a listed hazardous waste.
Although disposal of the LSVs at the MFDS originally occurred
prior to the effective date of RCRA Subtitle C regulations
(November 19, 1980), the selected remedy for the MFDS will
constitute disposal of a hazardous waste via the extraction,
solidification and disposal of approximately three million gallons
of trena.b..l.,achate on-site. Thus, the RCRA requirements, or their
Kentucky: counterparts, are applicable to the MFDS.
The following Kentucky Hazardous Waste Management regulations are
ARARs that must be met by the selected remedy:
401 KAR 34:060 - Ground Water Protection: Sections 8 and 9 set
forth general ground water monitoring requirements and detection
monitoring program requirements. Sections 10 and 11 set forth
-------
Determination - Page 101
standards for the compliance monitoring program and corrective
action programs which establish how the data gathered will be
evaluated and what actions must be taken to eliminate
contamination of ground water. Should ground water monitoring in
the alluvium indicate Maximum Concentration Limits (MCLs/MCLGs)
have been exceeded, the selected remedy must implement corrective
action to comply with the MCLs/MCLGs.
401 KAR 34:070 (Sections 2, 5, 7, 8 and 10) - Closure and
Post-Closure: Section 2 sets out closure performance standards
which, among other requirements, are intended to minimize the need
for further maintenance and control, minimize or eliminate to the
extent necessary post-closure escape of hazardous constituents to
ground or surface water or through the atmosphere, to protect
human health and the environment.
Section 5 provides for the disposal or decontamination of
equipment, structures, and soils. Section 7 requires a survey
plat to be submitted to the local zoning authority and the
Commonwealth. Section 8 provides for post-closure care and use of
property. Section 10 requires a no~ation on the deed to the
property noting the previous management of hazardous wastes
thereon and the land use restrictions resulting from that use.
401 KAR 34:190 - Tanks: 401 KAR 34:190 regulates tank systems
that are used for treatment and storage of hazardous waste.
401 KAR 34:230 Landfill Closure Standards: Section 6 provides
standards for covers (caps) for sites where waste is left in
place. These standards will apply to the design of the final cap
at the MFDS.
Resource Conservation and Recoverv Act (RCRA) Hazardous
Waste Manaaement Standards (40 CFR Part 268)
Although EPA has delegated the RCRA program to Kentucky, those
federal hazardous waste management regulations promulgated under
HSWA, whicb~have not been delegated to Kentucky, are also
applicable to the MFDS. Specifically, 40 CFR Part 268, which sets
out Land Disposal Restrictions (LDRs), is applicable to the HFDS.
The LDRs require hazardous wastes to be treated to specified
levels prior to land disposal. The LDRs are waived for remedial
. action at the MFDS; see Section 8.3 - ARARs Waiver of this Record
of Decision.
.
-------
Determination - Page 102
The requirements of 40 CFR 264, related to minimum technology
trench design requirements, are neither applicable nor relevant
and appropriate to the remedial actions at the MFDS for those
disposal trenches constructed within the Area of ContaminationlO
(AOC) for the MFDS. The RCRA minimum technology requirements are
not applicable because disposal of solidified trench leachate will
not occur in a new RCRA unit, a lateral expansion of an existing
unit, or a replacement unit. The selected remedy presumes that
sufficient space is currently available within the AOC for the
desired number of new disposal trenches to be constructed.
However, if spacial limitations necessitate construction of new
disposal trenches outside the Area of Contamination, minimum
technology trench design requirements would be applicable
requirements. For the MFDS, the AOC is best described as the
entire area of the Restricted Area, an approximate 400 foot wide
area parallel to the entire western boundary of the Restricted
Area, an area 400 feet by 400 feet at the northwest corner of the
Restricted Area, and an approximate 700 feet wide area parallel to
the entire east boundary of the Restricted Area. The AOC, as
illustrated in Figure 15, is subject to redefinition should new
information become available, through additional site sampling,
which indicates the presence of additional areas of contamination
contiguous to the current AOC.,
While minimum technology trench design requirements might be
considered relevant to the disposal of hazardous waste at the
MFDS, EPA does not consider them appropriate for the MFDS based
upon such factors as the very low concentrations of chemical
constituents relative to the threat posed by the radioactivity at
the MFDS; the potentially significant increased infiltration into
the trenches as a result of the much greater surface area that
minimum technology trenches would require at the MFDS due
primarily to the restrictive site geology; and, EPA's assessment
that no appreciable additional level of protection to public
health or the environment will be gained by imposing these
requirements at the MFDS.
10 - An Area of Contamination (AOC) is delineated by the areal
extent (or boundary) of contiguous contamination. Such
contamination must be contiguous, but may contain varying types
and concentrations of hazardous substances. An example of an Area
of Contamination includes a landfill and the surrounding
contaminated soil.
-------
FIGURE,S
~
o
--
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. -,:C-._~~~~~~ 1~ ~~\~(,~ ,,'~
QI
00
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o
.....
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e
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500
I
soo
1000
o
.
SCALE IN FEET
)()()()(
FENCE ENCLOSING
BURIAL AREA
MFDS PROPERTY BOUNDARY
MAXEY FLATS
EXECUTIVE SUMMARY
MAXEY FLATS SITE RIIFS
EBASCO SERVICES INCORPORATED
MAXEY FLATS DISPOSAL SITE-
SITE MAP
FIGURE 1
-------
Determination - Page 104
8.2
Contaminant-Specific ARARs
Contaminant-specific ARARs set health or risk-based concentration
limits or ranges in various environmental media for specific
hazardous substances, pollutants, or contaminants. Examples of
such media are air and water. These ARARs set protective cleanup
levels for the contaminants of concern in the designated media or
indicate an acceptable level of discharge into a particular medium
during a remedial activity.
Kentucky Standards for Protection Aaainst Radiation
(Allowable Doses in Unrestricted Areas) (902 KAR 100:020
and Table II of 902 KAR 100:025)
Sections 7 and 8 of 902 KAR 100:020 and Table II of 902 KAR
100:025, Section 2, provide general and isotope-specific radiation
protection standards for individuals in unrestricted areas, and
are applicable requirements for the radioisotopes at the MFDS.
Section 7 requires that individuals in unrestricted areas should
not receive a dose to the whole body in excess of 500 mrem in any
year. Section 8 establishes limits, on an isotope-by-isotope
basis, on the amount of radiation that can be released to
unrestricted areas. Specifically, the section provides that
radioisotopic concentrations in air and water above natural
background cannot exceed the limits in 902 KAR 100:025, Table II.
.
.
Federal Standards for Protection Aaainst Radiation
(Allowable Doses in Unrestricted Areas)
(10 CFR Part 20.105. .106 and Appendix B. Table II)
Because of Kentucky's Agreement State status, its radiation
protection standards provide the applicable requirements for
protection against radiation in unrestricted areas at the MFDS.
The analogous federal radiation protection standards found in 10
CFR Part 20.105, .106, and Appendix B, Table II are relevant and
appropriate contaminant-specific standards for the MFDS. The
federal standards were lowered in May 1991 so as to limit the
allowabl~doBe in unrestricted areas to 100 mrem/year and to
provide .pecific radionuclide concentrations in Appendix B, Table
II. In that these new federal standards are more stringent than
the Kentucky regulations, the federal standards shall be the
governing ARARs for allowable doses in unrestricted areas.
.
Kentucky Surface Water Quality Standards
(401 KAR 5:026 - :035) "
Kentucky's Surface Water Quality Standards, set out in 401 KAR
5:026 - :035, set "minimum criteria applicable to all surface
waters". These criteria include" specific limits on
-------
Det~rmination - Page 105
radionuclides. These standards are applicable
contaminant-specific standards for the surface water streams
(i.e., Drip Springs Hollow, No Name Hollow, and Rock Lick Creek)
surrounding the MFDS. In addition, to the extent that the site
contains surface waters as defined by 401 KAR 5:029 Section 1(bb),
including intermittent streams with well defined banks and beds,
the surface water standards are, likewise, applicable
contaminant-specific standards.
Ambient Water Qualitv Criteria
(Section 304(a)(11 of the Clean Water Act)
The EPA water quality 'criteria found in Section 304(a)(1) of the
Clean Water Act are relevant and appropriate criteria for the
MFDS. The EPA criteria for protection of aquatic life from acute
or'chronic toxic effects or the human health criteria for
consumption of fish, whichever is more stringent, is the relevant
and appropriate requirement for the surface waters at and around
the MFDS.
.
.
Kentuckv Drinkina Water Standards - Maximum Contaminant
Levels (401 KAR 6:015)
The Kentucky drinking water standards establish maximum
concentration levels for a number of inorganic, organic, and
radionuclide contaminants. The MCLs established in 401 KAR 6:015
are relevant and appropriate requirements for the MFDS.
Compliance with these ARARs will be judged beginning at the
contact of the alluvium with the hillside and ending at the
streams. Figure 16 provides an outline of alluvial deposits where
drinking water standards will be enforced.
.
Federal Drinkina Water Reaulations - Maximum Contaminant
Levels and Maximum Contaminant Level Goals (40 CFR Parts
141. 142. and 143)
On January 30, 1991, EPA promulgated the new Safe Drinking Water
Act (SDWAL,I~ational Primary Drinking Water Regulations (Phase
II). See 56 Federal Register 3526 (January 30, 1991) (to be
codified at 40 CPR Parts 141, 142, and 143). The Phase II
National Primary Drinking Water Regulations establish Maximum
Contaminant Level Goals (MCLGs) and Maximum Contaminant Levels
(MCLs) for 31 contaminants, which are effective July 30, 1992. A
second regulation, promulgated in July 1991, established MCLGs and
MCLs for five additional contaminants. MCLs are enforceable
standards that apply to specified contaminants which EPA has
determined have an adverse effect on human health above certain
levels. MCLGs are non-enforceable health-based goals that have
been established at levels at which no known or anticipated
adverse health effects occur and which allow an adequate margin of
safety.
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Determination - Page 106
EXPLANATION
ttfK HfSTHlC'tO AHCA
O
a
MAXl V FIATS SITi Rl/f S
tBASCO SCBVICtS INLURPIIH A I HI
OUTLINE OF ALLUVIAL DEPOSITS
WHERE STANDARDS WILL BE APPLKU
AS RELEVANT AND APPROPRIATE
» IGUBi A 1
-------
,---
Determination - Page 107
Under the NCP, EPA requires that MCLGs set at levels above zero
(non-zero MCLGs) be attained during a CERCLA cleanup where they
are relevant and appropriate. Where the MCLG is equal to zero,
EPA sets the cleanup level to be the corresponding MCL. The MCLs
and all non-zero MCLGs are relevant and appropriate requirements
that must be achieved at the MFDS because ground or surface waters
at the site are current or potential sources of drinking water.
The recently added MCLs and MCLGs will supplement the Kentucky
MCLs as relevant and appropriate requirements at the MFDS, and
compliance with these ARARs will be judged at the contact of the
alluvium with the hillside and ending at the streams. These
criteria are presented in Appendix B to this Record of Decision.
Kentuckv Hazardous Waste Manaaement Reaulations
(401 KAR Chapter 34)
401 KAR 34:060 (Section 5) - Ground Water Protection: Section
5 establishes maximum ground water concentration limits for
certain metals and organic compounds. Given the specific
characteristics of site topography and geology, the first point
beyond the waste management area boundary at which corrective
action would be technically practicable is at the contact of the
alluvium with the hillslopes. . Given the institutional control and
perpetual maintenance features of the remedy to be implemented,
this is also the first point at which the public could be exposed
to contaminated ground water. Compliance with maximum ground
water concentration limits will, therefore, be judged at the
contact of the alluvium with the hillslopes.
.
.
National Emission Standards for Hazardous Air Pollutants
(NESHAPs) (40 CFR Part 61. Subpart H)
The NESHAPs for radionuclides in 40 CFR Part 61, Subpart H,
establish an effective dose equivalent of 10 mrem/year for
Department of Energy facilities. This standard is relevant and
appropriate to the MFDS and compliance with this requirement will
be judged at the current site licensed property boundary.
Ke~tuckv Licensina Reauirements for Land Disposal of
Radioactive Waste (902 KAR 100:022)
The 25 mrem/year dose limit found in Section 18 of 902 KAR 100:022
is a relevant and appropriate requirement for the MFDS.
Compliance with the 25 mrem/year standard will be judged on the
combined doses contributed by air, water, drinking water and soil
pathways. The point of compli4nce for this requirement will be
the current site licensed property boundary.
.
I
I
J
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Determination - Page 108
.
Federal Licensinq Requirements for Land Disposal of
Radioactive Waste (10 CFR Part 61.41\
Because Kentucky is an Agreement State, its radiation protection
standards provide the standards for protecting against radiation
in the general environment. Nevertheless, the analogous federal
standard (10 CFR Part 61.41) to 902 KAR 100:022, Section 18 is
relevant and appropriate.
Federal Standards for Uranium and Thorium Mill Tailinqs
(40 CFR Part 192\
The UMTRCA standard found in 40 CFR Part 192.12(a)(1), which
applies to remedial actions at inactive uranium processing sites,
limits radium-226 concentrations in soil to 5 pCi/gram in the top
15 centimeters. Radium-226 is present at the MFDS. Therefore,
EPA has determined that the referenced UMTRCA standard is relevant
and appropriate for the MFDS remedial action and is a
contaminant-specific ARAR for soils at the Maxey Flats site.
.
8.3
ARARs Waiver
CERCLA Section 121(d) provides that, under certain circumstances,
an ARAR may be waived using one (or more) of the following
waivers:
. Interim Remedy Waiver - The remedial action selected is
only a part of a total remedial action that will attain such a
level or standard of control when completed. (CERCLA
121(d) (4) (A).)
. Greater Risk to Health and the Environment Waiver -
Compliance with such requirement at the facility will result in
greater risk to human health and the environment than
alternative options. (CERCLA 121(d)(4)(B).)
. Technical Impracticability Waiver - Compliance with such
requir...nt is technically impracticable from an engineering
perspective~ (CERCLA 121(d)(4)(C).)
. Equivalent Standard of Performance Waiver - The.remedial
action selected will attain a standard of performance that is
equivalent to that required under the otherwise applicable
standard, requirement, criteria, or limitation, through use of
another method or approach. . (CERCLA 121(d)(4)(D).)
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Determination - Page 109
. Inconsistent Application of State Standard Waiver - With
respect to a State standard, requirement, criteria, or
limitation, the State has not consistently applied (or
demonstrated the intention to consistently apply) the standard,
requirement, criteria, or limitation in similar circumstances at
other remedial actions. (CERCLA 121(d)(4)(E).)
. Fund-Balancing Waiver - In the case of a remedial action to
be undertaken solely under Section 104 using the Fund, selection
of a remedial action that attains such level or standard of
control will not provide a balance between the need for
protection of public health and welfare and the environment at
the facility under consideration, and the availability of
amounts from the Fund to respond to other sites which present or
may present a threat to public health or welfare or the
environment, taking into consideration the relative immediacy of
such threats. (CERCLA 121(d)(4)(F).)
At the MFDS, fifteen trench leachate samples were collected and
analyzed for a variety of organics and inorganics during the RI.
Additionally, RCRA analyses (pH, sulfide screen, ignitability
screen) were performed on all fifteen samples. All samples tested
negative for the RCRA parameters analyzed. Very low levels of
organics were detected during the RI (e.g., toluene ranged from
not detected to 5.3 parts per million, xylene ranged from not
detected to 4.4 parts per million). The organic and inorganic
analyses performed on the trench leachate indicate that Extraction
Procedure (EP) Toxicity tests and Toxicity Characteristic
Leachability Procedure tests would be negative for the fifteen
samples. Therefore, RCRA characteristic levels would not be
expected in the leachate once it is extracted and batched during
RD/RA. Nontheless, the documented disposal of a listed waste at
the MFDS (liquid scintillation vials containing xylene and
toluene), and the presence of xylene and toluene in trench
leachate, triggers RCRA requirements (or their Kentucky
counterparts) as applicable to the MFDS.
..
Based ott;~~e.very low levels of chemical constituents detected in
trench ~.achate during RI sampling, it is unlikely that batched
leachate would contain hazardous waste at levels above those which
trigger prohibition of land disposal under Part 268. No further
leachate testing for listed constituents or for waste at
potentially characteristic levels is planned because, based on
factors including those discussed below, EPA has determined that
it is appropriate to invoke a waiver at this time.
~
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Determination - Page 110
During remedial action, approximately three million gallons of
trench leachate will be extracted, batched, mixed with solidifying
agents, and then disposed on-site in new disposal units. The
leachate to be solidified includes concentrations of tritium as
high, or higher than, 12,000,000 pCi/ml, Strontium-90 up to 2,000
pCi/ml, Plutonium-238 up to 320 pCi/ml, and Uranium-233/234 up to
130 pCi/ml. The objective of the leachate solidification program
is to produce a solid, physically stable form of the leachate,
thereby minimizing the mobility of radionuclides within the
newly-constructed trenches. Treatment processes intended to
remove the chemical portion of the leachate will significantly
increase site worker exposure to radiation. In addition,
by-products from treatment processes would require further
handling, treatment and disposal, thereby further increasing
worker exposure to radiation.
Risks associated with the MFDS are primarily due to potential
exposure to radionuclides rather than the very low concentrations
of chemical constituents detected at the site. However, measures
taken to contain the radionuclides within the site (e.g.,
solidification and capping), will be effective in containing the
chemical constituents as well. Thus, the implementation of
treatment processes to remove the minor fraction of chemical
constituents is not necessary to protect human health and the
environment.
EPA has determined that compliance with 40 CFR Part 268 during
remedial action at the MFDS would result in a greater risk to
human health and the environment due to the volume of leachate to
be treated and nature of the leachate and is hereby invoking a
waiver of these requirements.
'.:.., .
..". .
.. ':"- .'~ ..
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Determination - Page III
SECTION 9.0 - SUMMARY OF THE COMPARATIVE ANALYSIS OF
ALTERNATIVES
9.1
Evaluation Criteria
Nine criteria are used to evaluate alternatives at Superfund
sites. These nine criteria are categorized into three groups:
threshold criteria, primary balancing criteria, and modifying
criteria. The threshold criteria must be satisfied in order for
an alternative to be eligible for selection. The primary
balancing criteria are used to weigh major tradeoffs among
alternatives. Generally, the modifying criteria are taken into
account after public comment is received on the Proposed Plan.
The nine criteria are as follows:
Threshold Criteria:
. Compliance with ARARs - Compliance with ARARs addresses
whether a remedy will meet all of the ARARs of Federal and
State environmental laws and/or justifies a waiver.
. Overall protection of human health and the environment -
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.
Primary Balancina Criteria:
. Short-term effectiveness - Short-term effectiveness
addresses the period of time needed to achieve protection
and any adverse impacts on human health and the environment
that may be posed during the construction and implementation
period, until remedial action objectives are achieved.
. Lon~;teim effectiveness - Long-term effectiveness refers to
expected residual risk and the ability of a remedy to
maintain reliable protection of human health and the.
environment over time.
. Reduction of toxicity, mobility or volume - Reduction of
toxicity, mobility, or volume through treatment is the
anticipated performance of 'the treatment technologies a
remedy may employ.
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Determination - Page 112
Primary Balancinq Criteria (Continued):
. Implementability - Implementability is the technical and
administrative feasibility of a remedy, including the
availability of materials and services needed to implement a
particular option.
. Cost - Cost includes estimated capital and 0 & M costs, also
expressed as net present-worth costs.
Modifvinq Criteria:
. State acceptance - State acceptance indicates whether, based
on its review of the RIfFS Reports and Proposed Plan, the
State concurs with, opposes, or has no comment on the
preferred alternative.
. Community acceptance - Community acceptance summarizes the
public's general response to the alternatives, based on
public comments received during. the public comment period.
9.2
ComDarative Analvsis
ComDliance With ARARs
All of the alternatives, with the exception of Alternative 1, No
Action, comply with all ARARs for the MFDS, or obtain an ARARs
waiver as allowed under CERCLA Section 121(d). Since
Alternative 1, the No Action alternative, does not meet the
threshold criteria (does not achieve ARARs, does not provide
overall protection of human health and the environment),
Alternative 1 will not be evaluated further in this comparative
analysis.
Overall Protection of Human Health and the Environment
All of t~.'.remedial alternatives provide overall protection of
human h~t~ and the environment. However, the remedial
alternat~ves have varying degrees of uncertainty associated with
with long-term stability and potential release of contaminants.
Alternative 5 provides the best assurance that, once the final
cap is installed, cap maintenance will be at a minimum.
Additionally, Alternative 5 is the least likely to involve
container rupture and subseque~t contaminant release.
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Determination - Page 113
In that wastes would be left at the site above health-based
levels under each of the alternatives, the selected remedy will
necessarily undergo an EPA-conducted review every five years
following commencement of remedial action. The purpose of this
review process is to ensure that the remedy prevents water
infiltration into the trenches, mitigates hillslope erosion to
the extent practicable, and minimizes the migration of site
contaminants. Modifications to the remedy would occur through
a Record of Decision amendment process if it were determined
during a five-year review, or at any point between, that the
remedy was not providing overall protection of human health and
the environment.
Short-Term Effectiveness
Alternative 5 provides the greatest short-term effectiveness of
the seven alternatives evaluated because it achieves initial
capping of the trench disposal area earlier than any other
alternative and with less exposure of site workers to
radiation. Alternative 8 is only slightly less effective than
Alternative 5, the principal difference being the greater amount
of materials handling required for Alternative 8. Both of these
natural subsidence alternatives (5 and 8) provide greater
short-term effectiveness than Alternatives 4, 10 and 17, which
use dynamic compaction to achieve stabilization, because dynamic
compaction has a greater potential for exposing workers to
direct radiation. Alternatives 4, 10 and 17 are roughly equal
with respect to short-term effectiveness, but 10 provides a
slightly greater degree of short-term effectiveness. The lack
of a synthetic liner feature of Alternative 17 and the
structural cap component of Alternative 4 make them less
effective in the short term.
Alternative 11, grouting, is clearly the most hazardous to
implement of the six alternatives and, therefore, is the least
effective in the short term. Injecting more than 21 million
gallons of grout into LLRW trenches at high injection rates and
high pre..ures would be far more hazardous than any other
activity~considered for remediation of the site.
Lona-Term Effectiveness
. Alternative 5 provides a greater degree of long-term
effectiveness overall than do .the dynamic compaction
alternatives even though, during the interim maintenance period
of Alternative 5, a maintenance staff would be required to
perform frequent inspections and to make prompt repairs
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l~-
Determination - Page 114
following subsidence. This is because when the final cap is
installed after an approximate 35 to 100 years, the amount of
data that would be available for assessing stability would
likely provide more certainty of stability than can be predicted
about the dynamic compaction alternatives (10 and 17).
Moreover, the dynamic compaction alternatives could result in
the release of additional radionuclides due to container rupture
during the compaction process, whereas Alternative 5 would allow
for continued radionuclide decay and containerization for a
longer period of time. Thus, while initial maintenance
requirements are more intense for Alternative 5, the dynamic
compaction alternatives may result in increased monitoring and
maintenance to address the potential increased source term and
long-term stability.
Alternative 10 provides a slightly greater degree of long-term
effectiveness than Alternative 17 because Alternative 10 has the
synthetic liner in the cap to provide a back-up to the clay
layer.
Alternative 11 provides less long-term effectiveness than
Alternative 5. While grouting (Alternative 11) would provide
greater stability than natural stabilization during the early
years, and possibly well beyond the early years, ultimately,
natural stabilization would provide more stability. Because
grout used in Alternative 11 would fill only the accessible
voids at the time of grout injection, at some unpredictable
time, one or more trenches might have a major subsidence and
permit water to infiltrate the trenches. By contrast,
Alternative 5 would be easy to repair, and the maintenance staff
would likely discover the subsidence before water infiltrated
the trenches.
Alternative 8 would require more frequent maintenance than
Alternative 4; however, two potential major repair problems
Alternative 4 - concrete cracking and water infiltration -
result in it providing a lesser degree of long-term
effecti~.ane_ss .
Reduction of Toxicitv. Mobilitv or Volume
with
Because radioactivity is an intrinsic property of the nuclides
in the trench leachate and other media at the site, leachate
toxicity cannot be altered by treatment. Time is the principal
means by which the toxicity of radionuclides is reduced.
Toxicity is reduced by decay of the radionuclides to
concentrations at which they no longer present a threat to human
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1-
Determination - Page 115
health and the environment. None of the alternatives evaluated
employ a treatment technology aimed at satisfying the reduction
of toxicity evaluation factor. However, mobility and volume can
be addressed by treatment; decreasing mobility has a direct
impact on health and safety since decreased mobility results in
longer travel times for radionuclides and a decrease in activity
resulting from radionuclide decay.
Reduction of the mobility of site radionuclides is achieved in
varying degrees by each of the alternatives evaluated. All
remedial alternatives involve the extraction, solidification and
on-site disposal of solidified trench leachate. The
solidification of radioactively contaminated water does not
destroy or alter the radioactivity, but changes its form to a
physically stable mass which binds the radionuclides 60 that
they are far less mobile than they were in their liquid form.
Approximately three million gallons of trench leachate will be
solidified and disposed; thus, a significant reduction of the
mobility of trench leachate would be accomplished by each of the
alternatives. However, other factors, as discussed below,
result in some alternatives being more acceptable than others in
terms of mobility.
Other than exhumation and off-site disposal of the contaminated
media at the site, a significant reduction in volume at the MFDS
is not currently attainable. Exhumation and off-site disposal,
while physically possible to perform, would result in
unacceptably high doses to site workers involved in excavation
of the solid wastes in the trenches. Additionally, due to the
activity of some of the waste present at the site, and the
volume of waste involved, no present-day commercial low-level
waste facility would likely accept the waste. Furthermore,
exhumation would not meet 902 KAR 100:015 which, as an
applicable action-specific requirement for the MFDS. 902 KAR
100:015 requires exposures to be kept to as low as reasonably
achievable.
The following factors were used to evaluate the alternatives
against.the- reduction of toxicity, mobility or volume criteria:
release of trench contaminants due to waste container rupture,
the ability of an alternative to prevent infiltration of water
and subsequent generation of new leachate, and the generation of
contaminated material (increase in the volume of waste).
Alternatives 5 and 8 are the superior alternatives in terms of
reducing mobility and volume for several reasons. First, they
do not involve the forced consolidation of trench waste;
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Determination - Page 116
therefore, the potential for release of radionuclides is not as
great as the dynamic compaction alternatives (4, 10 and 17).
Second, Alternatives 5 and 8 are superior to the grouting
alternative (11) because they do not generate waste grout
resulting from grout setup prior to injection or grout
break-through, which must then be disposed of on-site.
Alternative 11 is more effective than Alternatives 4, 10 and 17
because the grout would solidify and may fixate the contaminants
and would result in a more predictable trench chemistry.
Alternatives 10 and 17, which utilize dynamic compaction, result
in a more complex trench chemistry with a less than predictable
impact on the environment. Alternative 4 is less effective than
Alternatives 10 and 17 because it would be more difficult to
keep water out of the trenches and to prevent contamination or
construction runoff water when installing the structural cap.
ImDlementabilitv
Alternative 5 would be the easiest to implement because it would
be a continuation of the present operation but with
improvements. Alternative 8 would be more difficult than
Alternative 5 because of the problems associated with repair of
the final cap over the period of trench subsidence. Both
Alternatives 5 and 8 would be easier to implement than the
alternatives involving grouting, dynamic compaction, or
structural concrete, all of which are more complicated
technologies. The dynamic compaction alternatives (4, 10 and
17) would be more easily implemented than the grouting
alternative (11). Nevertheless, dynamic compaction would
require pilot scale demonstrations of the suitability of this
technology to the MFDS.
Alternative 11 is the least implementable of the alternatives
evaluated at the MFDS. High production grouting (large volumes,
high injection rates, high pressures), although technically
feasible, has experienced difficulties at other similar sites.
Additionally, the scale to which it would be employed at the
MFDS is Buob greater than other sites where it has been
applied.~. Significant difficulties could be expected during
attempts to drive injection lances into the trenches. Grouting
would require additional research and testing at the MFDS due to
the complexities associated with grouting in trenches.
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Determination - Page 117
Cost
The present worth total cost of Alternative 5 depends on the
period assumed for interim maintenance and is a maximum when the
interim maintenance period equals zero years. Nevertheless,
comparing the maximum present worth total costs of Alternative 5
with those of other alternatives shows that Alternative 5 has
the lowest present worth total cost of any alternative
regardless of the length of the interim maintenance period.
Figure 16 illustrates the differences in total present worth for
four assumed discount rates over the projected subsidence
period.
Table 32 provides a cost breakdown for Alternative 5 and
provides cost estimates for Alternative 5 using four different
discount rates, 4%, 5%, 7%, and 10%. The $ 33,500,000 cost
estimate for Alternative 5 is based upon a 4% discount rate,
which is the most conservative rate of the four rates used in
the Feasibility Study. A 4% discount rate was used to compare
alternatives. The actual discount which will be used to
establish the MFDS trust fund has yet to be determined.
. Furthermore, the cost estimate for Alternative 5 assumes a 10%
contingency and installation of a North Cutoff Wall. The actual
contingency factor employed in the establishment of the MFDS
trust fund may be higher than 10%. The necessity of a
horizontal flow barrier and type of horizontal flow barrier
(i.e., North Cutoff Wall, Lateral Drain/Cutoff Wall, etc.) will
be determined during the Interim Maintenance Period; therefore,
the cost estimate for Alternative 5 is subject to change.
State AcceDtance
The Commonwealth generally endorses the selection of Alternative
5 (Natural Stabilization) as the remedy for the Maxey Flats
Disposal Site. The Commonwealth considers trench cover repair
and a horizontal flow barrier, if needed, to be integral
featurea.~~the remedy chosen for the site. The Commonwealth
rejects ~ha use of Alternative 10 and 17 (dynamic compaction)
for either a site demonstration or for total site remediation
due to potential release of contaminants into the environment
and uncertainties regarding dynamic compaction's effect on the
underlying geologic strata. The Commonwealth also rejects the
use of grouting (Alternative 11) for implementation at the MFDS
due to potential unacceptable releases to the environment,
implementability problems, and'required demonstration of this
technology ~rior to implementation. .
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'1eet 1 of 2
ALTERNATIVE-5: NATURAL STABILIZATION (50-ACRE CAP)
CAPITAL COSTS AND COST LAYOUT
============~=..aC...=2..RZC======..=~.=&==a==.=.=========a========:===========c=========================-======8====================================================
Year 1 Year 2 Year 3 Year 4 Interim Year 103 Year 104
1990 1991 1992 1993 Period 2092 2093
EstImated Totel
...........-..-...-.................-.-.....-..- ...---....-..--...
A. Construction Cost
Site Preparation Ind Support
1. Road Construction (Cut, Grlvel, ".,..c) $530,000 $0 $0 S430,000 $0 SO S100,000
2. Decon. Flcll fty(Equlp' t & Per80Me,U, $130,000 $0 SO S80,000 $0 SO S50,000
3. Utilities S50,000 SO SO no, 000 SO SO S20,OOO
4. Field Offices & Construction 'ence S200,000 SO $0 S120,000 SO SO S80,OOO
5. Topographic & Bkgd Radiation Survey S140,000 SO SO S70,000 SO SO S70,OOO
6. Ground Penetration Rldar Survey $150,000 $0 $0 S150,000 SO SO SO
7. Construction Erosion Control S200,000 SO SO S100,000 SO SO S100,000
8. Health Ind Safety S2,000,000 SO SO S1,000,000 S500,000 SO S500,000
9. OA/OC S1,080,000 SO SO S450,000 S250,000 SO S380,OOO
....-.... -........ ....-..--- .-.-.....-- ........ ---...-..--.
Sub-total S4,480,000 SO SO S2,430,000 S750,000 SO ",300,000
Specific Construction Activities
1. Leachate Removsl S1,252,000 SO $0 S1,252,OOO SO SO $0
2. Contaminated Liquid Handling and Disposal S4,079,000 SO SO S4,079,000 SO SO SO
3. Contemlnated 5011 Disposal $174,000 $0 $0 S174,000 SO SO SO
4. Existing Tank Leachate-Rem'l, Solld'n & Dlsp'l SO SO SO SO SO SO SO
5. Horizontal Flow Barrier (North Cutoff Well) S1,156,000 SO SO S1,156,000 SO SO SO
6. Additional BI~kflll SO SO SO SO SO so SO
7. Dynamic Compaction SO SO SO SO SO SO SO
8. Trench Grouting SO SO SO SO SO SO SO
9. Site Grldlng S160,000 SO SO S160,000 SO SO SO
10. Demol'n, Material Handling & Deeon. S740,000 SO $0 S450,000 SO SO S290,OOO
11. Leachata solfdlflcat'n/Add'l Disposal Trenches S4,706,000 SO SO S4, 706, 000 SO SO $0
12. Drainage Dftchel $889,000 SO SO SO $215,000 SO $674,000
13. Initial and Ffnal Closure Caps S17,489,000 SO SO SO S3, 449, 000 SO "4,040,000
14. Cap Erosion Control S1,445,000 SO SO SO S204,000 SO S 1,241,000
15. Long Tena Monitoring S691,000 SO SO SO 1626,000 SO S65,OOO
16. SecurIty Fence .120,000 SO SO 160,000 S6O,000 SO SO
-........... ............ ............ ............ .......
Sub-total $32,901,000 $0 $0 $12,037,000 $4,554,000 SO 116,310,000
Total Construction Cost S37,381,000 SO 10 S14,467,000 15,304,000 10 S17,610,OOO
B. Engineering and Management Cost
1. EngineerIng & Design (1) 12,990,480 SO S1 ,581 ,680 SO SO S1,408,800 10
2. ConstructIon Menagement (2) S1',214,300 SO SO S4,340,100 S1,591,200 SO S5,283,000
........oo........ oo ........... ................ .................. ................. ........... ................
Total Engineering & Management Cost S11,,201,,780 SO S1,581,680 S4,31,0,100 S1,591,200 S1,408,800 S5,283,000
s.:=:zz:==z:all: z::a:::=:::= a=8===S.1I ::====-==..:1 c:= =:11: ===::1. =======::1 ===========
Totel Ceplle' Cost $~1.~8~,780 SO S1,581,680 $18,807,100 S6,895,200 $1,1,08,800 S22,893.000
10\ Cont Ingency $~, 1~8,578 10 $158,168 S1,880,710 1689,520 S11,0,880 $2,289,300
.. .. .. .. -... ......oo ..........--- .........oo..... ................... ....OO".".OO"OO ............ ............ - .. ....-
lotel Copltel Cost wllh ContIngency $56,71,4,358 SO S1,739,848 120,687,810 S7,584,720 S1,549,680 S25, 182,300
=s:::::z:z:==== -------- ======::=== ----------- 1::==:::=::= ---------- ==========:
-------- ----------- ----------
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AlTERNATIVE-5: NATURAL STABILIZATION (50-ACRE CAP)
====:=====:se.................................C8sa8===.D.e=.=R=~C.=C===.~===================================-===S&:....===========-===================-
PRESENT WORTH CALCULATION. CAPITAL COSTS
AS5lmf1t ions:
1. Estimated Engineering and Design cost Is based on 81 of total construction
2. Estimated construction management cost Is based on 30 I of total construction
3. Scheduled construction period for Alternative 5 Is 20 months for Initial construction and 10 months
for final capping.
". .~
Discount Rates
41 51 7X 101
----------- ----..-.--- ---------.- ..--.....---
PII of Total Capital Coata 125,900,882 124,625,424 122,632,720 120,147,951
8R8.==_=ez. ...:e:::=:: ac=:..=::.. ..==::a..====
_...~_._.__._....._._._.__....-----_..-.-.._.-._._-_.-.-------------.--.-..-----------.----.--------------------.--...---.-.------------........-.........
PRESENT WORTH CALCULATION - 0 & M COSTS
AsslJl'4'tions:
1. Present worth of o&M coata I, based on perpetual annual maintenance and subsidence repair as required
2. All o&M costa Include Inflation at 01 per year-
3. 0&" beglna In December of Year 4 (1993).
4. Cost of yearly custodial malntenanca excluding subsidence repair Is 1385,000 for years 1 to 10, 1295,000 for years 11
to 100, 1240,000 years 101 to 110, and "90,000 years 111 onwards In perpetuity. In addition, 140,000 Is applied
every 5 years for the first 100 years for leachate pumping and solidification.
5. 0&" costs do-not Include taxes, Insurance and license fees.
Discount Rates
41 51 7X 10X
..----......... .-........... .......-....... .....-.-..--.
PII of Toul o&M Costs 110,097,549 17,692,612 14,924,075 12,921,415
m=====ca.. =:-.=8===-= a========:a ..:8=_==:1:
8.8..........................................""........"---...-.....---.............-..-------.....----------..-------..-....-.-...---........------.........-........-.----
PRESENT WORTH. TOTAL COST
PW of Total Cost
Discount Rates
41 51 7X 10X
.........-....... ..........-.. ......-....... ......-.....
$35,998,431 '32,318,036 '27,556,795 '23,069,366
2Z=:=====a: sa========= ==========a 1:8===:1:====
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-------
Determination - Page 121
Communitv Acceptance
Verbal comments received at the Proposed Plan public meeting,
held on June 13, 1991 in Wallingford, Kentucky, and on comments
submitted to EPA during the public comment period on the
Proposed Plan, indicate that the community favors Alternative 5,
Natural Stabilization, over the other alternatives considered.
However, the community urged inclusion of a number of features
in the Record of Decision and RD/RA Consent Decree. The
community's comments and suggestions, as well as EPA responses,
can be found in the Responsiveness Summary section of this
Record of Decision.
The community opposes the dynamic copaction alternative
(Alternatives 4, 10 and 17) for the MFDS, primarily because of
concerns over accelerated release of contaminants to the
environment during the compaction process. The community does
not favor the grouting alternative due to concern over potential
contaminant release from intact containers during the grout
injection process and uncertainties over the ability of grout to
adequately fill void spaces within the trenches.
9.3
Conclusions of the Comparative Analvsis Summary
Of the nine criteria described above, the differences between
the six remedial alternatives evaluated are not great, except
with respect to the following four criteria: 1) Implement-
ability; 2) Reduction of Toxicity, Mobility or Volume; 3) State
Acceptance, and 4) Community Acceptance. All remedial
alternatives provide for roughly the same degree of long-term
and short-term effectiveness. All remedial alternatives provide
for overall protection of human health and the environment and
all achieve ARARs. Although cost estimates differ amongst the
remedial alternatives, none differ by more than an order of
magnitude.
Therefore, Implementability, Reduction of Toxicity, Mobility or
Volume, . State Acceptance, and Community Acceptance weighed
heavily~n-favor of selection of Alternative 5. Alternative 5
is the least difficult remedy to implement, utilizing proven and
reliable technologies to achieve final remediation, while not
requiring time-consuming research and development prior to
implementation. It is less likely to result in container
rupture and, therefore, benefits from the added protection of
containers within the trenches. Both the State and Community
favor the Natural Stabilization technology.
-------
Determination - Page 122
SECTION 10.0 - THE SELECTED REMEDY
Based upon consideration of the requirements of CERCLA, the
detailed analysis of the alternatives, and public comments, EPA
has determined, and the Commonwealth agrees, that Alternative 5,
Natural Stabilization, is the most appropriate remedy for the
Maxey Flats Disposal Site.
The natural stabilization process at Maxey Flats will allow the
materials to subside naturally to a stable condition prior to
installation of a final engineered cap. It is not known how
long it will take for waste trenches to stabilize because of the
many physical and chemical variables involved and the limited
trench-specific information upon which predictions are based.
However, it has been estimated that this stabilization process
could potentially take 100 years before the final cap is
placed.
Stabilization of the trenches by natural subsidence over a
relatively long time period will virtually eliminate the
potential problem of future subsidence. expected with other
alternatives in which the trenches would be stabilized by
mechanical means and a final c.ap installed within a few years.
Therefore, the natural stabilization alternative will reduce the
redundancy of efforts necessary to construct and maintain the
final cap. Natural stabilization does not disrupt intact metal
containers such as 55-gallon drums and, therefore, provides an
extra measure of protection to prevent movement of radionuc1ides
to the hillsides. The other alternatives have the potential of
rupturing intact containers, thereby releasing radioactive
material immediately to the trenches. Additional benefits of
the natural stabilization alternative will be the opportunity
for continued data collection and analyses and the ability to
take advantage of technological advances during the subsidence
period.
Alternat;,i."..5 can be divided into the following four phases
which tQ9~~~er comprise the CERCLA remedial action for the MFDS:
.
.
.
.
Initial Closure Period (22 months)
Interim Maintenance Period (35 - 100 years)
Final Closure Period (10 months)
Custodial Maintenance Period (in perpetuity)
-------
Dete-rmination - Page 123
10.1 - Initial Closure Period
The initial closure period will consist of the design and
implementation of remedial activities appropriate to the early
stages of site remediation. An Interim Site Management Plan
will also be developed to define the maintenance and monitoring
tasks to be conducted during the subsequent interim maintenance
period.
The following remedial activities will be performed during the
initial closure period:
.
.
.
.
.
.
.
Baseline Topographic Surveys
Geophysical Surveys
Ground Water Monitoring
Ground Water Modeling
Trench Leachate Extraction and Solidification
Disposal of Solidified Leachate Into New Trenches On-Site
Demolition of Existing Buildings and Structures
With On-Site Disposal
Installation of an Initial Cap
Grading and Recontouring of the Initial Cap
to Enhance Surface Water Flow
Improvements to Site Drainage
Installation of Subsidence Monitors
Closure of Selected, Poorly Designed, Historical Wells
Monitoring, Maintenance, and Surveillance -
Procurement of a Buffer Zone Contiguous to the
Existing Site Property -
Posting and Repairing of Signs and Fences, Road Maintenance
Development of the Interim Site Management Plan
.
.
.
.
.
.
.
.
.
Baseline Topographic and Geophysical Surveys will be conducted
prior to design of the initial cap. Topographic surveys will be
performed prior to installation of the initial cap and following
construction of the cap to be used as a baseline survey for
subsiden~~'u~nitoring. A geophysical survey will enhance the
definit~_~f trench boundaries to ensure that the initial cap
will ad~ately cover the trenches.
Historical site monitoring data, the Commonwealth's site
database, and ground water models will be used to determine the
. appropriate areal extent of the initial cap, to evaluate the
need for a horizontal ground water flow barrier, and to develop
an effective ground water monitoring plan for the Interim
Maintenance and Custodial Maintenance Periods. The ground water
monitoring program will involve installation of new monitoring
wells, as appropriate, in the alluvium of the surrounding stream
valleys, and in other areas as required, to ensure compliance
with drinking water standards and to achieve RCRA monitoring
requirements.
-------
Determination - Page 124
Trenches will be dewatered to help prevent the migration of
contaminants by ground water flow. A trench dewatering test
program will be conducted either during the design phase or
during initial remedial activities to provide information on the
most effective design of the dewatering program, to determine
the need for new sumps, and to provide an estimate of the
duration of the dewatering program.
Leachate pumped from the trenches will be extracted
simultaneously from multiple trenches and batched prior to
solidification. Additional sumps will be added in select
trenches with significant quantities of leachate in order to
facilitate the dewatering of trenches. Trench dewatering is the
most time-consuming component of the Initial Closure Period. A
minimum of nine months will be required to dewater the trenches.
Once batched, the leachate will undergo testing for NRC
classification purposes. Once classified, the leachate will be
solidified using an NRC-approved mix. The waste form will
likely be in block form, provided an acceptable leachability
index and cumulative fraction leached can be achieved. However,
high activity leachate will be required to be placed in a
primary container and solidified. The solidified leachate will
also be designed to achieve a sufficient minimum compressive
strength. The objectives of the leachate solidification will be
to produce a solid, physically stable form of the leachate,
thereby minimizing the mobility of the contamination within the
trenches. During the leachate solidification operations,
external exposure to ionizing radiation will be kept as low as
reasonably achievable by using engineering safeguards, such as
shielding, and administrative safeguards such as detailed health
and safety procedures for all operations. Internal exposure to
radioactivity should be insignificant, since the systems that
handle radioactivity would be designed to minimize leakage.
The solidified leachate will then be placed into new disposal
trenches~:-9~-:site and within (or in close proximity to) the
current ~e~tricted Area. Grout will be used in the newly
constructed" .trenches to fill the void spaces between the
solidification forms, in effect, creating a monolith within the
trench. Bach new disposal trench will, at a minimum, include a
sump and a synthetic liner (unless it is later determined by EPA
and the Commonwealth that use of a liner is inappropriate).
Non-functional and unstable buildings and structures will be
dismantled, decommissioned and 'buried in a trench on-site
-------
I-
I
Determination - Page 125
during the Initial Closure Period. Such buildings and
structures will probably include: the storage building,
evaporator building, garage building, radiological control
building, the sewage treatment plant, and tank farm buildings.
Those buildings necessary to the management and maintenance of
the site will be moved to a new location that will not impede
remedial activities. Figure 18 is a typical construction
planning drawing that may be employed during the Initial Closure
Period.
An initial cap, consisting of a soil layer of compacted clay
(averaging 21 inches thick) and covered with a synthetic liner,
will be installed toward the end of the Initial Closure Period.
Soil will be added to the site and graded and compacted in
preparation for the installation of the synthetic cover over the
trench disposal area. Conceptual cross-sections of both the
initial cap and the final cap are presented in Figure 19. The
areal extent of the interim cover will be based upon geophysical
surveys, ground water modelling and other parameters evaluated
during design. It has been estimated that the interim cap will
cover approximately 40 to 50 acres. Fugitive dust problems
during earth-moving operations will- be controlled by using water
or other dust suppressants. Kentucky Soil and Water
Conservation requirements for controlling soil erosion will be
met by designing and locating technologies and activities to
minimize potential erosion.
The surface will be graded to design specifications to allow for
adequate drainage and to minimize surface water velocities and
consequent erosion. Lined drainage ditches will be incorporated
in the trench cap to channel the surface water runoff to the
three existing discharge basins located along the periphery of
the trench disposal area. Improvements will also be made to the
existing site drainage channels on the hillslopes. These
erosion protection measures could include, but will not
necessarily be limited to, stabilization of the drainage
channels where necessary by such measures as rock rip-rap or
gabions-~()::reduce the velocity of flow. Additional drainage
channel~:'-in:;the vicinity of the site may be added if found to be
necessary to control, and more equitably distribute, the
anticipated increased rates of surface water runoff. Because of
the high peak discharge volumes resulting from the initial cap,
the capacity of the retention ponds will be increased to improve
control of stormwater runoff. Approval of the initial cap
design will be contingent upon the ability of the surface water
controls to adequately maintaia rates of surface water runoff
throughout the anticipated duration of the Interim Maintenance
Period.
-------
FIGURE 18
Determination - Page 126
^
OJl
M»*8V FLATSfSttfePONT
MAXtY FIATS Sill HI/FS
EBASCO SlWVICtS INCOHPOHAUO
CONSTRUCTION PLANNING
DRAWING
HOUHt t 1
-------
FIGURE 19
01
00
eg
2-
C
O
CO
c
•V*
B
u
41
O
THICKNESS
IFEETJ
VARIABLE
VARIABLE
r-0,7
30-40MIL
SYNTHETIC
COVER
INITIAL CLOSURE CAP
VARIABLE
FINAL CLOSURE CAP
EXPLANATION
30TO4OMIL SYNTHETIC COVER
TOPSOIL LAYiR WITH VEGETATIVE
COVER
SILTYSAND
GEOTEXTILE FABRIC
CRUSHED ROCK
80 MIL SYNTHETIC LINER
FJ-J^
I™
CLAY LAYER
(PERMEABILITY < 1 * tO~
COMPACTED SOIL LAYER
EXISTING TRENCH SOIL COVER
TRENCH WITH RANDOM!. Y PLACED
WASTE CONTAINERS
NOT TO SCALE
MAXEY PLATS FS REPOPT
MAXEY FLATS SITE RI/FS
EBASCO SERVICES INCORPORATED
ALTERNATIVE 5
NATURAL STABILIZATION
040191
FIGURE 4-3
-------
Determination - Page 128
Subsidence monitors will be installed on the initial cap and on
natural soils in the vicinity of the Restricted Area as a method
of determining when the trenches have stabilized to an
acceptable degree and final cap installation can begin.
A limited number of existing, poorly designed, wells (i.e.,
E-Wells) could potentially allow contaminants in ground water to
migrate downward into the lower geologic units and will,
therefore, be decommissioned and sealed. Existing sumps and
wells (i.e., UE, UF UG, UK, etc.) that are deemed beneficial to
the leachate extraction process, as well as those necessary for
trench monitoring, will not be decommissioned.
Water monitoring equipment, as part of an Infiltration
Monitoring System, will be installed in trenches, under the cap
and within wells, to detect potential accumulation of leachate
in trenches. Vibrating wire piezometers, such as the one
illustrated in Figure 20, will be installed in riser pipes after
construction of the initial cap. Riser pipes will be installed
during cap construction and will be used to extend the
monitoring wells through the cap. Water level data from the
trenches and wells will be collected by data logging equipment
located at the site. This data, in conjunction with other
information, will be used to assess the degree to which
infiltration is occurring, if any.
The monitoring program developed for the MFDS will, at a
minimum, include the following objectives:
. Demonstration of compliance with the applicable or relevant
and appropriate regulations, environmental standards, and other
operational limits.
. Assessment of the actual or potential exposure of man to
radioactive materials or chemical constituents in the
environment.
. Detj~ti~n of any possible long-term changes or trends in
the env~~~ent resulting from the site.
. Assessment of the performance (adequacy) of design features
that limit the release of radioactive materials to the
. environment.
R~dionuclide and chemical constituent testing of ground water,
surface water, soil, sediment and air will be performed, as
appropriate and on a routine basis, to ensure that the remedy
-------
Determination - Page 129
FIGURE 20
SIGNAL CABLE TO DATA LOGGER
CLOSURE CAP
TRENCH
EXISTING TRENCH SOIL COVER
VIBRATING WIRE PIEZOMETER
(SEE DETAIL Al
SIGNAL CABLE
JUNCTION BOX
2 INCH
DIAMETER
PERFORATED
PIPE
PIEZOMETER
DETAIL A
MAXEY FLATS PS
MAXEY FLATS SITE RI/FS
EBASCO SERVICES INCORPORATED
VIBRATING WIRE PIEZOMETER
THROUGH TRENCH SUMPS
FIGURE Ell
-------
, --
Determination - Page 130
for the MFDS is achieving all ARARs and continues to be
protective of human health and the environment. Monitoring of
leachate levels in trenches, subsidence monitoring and erosion
and siltation monitoring will be routinely conducted. A program
will be established to assess and track the impact of site
remediation on local wildlife and vegetation and to confirm the
assumptions and conclusions of the MFDS risk assessment. These
monitoring programs will be established during the Initial
Closure Period (as specified in the Interim Site Management
Plan) and continued through the Interim Maintenance Period and
on into the Custodial Maintenance Period.
A buffer zone, adjacent to the existing site property
boundaries, will be acquired. The primary purpose of a buffer
zone is to protect environmentally sensitive areas such as the
hillslopes from detrimental activities such as logging. Without
control of activities on the hillslopes, increased erosion due
to deforestation could severely affect the integrity of the
remedy.
The buffer zone will not extend the current licensed site
property boundary, although control 'over the property would
likely be in the hands of the Commonwealth of Kentucky.
Moreover, the points of compliance for ARARs will not be
extended by procurement of the buffer zone. Monitoring of
streams, ground water and other media will be conducted in the
buffer zone and other areas deemed necessary to assure that the
selected remedy achieves ARARs. Indeed, the secondary purpose
of the buffer zone is to ensure unrestricted, long-term access
to areas necessary for full and effective monitoring.
At a minimum, the buffer zone will extend from the current site
property boundary to Drip Springs, No Name, and Rock Lick Creeks
to the west, east, and southwest of the site, respectively. The
tentatively identified Buffer Zone, illustrated in Figure 21, is
a conceptual delineation of the minimum boundary of the buffer
zone.
.;...;=':~ '-, .'
:~::. :.. -:.' .-
Signs wi;.1:"1:ie posted warning potential trespassers of the
presence~:::.of"8ite contaminants. Fences will be constructed,
repaired and/or re-aligned as needed to prevent unauthorized
access to the capped trench disposal area, construction areas
established during the Initial Closure Period, and other areas
deem9d inappropriate for access. Access to the MFDS from
Interstate 64 is via State Road 32 to County Road 1895, which
runs to the entrance of the MFDS. County Road 1895 is a
two-lane paved road suitable for the maximum legal load allowed
-------
Cu
I
l_
OJ
4J
1)
Q
RINGOS MILLS O.B MILES
'/r
r ,
MFDS RESTRICTED
AREA
MFDS PROPERTY
BOUNDARY
PROPOSED BUFFER
ZONE
1AP PRODUCED BY EBASCO SERVICES INCORPORATED AND .A3:
FOR THIS REPORT BY BOOZ, ALLEN & HAMILTON, nc
MAXEY FLATS DISPOSAL SITE
PROPOSED BUFFER ZONE MAP
MAP 6
22
-------
Determination - Page 132
by Kentucky's Department of Transportation and appears to be in
good condition. Well in advance of construction activities, the
need to upgrade County Road 1895 will be discussed with Fleming
County officials. Should it be determined that site activities
are having a detrimental effect on County Road 1895, the
authority(ies) responsible for remediation of the MFDS will be
responsible for funding such repairs.
A comprehensive Interim Site Management Plan will be developed
during the Initial Closure Period to define the maintenance and
monitoring tasks to be conducted during the Interim Maintenance
Period.
10.2
Interim Maintenance Period
Upon installation of the initial cap, the Interim Maintenance
Period will commence. The primary objective of the Interim
Maintenance Period is to let the trenches stabilize by natural
subsidence. The Interim Site Management Plan will provide the
basis for work activities during the interim maintenance
period. During this period, the initial cap will continue to be
maintained to prevent infiltration of water into the trenches,
maintenance of the site will continue, and the site will be
monitored by an enhanced monitoring/surveillance program.
During the Interim Maintenance Period, the following activities
will be performed as prescribed by the Interim Site Management
Plan:
.
.
.
periodic Topographic Surveys and Subsidence Monitoring
Initial Cap Maintenance
Continuing Assessment of the Adequacy of the Initial
Cap, Surface Water Control Measures
and Erosion Control Measures
Improvements to Site Drainage Features, As Needed
Trench Leachate Management and Monitoring
Mo~toring, Maintenance, and Surveillance
En~c.~ Ground Water Monitoring
In~allation of a Horizontal Flow Barrier, As Required
Five-Year Reviews
.
.
.
.
.
.
Topographic surveys and elevation surveys of the subsidence
monitors will be conducted routinely to evaluate subsidence.
Settlement plates and slope inclinometers (and/or other
subsidence monitoring instruments) will be installed at the MFDS
to measure vertical movement, tilt or subsidence of the trench
contents and trench cap over time. This information will form a
database to. be used to assess cap stability and the degree to
which trench subsidence has occurred.
-------
Dete.rmination - Page 133
The initial cap will be routinely inspected to ensure that it
has not ~ailed and it is effectively controlling surface water
runoff. As needed, the cap will be repaired and the synthetic
liner replaced in accordance with the Interim Site Management
Plan. Currently, it is anticipated that the synthetic liner
will require replacement at 20-25 year intervals. Liner
replacement will be performed in response to liner condition and
the manufacturer's warranty and specifications. The specific
liner type will be determined during development of the Interim
Site Management Plan; however, the liner will be of. the type to
require replacement no more often that the afore-mentioned 20-25
year interval. The drainage ditches and retention ponds will
also be cleaned and maintained as needed.' Erosion damage to the
cap and drainage systems will be repaired as needed.
The Infiltration Monitoring System, installed during the Initial
Closure Period, will detect the accumulation of leachate in the
trenches and provide a warning if leachate begins to accumulate
in the trenches. This monitoring system will be used as a
supplement to the Commonwealth's current trench leachate
monitoring program. Measures could then be taken to eliminate
the cause of the infiltration. If trench recharge is occurring,
the leachate management plan, developed as part of the Interim
Site Management Plan, will be implemented to remove, solidify,
and dispose of the leachate. The data from the monitoring and
leachate extraction program will be used to adjust the frequency
of inspections, data collection, sample analyses, and planned
leachate pumping and solidification.
Trench leachate recharge should be kept to a minimum, once the
disposal trenches have been pumped to the extent practicable and
the initial cap has been placed over the disposal area.
However, should conditions warrant re-initiation of a trench
leachate extraction program, trench leachate will be solidified
and disposed in on-site trenches. On-site activities during the
Interim Maintenance Period may generate additional wastes
requiri~9-disposal. Liquids will be temporarily stored until
sufficiei\~~'~antities have accumulated to warrant resumption of
solidif~.tion processes. Once liquids have been solidified, a
new dis~sal trench will be constructed to dispose of the
solidified liquids and any solids generated during on-site
activities.
Site monitoring activities will be performed as defined in the
Interim Site Management Plan and established during the Initial
Closure Period. Site maintenance activities will include
custodial care such as grass cutting, ditch cleaning, and fence
-------
Determination - Page 134
repairing. On a less frequent basis, repairs will be made to
the erosion control system, the initial cap, and monitoring
instruments. Additionally surveillance activities will be
performed on a routine basis to inspect the site. Maintenance
and monitoring activities will be conducted in compliance with
the Federal and Kentucky Licensing Requirements for Land
Disposal of Radioactive Waste.
For those remedial actions that allow hazardous substances to
remain on-site, Section 121(c) of CERCLA requires EPA to conduct
a review of the remedy within five years after initiation of
remedial action and at least once every five years thereafter.
The purpose of this review is to evaluate the remedy's
performance - to ensure that the remedy has achieved, or will
achieve, the remedial action objectives set forth in the Record
of Decision and that it continues to be protective of human
health and the environment. Additionally, the Commonwealth will
continue an environmental program to evaluate all aspects of the
remediation during the five year review periods.
During any of the five year reviews, or at any point between the
five year reviews, if the remedy is' not meeting the defined
remedial action objectives, a more detailed sampling program
will be undertaken to determine the cause of the failure.
Specifically, the reviews may focus on, among other things, the
selected remedy's ability to prevent entry of water into the
disposal trenches, to mitigate erosion to the extent
practicable, and to minimize migration of radionuclides and
chemicals.
Should site monitoring and surveillance demonstrate a failure of
the remedy to achieve ARARs or remedial action objectives (e.g.,
alluvial ground water monitoring indicates Maximum Concentration
Limits have been exceeded), the appropriate remedial steps will
be taken, such as notification of regulatory agencies, public
safeguards, repair of the remedial technology, or cleanup of the
enviro~~~tal medium.
.-:.. .. .
The uncertaInties of hydrogeologic flow conditions at the MFDS
(as discussed in the RI Report for the MFDS and Section 5.1.2 -
Geoloav and Ground Water of this document), as well as the
uncertainties related to the impact of the leachate extraction
operations on the hydrogeologic flow conditions, necessitate
further evaluation of data in order to assess the necessity and
likely effectiveness of a horizontal flow barrier. Sufficient
data should be available from the trench dewatering program,
information contained in the Commonwealth's historical leachate
level database, the Infiltration Monitoring System, ground water
-------
Determination - Page 135
monitoring, and the ground water modeling program to determine
the necessity of a horizontal flow barrier before or in
conjunction with the first five year review. If statistical
analysis of trench data (to include water level data, regression
slopes, etc.) indicates that lateral recharge of the disposal
trenches is occurring, a horizontal flow barrier will be
installed to curtail ground water recharge of the disposal
trenches. The necessity, location, depth, and extent of this
horizontal flow barrier will be determined through ground water
modeling and review of historical site monitoring data.
Two types of horizontal flow barriers were evaluated in the
Feasibility Study, as discussed in Section 7.2.2.2 (Horizontal
Flow Barriers of this document), and illustrated in Figures 22
through 24; a north cutoff wall and a lateral drain/cutoff
wall. The type of horizontal flow barrier installed at the site
will be one of the two described barriers or another design
determined to be sufficient for prevention of lateral
infiltration.
The decisions as to whether and what type of horizontal flow
barrier to construct will be made by EPA, in consultation with
th~ Commonwealth of Kentucky.
10.3
Final Closure Period
The end of the Interim Maintenance Period and the beginning of
the Final Closure Period is defined as the time when subsidence
of the trenches has nearly ceased and final cap installation
can begin. The criteria for determining when this time has come
could include such factors as acceptable void fraction, defined
rate of minimal subsidence, defined backfilling rate to maintain
design grade, etc. EPA, in consultation with the Commonwealth,
will determine the acceptable subsidence criteria during
remedial design and/or development of the Interim Site
Management Plan.
The following activities will be undertaken during the Final
Closure Period:
_. .
.
.
.
Waste Burial
Installation Of
Installation Of
Features
Installation Of
Final Cap
Permanent Surface Water Control
.
Surface Monuments
Prior to installation of the final cap, contaminated materials
at the site will be buried in a new disposal trench on-site.
These materials could include solidified leachate, leachate
storage tanks, and on-site buildings which will be demolished
during final remediation.
-------
Determination - Page l36
LOWE R
MARKER
BED
HENLEY
BED
A
FIGURE 22
A'
VERTICAL INFIL TRA TlON BARRIER
LOWE R
NANCY
MEMBER
40 SERIES
TRENCHES
LOWER
NANCY
MEMBER
UPPER FARMERS MEMBER
----
LOWER FARMERS MEMBER
SUNBURY SHALE
BEDFORD SHALE
AND OHIO SHALE
COLLECTION WELLS
GROUNDWATER
CUTOFF WALL
COMPACTED CLAY
OR SLURRY WALL
GROUT
INJECTION WELL
DIAGRAMA TIC CROSS SECTION A - A'
. .
'. -
~'.:;...'..:
LOCA TlON OF CROSS SECTION
SHOWN ON FIGURE 3-2
MAXEYFLATSFSREP~C'
MAXEY FLATS SITE RI/FS
EBASCO SERVICES INCO~P:CATE!J
GROUNDWATER CUTOFF WALL
AND COLLECTION WELLS FOR
40 SERIES TRENCHES
F IGiJRE 34
-------
Determination - Page 137
FIGURE 23
CLAY/SOIL BACKFILL
M.i':\WW~:wt:!'h~:::- LOWER MI- RKER BEO
GRADED GRAVEL
OR CRUSHED ROCK
LIQUIDS IN THE PE",FORATED PIPE WILL
DRAIN TO CDLLECilQN MANHOLE (SEE
DETAIL BELOW) ANO PUMPED INTO A
STORAGE TANK FOR TREATMENT AND
DISPOSAL.
DETAIL 1
TO STORAGE TANK
LATERAL DRAIN PIPE
SUMP PUMP
COLLECTION MANHOLES WILL BE SPACED
APPROXIMATELY .ioe FEET APART.
5 FT. DIAMETER MANHOLE
01 RECTION oeL '., .
CONTAMINATE_~'-:.-.
WATER flOW' ." - .
DETAIL OF COLLECTION MANHOLE
MAXEY FLATS FS REPCRT
MAXEY FLATS SITE RI/FS
EBASCO SERVICES INca"PORATED
LATERAL DRAIN
FIGURE 3.31
-------
Determination - Page 138
a-- ..• • ..•-- , s •)-/
/ -"^^r^&.^
UIAC.HAMA! 1C CROSS SiCTION A A
(SEE FIGUNI 341
EXPLANATION
+ THIHCN SUM?
I I AffHDHIUAll BOUNDARY Of
I I I HI HIM
ft NCI I INI ANO aOUNOAH Y Of
HtSIHH TtUAHlA
^^^ BUILDING
•••^•^ H'lHAi OH AIM
m « <•• (.HOtlHlMATlH CUIOff WALL
HAMIV * LAnrSNfrOIK
HAXEV FLATS (ITI RI/FS
CBASCO SENVICfS INCOHPOH A 11 D
HORIZONTAL FLOW BARRIER
noum »
O
1
-------
,-
Det~rmination - Page 139
Because the selected remedy involves disposal of a RCRA listed
hazardous waste, the RCRA Subtitle C closure standards are
applicable to the MFDS. Consequently, the final cap will be
designed and constructed to promote drainage, minimize erosion
of the covsr, and provide long-term minimization of migration of
liquids. The design criteria and allowable soil loss for the
final cap will conform, at a minimum, to the standards
established in EPA's "Cover for uncontrolled Hazardous Waste
Sites", EPA/540/2 - 85/002 (USEPA, 1985).
The trench disposal area and appropriate areas contiguous
thereto will be covered by an engineered soil cap with a
synthetic liner. It is expected that this cap, as described in
Table 33, will consist of (from top to bottom) an initial layer
of compacted soil placed over the existing trench cover, a
two-foot thick clay layer, an 80 mil (or sufficiently similar)
thick synthetic liner, a geotextile fabric layer, a
one-foot-thick drainage layer, a geotextile fabric layer,
two-foot thick soil layer supporting a vegetative cover.,
compacted clay layer will have a permeability of 1 x 10-
feet/year) or less.
The final cap will be constructed primarily of naturally
occurring materials that are stable in the Maxey Flats
environment. To provide additional protection against vertical
infiltration of water and to provide additional durability
during the first few decades following installation, some
synthetic materials will be integrated within the multi-layered
structure of the final. cap. The engineered soil cap with
synthetic liner, when installed, will provide an effective
barrier against vertical infiltration of water. The cap should
last for a long period of time if (a) repairs are performed
promptly, as needed, during the first few decades following
installation, and (b) minor custodial maintenance is provided.
The cap will direct percolating water away from the disposed
waste by drainage layers and its sloped design. The multi-layer
constru~t~on will resist degradation through geological
process~:.:arid biotic activity. Additionally, the seeded topsoil
layer will" enhance erosion control. Erosion control will be an
inteqral::'coDiponent of the final cap design. Cap erosion,
hillslope erosion, and rates of surface water runoff to
downslope areas will be considered during final cap design.
and a
The
(0.1
Effective, permanent surface water control systems will also be
installed to limit infiltration and control surface water runoff
and minimize hillslope and cap 'erosion to the extent
J
-------
Determination - Page 140
TABLE 34
FINAL CAP COMPONENTS
- Vegetative Cover:
Erosion control
- Geotextile Fabric: This fabric beneath the upper soil layer
will keep soil fines from settling in the drainage layer and,
thus, reducing the effectiveness of the drainage layer
- Drainage Layer: This will consist of suita~ly graded crushed
rock with a minimum permeability of 1 x 10- cm/sec; will
provide a stable drainage path to erosion control drains
- Geotextile Fabric: This fabric between the drainage layer
and synthetic liner will protect the liner from puncture
during installation of the drainage layer
- Synthetic Liner: will provide a backup to the clay
infiltration barrier for the purpose of minimizing
infiltration of water to the disposal trenches
- Two-Foot-Thick Clay Lay,r: will provide a barrier with a
permeability of 1 x 10- cm/sec or less.
- Initial Soil Layer: will provide support and establish the
desired design grade for subsequent layers
-, -- .
:~kŁ( ::--.
::~~~'- ."'
-------
Determination - Page 141
practicable. After the final cap is constructed, channels and
drainage ditches carrying storm' water runoff from the site will
be improved to ensure stability for runoff events up to that
which would result from a 100-year, 24-hour storm. It is
expected that a significant amount of research data and
information on new technologies will be developed throughout the
Interim Maintenance Period. Thus, the design of the final cap
and surface water control features may reflect theBe
technological advances.
The monitoring and surveillance program, established in the
Initial Closure Period, will continue to ensure compliance with
state and federal regulations, to ensure the remedy is meeting
the remedial action objectives, and to ensure that the remedy
continues to provide protection of human health and the
environment. Surface monuments will be erected at the site to
notify persons of the presence of site contaminants and the
dangers posed by site contaminants if the site is disturbed.
10.4
Custodial Maintenance Period
After the final cap has been constructed, the Custodial
Maintenance Period will begin. The following activities will be
performed during the Custodial Maintenance Period:
.
.
Monitoring and Surveillance
Five Year Reviews
The monitoring and surveillance program will continue to be
implemented at the site. The frequency of monitoring activities
described for the Interim Maintenance Period will likely be
reduced during the Custodial Maintenance Period due to the
presumed reduction of water infiltration into the trenches
(i.e., reduced contaminant mobility) and reduced radionuclide
activity. Site monitoring and surveillance will be carried out
in perpetuity. Maintenance activities will be carried out, as
necess&r}';"to preserve the integrity of the remedy.
The Cusf9di~l Maintenance Period will initiate the institutional
control ~period which must be maintained for at least 100 years
following completion of the site closure as required by 902 KAR
100:022 and 10 CFR part 61 for all low level radioactive waste
disposal sites. In addition, the perpetual maintenance fund
will ensure that institutional control activities, including
fencing and other activities to control access to the MFDS,
periodic surveillance, custodial care, and filing of notices,
survey plats, and deed restrictions with the appropriate
authorities, will accomplish the goal of preventing inadvertent
intrusion onto the MFDS and providing of custodial care in
perpetuity. The fund will also provide for collection and
analysis of samples and data.
-------
Determination - Page 142
SECTION 11.0 - STATUTORY DETERMINATIONS
Under its legal authorities, the U.S. EPA's primary responsibility
at Superfund sites is to undertake remedial actions that achieve
adequate protection of human health and the environment. In
addition, Section 121 of CERCLA establishes several other
statutory requirements and preferences. One of the requirements
specifies that, when complete, the selected remedial action for
this site must comply with applicable or relevant and appropriate
standards established under Federal and State environmental laws
unless a statutory waiver is justified. The selected remedy also
must be cost effective and must utilize permanent solutions and
alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. Finally, the
statute includes a preference for remedies that employ treatment
technologies that permanently and significantly reduce the volume,
toxicity, or mobility of hazardous wastes as their principal
element. The following sections discuss how the selected remedy
meets these statutory requirements.
11.1
Protection of Human Health and the Environment
Protection of human health and" the environment will be achieved
through the treatment, containment, engineering and institutional
control components of the selected remedy.
Based upon the site risk assessment, unless remedial action is
taken, exposure to drinking water, surface water, soil and
sediments at, and in close proximity to, the site in the future
would pose an unacceptable risk to human health. The risk
assessment estimates that the risk from all combined on-site
pathways at the MFDS, if no action is taken, could approach 1
(i.e., one additional case of fatal cancer for each person who
would reside on-site). The risk assessment estimates that the
risk from all combined off-site ~athways at the MFDS, if no action
is taken, could approach 6 x 10- (i.e., six additional cases of
fatal c~~e~ for every 100 persons engaging in the off-site
exposur~:pathways as described in Section 6 of this document).
The4sel~te~ remedy will reduce these iisks to a risk of 1 x
10- or -Ie... EPA deems a risk of 10- to be generally
protective of human health and the environment.
The extraction, solidification, and re-disposal of trench leachate
will significantly reduce the mobility of radionuclides. Initial
and final caps will significantly reduce the amount of vertical
infiltration into the disposal'trenches, thereby minimizing the
production of leachate, thereby minimizing the migration of site
contaminants into the environment. Surface water drainage
improvements will help maintain the integrity of the remedy by
-------
Determination - Page 143
controlling the rate of site erosion. Site monitoring and
maintenance and institutional controls, funded and conducted in
perpetuity, will prevent unintended use of the site, minimize the
amount of exposure to site contaminants, and maintain the
integrity of the remedy.
There are no short-term threats associated with the selected
remedy that cannot be readily controlled. In addition, no adverse
cross-media impacts are expected from the remedy.
11.2
ComDliance With ARARs
The selected remedy will comply with all.applicable or relevant
and appropriate requirements (ARARs) except for the RCRA Land
Disposal Restrictions which are being waived pursuant to CERCLA
Section 121(d). ARARs identified for the MFDS are presented in
Section 8.0 of this document.
11.3
Cost Effectiveness
The selected
to its cost.
alternatives
exception of
remedy provides overall effectiveness in proportion
Alternative 5 is the least costly of the seven
that underwent a detailed analysis, with the
the No Action alternative.
11.4 Utilization of Permanent Solutions and Alternative Treatment
Technoloqies or Resource Recoverv Technoloqies to the
Maximum Extent Practicable and Statutory Preference for Treatment
as a PrinciDle Element
EPA and the Commonwealth of Kentucky have determined that the
selected remedy represents the maximum extent to which permanent
solutions and treatment technologies can be utilized in a
cost-effective manner for the final source control remedy at the
Maxey Flats Disposal Site. Of the alternatives evaluated and
presented in this decision document, EPA and the Commonwealth have
determin,d that this selected remedy provides the best balance of
tradeof~':in: terms of long-term effectiveness and permanence,
reducti~~i~ toxicity, mobility, or volume achieved through
treatment'~ short-term effectiveness, implementability, cost, also
considering the statutory preference for treatment as a principal
element and considering State and community acceptance.
While the selected remedy does not reduce the volume of waste
present at the site, or offer treatment as a principal element,
Alternative 5 does address the.primary threat associated with the
site; that of the migration of contaminated leachate into the
environment. The selected remedy will achieve a reduction of the
mobility of the contaminated leachate through solidification and
-------
Determination - Page 144
prevention of the generation of new leachate, and will minimize
erosion to the extent practicable to preserve the integrity of the
remedy. The initial and final caps, surface water control
features, monitoring and maintenance components, and other
engineering features, as well as institutional controls will
reduce or control site risks to the extent practicable.
Treatment of site wastes is not practicable at the MFDS due to the
nature and volume of waste involved. Excavation and off-site
disposal are not feasible at the MFDS due to the lack of
facilities that could. accept the volume and activity of the waste
present at the MFDS and the greater risk to human health and the
environment-which would be associated with such activities.
Furthermore, excavation of site wastes would not- achieve the
Commonwealth's applicable requirement - 902 RAft 100:015, which
requires exposures to be kept to "As Low As Reasonably
Achievable" .
;'7 .
.: ~. .
.'
-------
APPENDIX B
NUMERIC CRITERIA FOR
APPLICABLE OR . RELEVANT AND APPROPRIATE REQUIREMENTS
-------
R2LRVANT AND APPROPRIATE CONTAMINANT-SPECIFIC
R20UIREMENTS FOR THE MAXEY FLATS DISPOSAL SITE
. SELECTED REMEDY
Clean Water Act - Water Oualitv Criteria tua/l1
Aauatic Life' Human Healtha
Acute Chronic
Chemical (l-Hour Averaae) t4-Dav Averaae) Fish Only
Nickel 790/1400/2500d 88/160/280e 100
.Vinyl Chloride b b 5246c
Benzene 5300f b 400..0c
Chloroform 28,900f 1240f 157.0c
1,2-dichloroethane 118,000f 20,000f 2430.0c
Trichloroethylene 45,000f 21,900f 807.0c
Arsenic b b .17 5c
.,ead 34/82/200d 1.3/3.2/7.7. b
bis(2-ethylhexyl)
phthalat.. 940 3 b
Chlorobenzene 250f 50f 488
Toluene 17,500f b 424,000
Note.:
a) . Assumed,intaka i. 6.5 grama of fish per day for a 70-year lifetL~e.
EPA a88ume. an adult body weight is 70 kilogr&m8. .
b) Clean Wat.r Act - Water Quality Criteria are not available for this
contaminant.
c) The value wa~ calculated assuming ri8k level. of 10-5 per lifeti~e.
. d) . Becau.. th.'toxicity of nickel i. dependant on hardness, EP~'s aC'J-:'e
criterion i.' .xpre..ed a. a formula: e(0.8460 [In (hardne8s)]+ 3.36~21
The criteria above were calculated using thi8 formula, assuminq hard~ess
equal to 50, 100, and'200 mg/l as CaC03.
e) , ,EPA's formul~ for calculating chronic criteria i8:
eCO.S460[ln (hardne..)]+ 1.1645). T~e criteria above were calculated
using tbi. formula, a..uming hardnes. equal to 50, 100, and 200 mg/~ H
~aC03.
.) Lowe.t ob..rved effect level.
-------
"
TAIU A-'
""'I~ E ACTICJI-SP€CIFtC AIID CCIITMIIWfT-SP€CIFtc: IRUI~
Fat talEDlAL ALTEUATI'4!S AT Mm FUT) ,
PlutoniUl-238
RADIOlOGICAL COITMI.AIITS
ICy Aver... 18dIcn.cl.ic8 c:.anc.ntratfCINl
(uCi/lIIl)
(902 (AI 100:025)
hbleZ T8ble ,,3
Air WIIter A'r \Ulter
1 x 10.1 (S) 4 1 It 10.5 3 It 10"11 3 II: 10.7
5 x 10.1 (I) , 1 ,. 10"3 2 x 10"10 10 I( 10.'
2 x 10.Uh(S) 1 II: 10.4 7 X 10.14 5 I( 10-6
3 I( 10"11 (I) a I( 10"4 1 x 10:,12 3 x 10-'
3 I( 10"11 (5) 5 I( 10"' 1 I( 10.2 2 I( .10.6
3 I( 10.11 (I) 1 I( 10.3 1 II: 10.2 10 II 10.'
6 I( 10-12 (S) 1 II: 10-4 ' 2 I( 10"13
10 II 10.6
1 I( 10.10 (I) a I( 10.4 10 I( 10-12 3 I( 10-'
3 I( 10.7 ($) 1 I( 10"3 1 ,. 10"8 5 I( 10-'
9 ,. 10-1 (I) 1 I( 10.3 3 ,. 10-10 3 II 10.'
6 I( 10"8 (5) 10 I( 10.4 2 I( 10.1 2 I( 10-'
1 It 10-8 (I) 1 It 10.3 5 It 10.10 10 x 10"
10 It 10.1 ,($) Z I( 10.1 1 It 10-7 a It 10.0;,
5 x 10.' (SI.O)I 1 x 10.'
5 x 10.1 (S) 1 x 10.1 Z x 10:; 3 x 10-3
5 I( 10-' (I) 1 I( 10"1 Z x 10 ' 3 x 10.3
Z It 10-3 (SI.O) 4 It 10.'
Strontiua-90
ThoriUII.2]Z
AllIer i c i UIII- 241
Cobelt-60
C.sh.-137
Carbon-1'
Hydrog.,,- 3
(tri t h",)
1.
For .. poaealon . UN of .. 1OUf'C. of lonll'''' or electronfc prOlb:t r8dfatfon and for
regulatl". the cll.,...1 and ltandll". of r8dloactlve ..ut. In r..trlcted ara.- Aver...,
cancantraCI- of radlooctl.lty In air or !MIter above natural back,,...... Ex~lPtlona exist.
Used f. 1 IatC'", Ind..1..1 ~. In r..tricted ara., 88ftlta,., ....,. r.l....., and oth.,.,.
2.
3..
. USed f. ........ to .1ft0f'8 (1ftiIr 18), e.posure in """..trlcted a~, expoaur. at tho ~ry Of
a r..trfcted aree, Incfd8nt notification, and other..
10.
(S) -- $oh.ol..
5.
(I) -- Insol\.Dla.
6.
(SI.O) ..... w..nlon.
Source: ledloactlve ...tarlal' '916 (poa....lon, use and disposal of redfoacCflro .-at. and _tarfal). ~2 u'
100, lCant'-Cky Cabinet f. *-' 188OUI'C".
-------
03/26/1991
PAGE 1
CURRENT and PROPOSED HCLs, HCLGs, and SMCLs
CHEMICAL
HCL
(ppm)
, HCLG
(pplD)
---------------~~----------------------------~-----------------------------
, I NORGAlt'ICS
SMCL
(pp.)
Aluainua (1/91.
Antil80ny (7/90.
Ar.enie (NPDIIR.
~.be.tQ. (1/91.
Bariu. (NPOMR.
Bariu. (1/91 ...
Berylliu. (1/90)
Cadaiu. (1/91.
Chlori~e (NSDWR)
Chro.iu8' (1/91.
Color (NSDWR)
Copper (8/88)
Corro.ivity (NSDWR)
Cyanide (1/90)
Pluoride (4/86)
poaaing Agent. (NSOMR)
Iron (NSDWR)
Lead (NPDWR)
(8/88)
(6/90)
, .
I .
.
Proposed MCL and HCLG
. 0.01/0.005
0.050
1 .illion
1.00
, . 2
. 0.001
0.005
0.1
. 1.3
. 0.2
4.0
0.05-0.2
. 0.003
fiber./liter (>10 u.)
. 2
. 0
0.005
0.1
* 1.3
. 0.2 '
0.050
. 0.005 . 0
0.015 (Action Level)
250
15 color units
1
Noncorrosive
2.0
'0.5
0.3
-------
03/26/1991
PAGE 2
CHEMICAL
MCL MCLG SMCL
(ppm) (ppm) (ppm)
--------~----------~---------------------------------------~---------------
Manganese (BSDIR.
Mercury (1/91. '
Nickel (7/90.
Nitrite (a. B) (1/91)
Nitrate (a. B. (1/91)
Total (a. N) (1/91)
Odor (NSDD)
pH (NSDWR)
Seleniu8 (1/91)
Silver (1/91) ,
Sulfate (NSDWR)
Sulfate, '(1/90)
Thalliu8 '(7/90)
Total Dissolved Solids
line (BSDWR)
0.05
. 0.002
. * 0.1
1
10
10
0.002
* 0.1
1
10
10
0.05
0.05
3 threshold odor'
6.5 - 8.5
0.1
250
*400/500 .400/500,
* 0.002/0.001 * 0.0005
(NSDWR)
500
5
*
-. Proposed MCL and MCLG
-------
r
I
I
03/26/1991
CHEMICAL
PAGE 3
~L ~W S~L
-----------------~------------------- (ppm) (ppmt (ppm)
. -------------------------------------
ORGANICS
Acrylaaide
Adipate8
(Di(ethylhexyl)adipate) (1/90)
Alachlor (1/91).
Aldicarb (1/91 **)
Aldicarb sulfone (1/91 **)
Aldicarb sulfoxide (1/91 **)
Atrazine (1/91)
Benzene (1181 t
Carbofuran (1/91)
Carbon Tetrachloride (1181)
Chlordane (1/91)
2,4.-D . (1/91) .
Dalapon (1/90)
Dibroaochloropropane (DBCP) (1/91)
o-Dichlorobenzene (1/91,5/8'):
p-D,J.chlorobenzene (1l87)
p-Dlchlorobenzene (1/91,5/89)
1,2-Dichloroethane' (7/81)
ci8-1,2-Dichloroethylene (1/91)
tran8-l,2-Dichloroethylene (1/91)
1,I-Dichloroethylene. (1/81)'
Dichloroaethane
(Methylene chloride) ,(1190)
1,2-Dichloro~ropane (,1/9It
Diguat (1/90)
oinoseb (1/90)
Endothall (1/90)
,Endr i n (N'PDWR)
Endlin (7/90)
(1/91)
*
Proposed HCL and HCLG
TT
* 0.5
0.002
* 0.003
* 0.003
* 0.003
0.003
0.005
0.04
0.005
0.002
0.07 .
* 0.2
0.0002
0.6
0.015
0.005
0.01
0.1
0.001
* 0.005
0.005
* 0.02
* 0.001
* 0.1
0.0002
* 0.002
o
* 0.5
o
* 0.001
* 0.002
* 0.001
0.003
o
0.04
o
o
0.01
* 0.2
o
0.6
0.015
0.01
0.005
o
0.07
0.1
0.001
. * 0
o
*.0.02
* 0.001
* 0.1
* 0.002
-------
03/26/1991
CHEMICAL
PAGE 4
MCL MCLG SMCL
.. ( ppm). ( pPIl). ( ppm)
-~-~----------.--------~------------------------------------------
ORGANICS
. Epichlorohydrin (1/91)
Ethylbenzene (1/91,5/89)
Ethylene dibroaide (BOB) (1/91)
Glyphosate (7/90)
Heptac~lor (1/91)
Heptachlor epoxide (1/91) .
Hexachlorobenzene (7/90)
Hexachlorocyclopentadiene(HEX]
Lindane (1/91)
Methoxychlor (1/91)
Monocblotobenzene (1/91)
Oxaayl (Vydate) (7/90)
PAHsl. (7/90) .
Benzo(a)pyrene
Benzo(a) anthracene
Benzo(b)fluoranthene
Benzo(k)fluoranthene.
Chrysene .
Dibenzo(a,h)anth~acene
Indenopyrene
(7/90 )
*
.Proposed MCL and MCLG
-
'l'T
0.1
0.00005 .
. 0.1
0.0004
0.0002
* 0.001
* 0.05
0.0002
0.04
.0.1
. 0.2
. 0.0002
. 0.0001
. 0.0002
* 0.0002
* 0.0002
. 0.0003
* 0.0004
o
0.1
o
* 0.1
o
o
* 0
* 0.05
0.0002
0.04
. 0.1
. 0.2
0.03
0.008
. .0
. 0
.. 0
. 0
. 0
. 0
. 0
-------
03/26/1991
CHEMICAL
PAGE 5
~L ~W S~L
(ppm) (ppm) (ppm)
------------------------------------------------------------------
Pentachlorophenol (1/91 **,5/89)
Phthalate.
(Di(ethylhexyl)phthalate) (7/90)
picloram (7/90)
Polychlorinated biphenyl.(PCBs) (1/91)
Simazine (7/90) .
Styrene il/91,5/89)
2,3,7,8-TCDD (Dioxin) (7/90)
Tetrachloroethylene (1/91)
Toluene (1/91,5/89)
Toxaphene (1/91)
2,4,5-TP Silvex (1/91)
1,1,2-Trichlorethane
1,2,4-Tr!chlorobenzene
1, 1, I-Trichloroethane
Trichloroethylene
Trihalomethanes (NPDwa)
Vinyl Chloride (7/87)
Xylene. (1/91,5/89)
(7/90 )
(7/90 )
(7/87)
(7/87 )
*
Proposed. MCL and MCLG
* 0.001
* 0.004
* 0.5
0.0005
* 0.001
0.1
* 5xl0E-8
0.005
1
0.003
0.05
* 0.005
* 0.009
0.20
0.005
0.100
0.002
10.00
* 0
* 0
* 0.5
o
* 0.001
0.1
* 0
o
1
o
0.05
* ~.003
* 0.009
0.20
o
o
. 10.00
0.03
0.01
0..04
0.02
-------
03/26/1991
CHEMICAL
MCL
(ppm)
PAGE 6
MCLG
( ppm) .
SMCL
(ppm)
---------------------------------------------------~--------------
MICROBIALS
Coliform bacteri, (6/89)
Giardia .laablia (6/89) .
Heterotrophic bact. (6/89)
. Legionella. (6/89) .
Viruses (6/89)
Turbidity
RADIONUCLIDES
Beta particle and
photon radioactivity
Gross Alpha particles
Radium-226 and
Radiua-228 (Total)
< 1/100 inl
'1'T
'1'T
ft
'1'T
1 TU (up to 5 TU)
4 arem
.15 pCi/l
5 pCi/l
*
Proposed MCL and MCLG
o
o
o
o
o
(units of turbidity)
o
o
o.
-------
11/85
4/86
'7/87
8/88
5/89
6/89
6/90
7/90
1/91
1/91 **
HCL
HCLG
NPDWR
NSDWR
PAH.
SHCL
'1"1'
.
03/26/1991
PAGE 7
FOOTNOTES
50 Pederal Register (FR), November 13, 1985
51 FR, April 2, 1987 - Final HCLs and SHCLs
52 PR, July 8, 1987 - Final HCLs and'HCLGs
53 PR, August 18, 1988 - Proposed MCLs and HCLGs
54 PR, May 22, 1989 - Proposed SHCLs .
54 FR, June 29, 1989 - Final HCLs and HCLGs
Action level. for lead in drinking 'water, June 21, 1990,
He80randU8 fro. the Office of Emergency and Remedial Response
and the Office of Waste Program Enforcement .
55 FR, July 25, 1990 - Proposed' HCLs, HCLGs, and SHCLs
56 FR, January 30, .1991 - Final HCLs, HCLGs, and Proposed SHCLs .
56 FR, January 30, 1991 - Re-proposed MCLs and HCLGs
Haximum Conta.inant Level
Haxi.u. Cont..inant Level Goal
National pri..ry Qrinking Water Regulation
National Secondary Drinking Water Regulation
Polynuclear Aroaatic Hydrocarbons
Secondary Maxi.u. Cont..inant Level
Treat88nt Technique
*
Proposed HCL and HCLG
-------
APPENDIX D
SUPERFUND FACT SHEET PROPOSED PLAN -
MAXEY FLATS DISPOSAL SITE
-------
Superfund Fact Sheet
Proposed Plan
-------
and
V.S. EPA Records Center
Region IV
3~5 Courtland Street, N.E.
Atlanta, Georgia 30365
(~o.a) 3~7-0S06
Hours: Mon. - Fri. 8:00 a.m. to S: 00 p.m.
EPA may modify the preferred remedy or select another re-
sponse action presented in this Proposed Plan and the FS
Repon based on new infonnation or public commentS. There-
fore, the public is encouraged to review and comment on i11
the alternatives idenrifiedhere. A Glossary of Tenns can be
found at the end of this Proposed Plan to define the high-
lighted tenns used throughout this documeriL
Dates.to remember:
MARK YOVR CALENDAR
Public IIMtIng
for i.
....., AN
SUlMffund Site
une 13,1991 .
7:00 p.rn.
. June 13, 1991.
Public Meeting at the Ersil P. Ward (fonnerly Fox Valley)
Elementary School,
State Road 32, Fleming County, Kentucky
at 7:00 p.rn. .'
SITE HISTORY
The Maxey flatS Disposal Sire (MFDS) is located approximately 10 miles nonhwest of the City of
Morehead, Kenrucky and approximately 17 miles south of Flemingsburl. The MFDS itself occu pies
280 acres in eastern Fleminl County and is located on a ridge approximately 350 feet above the
valley floor. (See site area maps One and Two on the following tWo pages.) The site was purchased
by a private company, Nuclear Engineering Company (NECO, currently known as V.S. Ecology),
and the ownership of the land was ttan$ferred to the Commonwealth in 1963. The Commonwealth
issued a license, effective Jinuary 1963, to NECO to dispose of low-level radioactive wastes, and
leased the propeny to NECO. From May 1963 to December 1977, NECO managed and operated the
disposal of low-level radioaaive waste at the MFDS. It is esritt'tllted that 4,750,000 cubic feet of
waste materials were disposed of-at the MFDS. .
"Low-level radioactive waste (lLRW) is material that has come in conract with radioactive matenal
or that i~ itSelf, a source of low levels of radiation. Among other sources, LLRW comes from
nuclear power plants in the fonn of ruter materials or protective clothing. from hospitals and univer-
sities as laboruxy and diagnostic: waste, and from diverse indusaies such as drug manufactUrer5 and
producers ofwell-drilling equipment that utilize radioactive sources. By definition, LLRW does not
include spent nuclear fuel 01' weapons-grade nuclear material.
In order to protect public health and the environment from exposure. U.RW must be isolated \01( h Lle
itS radioactivity is decaying. To achieve this isolation at the MFDS, LLRW was deposited at the site
using the shallow land burial disposal technology. The waste wu disposed of in 46 large Q'enches
(some up to 680 feet long, 70 feet wide and 30 feet deep) which cover approximately 27 acres of
land within a 4~-acre fenced portion of the site GOwn u the Restric:ted Area. However. ..hot
wells" were also used at the MFDS for the burial of small-volume wasteS with high specific ace.. \ ry.
Most of the "hoc wells" are 10 to IS feet deep. constrUCted of concrete. coated steel pipe or cle. .l..,d
capped with a large slab of concrete~
2
-------
w
II
.
NOTE: ADMrED '''OIl KENTUCKY
O"'C'AL HIGHWA r M~
KENTUCKY
lOCA'tON 0' "'01
"''''''Il''''UCU .OT TO KAU
L . . "
,t . .
leAU .. M'U'
"
.
MAP PRODUCED BY EBASCO SERVICES INCORPORATED AND lABEllED FOR
THIS REPORT BY 8001, AlLEN. HAMIL TON. Inc.
MAXEY FLATS DISPOSAl.. SITE
LOCATION MAP
YAP 1
--
-------
HAP PRODUCED 3Y ElASCO SERVICES INCORPORATED AND -*3-
THIS REPORT BY BOOZ. ALLEN & HAMILTON, nc
MAXEY FLATS DISPOSAL SITE
VICINITY HAP
HAP 2
-------
The ~~ch wast~S were deposited in both solid and solidified-liquid form. Some wastes"arrived at .
the Site 111' conwners such as drums, wooden crates, and concrete or cardboard boxes. Other wastes
were disposed of loosely. Fill material (soiD, typically 3 to 10 feet in thickness. was then placed
over the O"Cnches to serve as a protective cover. After 1977, six additional O"Cnches were excavated
for the disposal of material generated on-site. (See trench location map on following page.)
Unexpected problems arose at the site in the ear~y 197Qs. It then became apparent that water enter.
ing the trenches had become the pathway by which radioactive contaminantS - primarily Tritium, a
radioactive form of hydrogen - were beginning to slowll migrate out of the disposal trenches. The
Commonwealth of Kentucky conducted a special study 0 the site in -"1974 to determine whether the
MFDS posed a contamination problem. The study confirmed that Tritium and other radioactive
" " contaminantS were migrating out of the O"Cnches and that some radionuclides had migrated off.site.
""
In 1977. while constrUcting a new trench. it was discovered that leachate was migrating through the
subsurface geology (approximately 25 feet below ground surface). Subsequently, the Common-
wealth ordered NECO to stop receiving and burying radioactive waste. In 1918. the Commonwealth
and NECO entered into an agreement under which NECQ's lease was terminated. The Common-
wealth then hired private companies such as Westinghouse Electric Corporation (the current site
custodian) to stabilize and maintain the site. """
Those steps, however, were temporary and a final closure plan was needed to ~ the problem at
the MFDS. EPA, therefore, proposed the MFDS for inclusion on the National Priorities List (NPL)
of hazardous waste sites to be addressed under the Superfund Program in 1984 and. in 1986, this
action was fmalized. A group of organizations who participated in waste disposal at the site (named
as PotentiaJIy Responsible Panies [PRPs]) joined together as the Maxey Rats Steering Committee
(Committee). The Committee conducted and pani&nY funded the technical work required for the
Remedial Investigation/Feasibility StUdy performed at the site. The largest ponion of costS incurred
in conducting the RI/fS were paid by the Department of Defense (DOC) and the Depanment of
Energy (DOE), both named as PRPs but not members of the Commiaec. These actions have now"
culminated in a preferred remedy being prepared by the EPA.
On January 13, 1989, EPA, throulh the Technical Assistance Grant (TAG) program. provided
550,000 (the maximum available under the Superfund Program) to the Maxey Flus Concerned
Citizens (MFCC). This money wu granted to MFCC for the purpose of hiring technical a.dvtso~ to
help the local community understand and interpret site-related technical information and advise the
community on itS panicipation in the"decision-maJcinl process.
REMEDIAL INVESTICA TlON CO~CLUSIONS
The Remedial Investiption (M. which was initiated at the Maxey FIus Dis-
posal Site (MFDS) in 1981. included the collection of more than 700 samples
at. and adjacent to. the Maxey flatS site. from environmental mecUa such u
trench leactwe. soiL pound Wiler, surface water," sueam secI1meat. and pound
water. These Sllllples were analyzed for a varieey of radiolOliCal"and non- "
radiological (~1s. metals. etC.) constitUentS.
fliŁJ
The RI idenDfied a1al1e nnp of contaminant concenD'alions in samples col-
lected from Il'eDChes in different pans of the Resaieted Area. In addition. site records indicate ,that
sample analyses (Tritium. poss alpha and beta panicle analyses) &om the same trench sump yteld
varying concenaations at different rimes. Approxima1ely 2.8 million pllons of leachate were
calculated to be in the trenChes. The O"Cnch leachate conllins I variety of radionuclides (of which
Tritium is the most predominant). In general. the' non-radiolopcal chemical concentrations in a-ench
leachate samples were low (less than 10 p~ per million for organics) and 8;l1 samples ~yzcd In
compliance with the Resource Conservation and Reco~ery Act (RCRA) )'1clded negaave resultS.
5
-------
TRENCH SUMP
APPROXIMATE
BOUNDARY
OF IRENCH
FfNCELINE AND
BOUNDARY OF
RESTRICTED
AREA
APPROXIMATE
AREAS COVERED
BY PVC
MAXEYFLAT DISPOSAL SITE
TRENCH SUMPS. AND BUILDINGS IN RESTRICTED AREA MAP
-------
The RI demonstrated that on the west. side of the site. trench leachate migrates horizontally ~ugh
fractures in a thin siltstone :geologic layer called the Lower ~arlcer Bed. which lies approximately 15
feet below ground surface In that area. On ,the east side. the. horizontal migration occurs in the
fractured siltStOne layers of another geologIc layer. the Farmers Member. which begins approxi-
mately 40 feet below ground level. (See Geologic Cross Section of site on following page.) Vertical
migr.uion betWeen geological layers is limited by shale layers of low penneabilicy. which act as
aquitards. Because the MFDS is bounded on three sides by steep slopes. the contaminated leachate
migrating through the fractured si1ts~one layers moves into the bonom of the soil layer on these
slopes. However. not all leachate rrugrates to the bottom of the soil layer on the slopes. as evidenced
by cite occurence of seeps on the east hillside.' .
. The RI detennined that ground water samples raken from monitOring wells in rite Lower Marker Bed
had higher Tritium concentrations (up to 2.000.000 pCilmI) than samples taken from deeper geo-
logic unitS. These Tritium concentrations and the presence 'of other radionuclides indicate that the
contamination was caused by trench leachate. On the east side of the site. the Forty.series
trenches. which commonly bottom near the tOp of the Fanners Member. provide Tritium and other
conumination to the Fanners Member. .
, .
In the. soils on the three slopes adjacent to the site. Tritium is the predominant contaminant. with the.
largest contaminated areas and highest levels of Tritium contamination on the upper pan of the
.northwest side of the site. Other contaminantS detected in soils which could be amibuted to the
MFDS include Cobalt-60. Toluene. and Arsenic. Previous testing alonl the soil-rock interface by
the Commonwealth also indicated the presence of radionuclides such as SlrOntium-90. Carbon-14,
and.Plutonium-238 and -239.. . .
Surface water and sediment investigations during the RI involved the collection and analyses of
samples from three principallocanons: Restricted Area surface water runoff (which exitS the site .
through three water control suucnues located at the periphery of the Reslricted Area). from off-site
creeks. which receive runoff from the MFDS. and from off-site sources.
Tritium and Radium-226 were the only radionuclides detected in the SurflCe wuer samples during
the RI. Concentrations of Tritium were highest at the water control suuc:tUreS adjacent to the Re.
stricted AreL The principal sources of Tritium enterinl these sauctureS are contaminated liquids.
which have migrated from the lrenches to the sJopes through fnaured bedrock. and aonospheric
releases of tritium from the trenches. Tritium levels in the. surface wirer ~Ied from less than 10
pCi/mJ to 60 pCi/m1. Tritium ranged in concentration from less than 10 pCi/ml1O 70 pCi/mJ in
sediment moisture. Analytical resultS show low concenrrations (rusinl from , ppb to 98 ppb) of
. chemical constituents in surface water. Sediment sample analyses indicated chemical constituents
ranging from , pans of the chemical per billion pans of the unit sampled (pans per billion or ppb) to
1800 ppb. The probable source of the higher con'centrations (phthalate esterS) is the PVC used CD
cover the trenches because the concentrations were hiihest II the sample swions adjacent t.o the
Restricted Area. and the phthalate ester was only detected in samples associated with surface water
runoff from the RestriCted Area. .
The Commonweal~ of KentUCky has deteeted S rrontium~90 in surface warcr in the East Main
Drainap Owmet. 1be Commonwealth has also deteCted SlrOnaum-90 in the east pond. at the east
pond oudet. aDd ill the soum drainale area. AdditionaJIy, the Commonwealth has detected Tncum
concenD'UiODl in various site drains in excess of 1000 pCiIml.
In summary. the decay of-containers (cardboard. wooden. ~ etC.) over time has allowed the
trench caver to settle becluse the containers no lonler provide sufficient s1rUCtUrl1 suppon for the
trench cover. A pcindinl effect has mulled from the collection of rainfall and sno~lt in' the
subsided trench cover. The infilcration of precipitation rhroup die cnciced and subsided cover
generateS trench leachate which creates an additional hyclrauUc bell'" forcinl more leachate out of
the slopes intO the environmenL This decay. collapse. and pondinl effect, as stUdied and docu-
7
-------
N W
1 100
1 13SO
Z
o
- 1000 ;
»50
- »00
EXPLANATIQM
MMnOK CMMMMf
CONTOUR INTERVALS;
50 pCf/ffll
100 pC1/ml
lOOOpCI/ml
10,OOOpCI/ml
100,000 pCJ/ml
1,000.000 PCI/ml
• MONITORING WILLS SAMPLED AND
ANALYZED FOR TRITIUM IN PORE WATER
HAP PRODUCED 8Y EBASCO SERVICES INCORPORATED AND LABE.
REPORT BY BOOZ. ALLEN & HAMILTON, inc
'MAXEY aATS DISPOSAL SITE
GEOLOGIC CROSS SECTION MAP
MAP 4
-------
. ment~ during the Maxey flatS RI and numerous. studies conducted previously. have resulted in the
migrauon of radicnuclides from. the trench disposal are3. .
SUMMARY OF SITE RISKS
~s pan of the ~S. an assessment of si~e ri~ks was perfonned using existi~g site data and infonna-
non gathered dunng the Remedial Invesnganon. to evaluate the natUre and extent of contamination
ar the Maxey Aats Disposal Si,e (MFDS) and [0 identify !he contaminantS. transpon mechani:ims.
and exposur~ pathways which pose the greatest potential threat to human health and the environ-
menL. The Risk Assessment evaluated the risk associated with a No Action alternative. which
~ssumed that [he site would be abandoned and that no activity would take place. other than monitOr-
mg.
Potential routes of exposure to contaminantS. or exposure pathways. were developed based on both
the current site conditions and the traditional pathways examined for a public health evaluation. The
potential contamination sources include trench,material. leachate. site strUctures. above-ground
tanks. ground surfaces. ground water. and soil. Potential exposure routeS include the ingestion of
crops and anima! products. including fish. game and livestock: the inhalation of air; and direct
contact (e.g.. dermal contact. ingestion. intrusion) with contaminated media..
Two setS of potential exposure pathways were evaluated for the MFDS. The first. referred to as non-
intrUder pathways. assumed that the site .would be abandoned. but then an individual would move
onto and construct and occupy a c;iweUing in an area of the abandoned site. currently known as the
Restricted Area. .
Non-intruder pathways include the following~
.
Surface Water Pathway - In this pathwa.y, contaminantS move off-site in ground
water and enter the surface water system. The stream water is then used as a drink-
ing water and irrigation source for beef and milk cows and their forage. Humans then
ingest the anima! productS.
Evapotnnspintion Pathway -. This pathway involves the uptake of contaminated
liquid into plana and evapotranspiration of the contaminantS to the environmenL
(Note: Evapotranspiration is the release of water vapor &om plantS to the atmos-
phere.) Tritium is the only contaminant to move by this pathway. Once released [0
the air. the ttitium could be incorporated intO food and drinking water sources or
direaly inhaled by a human. .
.
.
Deer Pathway - 1n this pathway, contaminated water moves thmup the ground
warer syStem to the hillsides adjacent to the sile.Upoa relChinl the hillside. the con-
taminaJion is incorporated into plants; The contamiJwed plana ire then eaten by
deer fanJin. on the slopes. Also the deer drinks contaminated warer from the
mams. 1be contaminantS arc then incorporued into the meat of the deer. A hunter
kills die deer and inleStS the meaL
Sediment Puhway - This pathway involves the movement of contaminantS in ground
wala'to the billpdes adjacent to the site and into the surface warer system (streamS).
As the contaminared surface water moves throup the scream bed, some of the con-
taminantS adhere to the soils in the SU'WD bed. Then throup the course of p~y In
the saeam beds. a child ingestS the conWDinaceci soils. .
.
.
Well Water Puhway - This pathway involves the movement of contaminants lit
ground water to the hillsides adjacent to the site and into the surface water system
moving down the hillsides. At the boaom of the hillsides, the contaminated runoff
9
-------
,-----
.
recharges the alluvium (soils). A well is excavated in the contaminated alluvium and
a family uses the well as a source of drinking Water for a family.
~oil Erosion Pathway -- Thi~ path~ay involves the resuspension in air of soil par-
tlc.les contaminated with radionuchdes an~ the washing of soil intO the surface water.
It IS assumed that the trenches overflow with contaminated liquids and radionucHdes
adhere to surface soils adjacent to the crenches. The leachate subsides in the trenches
and .the surface soils dry. This dry contaminated soil is then suspended in air and
camed to a person and inhaled or washed away in runoff. Also, crops are grown on
~ area of alluvium (base of hillsides) contaminated by surface runoff. A person
ingestS contaminated fann products and is exposed to external radiation.
Trench Sump Pathway -- This pathway. involves the escape of aitiated water from
trenches via trench sumps and cracks in the a:ench cap. . A person then inhales the
contaminated air.
.
The . second set of potential pathways, the intrUder pathways. alSo assumed thll the site .would be
abandoned. Non-intrUder pathways. however, primarily involve off-site paths of exposure, which
are not associated with occupation of the site. The intrUder pathways include the following:
. .
IntrUder-ConstrUction Scenario -- This pathway involves the assumption that no .
controls exist for the site and an intrUder inadvertendy occupies the disposal site and
begins constrUction activities. ConstrUction activities penenre and expose the waste.
Human exposure would occur through external exposure 10 the contaminated soil and
inhalation of contaminated air. . .
.
.
IntrUder-Discovery Scenario -- 'This pathway assumes that. durinl the above-de- .
scribed constrUction scenario, the intrUder contactS solid remains of waste or bamen,'
realizes thl1 sOmething is wrong. and ceaseS consuuetion activities.
IntrUder-Agricultural Scenario -- This pathway involves the usumption that no con-
trols exist for the site and an inadvertent intrUder occupies the site. After some
constrUction activities, the intrUder (site resident) bepns a8ricuhural activities. It is
assumed that some percent of the intrUder's annual diet comes from crops raised in
the contaminated soil and from food productS produced by animals. External exp
-------
(mrenyyr), almost half of which is attributable to Tritium. The upper bound estimate for such a
see.nano would total 4300 mrenv'year. For each ve~ of e'tpo$u~, under a No Action alternative, it is
esnmau:d that the average case (75 mrem) lifetime nsk of cancer would be 3 x lO's (or three in
100,(00) and for the upperbound case (4,300 mrem) it would be I x 10"' (one in 1.(00). EPA's
target risk ranp is. I. x I~, or one additional occurence of cancer in 10,000, to I x 10-6. which
equates to one addinonal OCcurence of cancer in.l ,000,000. The average case lifetime risk. of cancer
from manv ~ucceui~t! vt'!8n of expo~ure would be approximately I x 10"' or one in 1.000, and the'
upperbound cancer nsk would be 6 x 10"1 or six in 100. In both cases, the risk significantly exceeds
EPA's target risk range and the MFDS remediation goal of 25 mrem/year.
In addition, during the 7Q-year time frame. the time frame that is typically used to calculate risks at
Superfund sites. Tritium and Strontium-90 would exceed drinidng water limitS in water extracted
from wells al the base of the slopes. Funhermore. Tritium. Strontium-90. and Radium-226 would
exceed drinking wacer limirs II this 1ocalion durinl the 500 year time frame. AssessmentS using the
500.year time &ame were made for the MFDS because of the lonl-lived radionuelides present.
IntnJd~r Ri~k~
For the most siJDificant of the incruder pathways. the Intruder-Agricultural Pathway, whereby a .
person occupies a house on.site. the average case exposure totals 1 dose equivalent of 26,000 mrem/
year under a No Action alternative. Under the same scenario. the upperbound estimate would total
~~~~m~==:-~te~~f~::~~~tr;'PO~!O;:~rh
~ a person would live on-site. under the no action altenWive. the avenp case lifetime risk of
cancer would be approximalely 1 x 10'2 or one in 100. Under the same scenario. the upper bound
case risk of cancer would be 4 x 10" or four in 10: BoIb cases sipificandy exceec:t EP A's target risk
range. Pmlonlled e~Dmltm!!I (many successive yean) would result in a lifetime risk of cancer ap.
proaching one additional cue of cancer for each person who would reside on the siu:.
Assuming that occupanc:y of the site would DOC occur for 100 years. the doses and associated risks
under a No Action alrenwive would decrease. but only by a small marlin because most of the expo-
sure is associated with the reWively IOD..lived radioauclides. Tritium and Saontium-90 would no
longer conaibute to the dose because they would have decayed away. and the longer-lived radionu-
elides. such as Radium-226, Tharium-232. and Plutanium-238 would become the significant dose
eonaibuun. Bcyonc1100 years. the risks associated with the MFDS remain unacceptably high and
tend to become constant ruhcr dw1 decreuinl sipificandy. EvCD after 500 years. on-site occu-
pancy wouJd result in risks eueedinl me KCepcable risk ranp. For dUs reason. the need for im-
plemenwion and lundin. of institutional CODII'Ols, mainteriaDce. and monitOrial in perpe~ity is
ap~nL .
The threatened release of hazIrdoUs substances flam the MFDS. if DOC addressed by the preferT'ed
. remedy or one of the cxber ICM measures coa.sidercd. may present a potential threat to public
health. welfare. ar die CIIViR)nIftl!DL
SUMMARY O. APPLICABLE OR RELEVANT AND APPltOPIUA TE REQUIREMENTS
. (AKAKS)
Sectioa 121(d) atCERa.A reqaa dwu the completioo of remedial actiem. the remedy shoul~
achieve alewl at c:omraI wlUch complies with federal aDd SWI: enviroameotallaws thai are appli-
cable arrelevam aDd approprWe 8D the hazardous subsllDCCl, pollutaDa. or conwninanrs at the me.
Therefore. to be seleaed u the remedy, aD al~ve mUll mea all Applicable or Relevant and
Appmprim RequirememI (ARAKI) ar I waiver mus be obaiDed. AppeDdix A of the Maxey flatS
. site Feasibilicy Study Repan sbouJd be coasulled tor I comple. disc:usIiOD of A.RARs thal apply to
the Maxey f1aIs sie. 1be followiD. is a list of major requimDeDa dw mUSt be met by the sel~ted
remedy:
11
-------
. .
.
Occupa.tional Safety and Health (OSHA) Standards (19 Code of Federal Regulations
or CFR. Pans 1910.120. .1000. .1500. Pans 1926.53. p50. .653) "
National Emission Standards for Hazardous Air PollutantS (40 CFR 61.92)
.
Kentucky and Federal Radiation Protection Standards (902 KAR 100:020. :025.
Table I. Table II. and 10 CFR 20.105) :
Kentucky Licensing Requirements for Land Disposal of Radioactive Waste (902
KAR 100:022)
.
.
Kentucky Standards for the Disposal of Radioactive Material (902 KAR 100:021.
Sections 7 and 8) .
General Kentucky RequirementS Concerning Radiological Sources (ALARA) (902
KAR 100:015. Sections I and 2) "" "
.
.
Kentucky Fugitive Air Emissions Standards"(401 KAR 6:QI5)
Federal Dritoong Water Regulations (40 CFR Pan 1410 Subpan G). and
.Resource Conservation and Recovery Act (RCRA) (currently under consideration as
a potential ARAR) "
.
.
The pointS of compliance at the Maxey flatS Disposal Site for SOrr1e of the previously ARARs are as
follows:': :
.
National Emi"$ion" Standard~ for Hanrdou!I Air PoUutan(!l - the effective dose
equivalent of 10 mrem per year will be judged at the site propeny boundary
Kentuc~ and Federal Drinkin, Water Standard! . the point of compliance for these
standards begins at the contact of the alluvium with the hillside and ending at the
streams; compliance will be based on samples taken in the alluvium
.
Kentuc~ Licen~n, Requirement~ for Land Di~a1 of Radioactive Waste. the 25
mrem per year dose limit set forth in this requirement will be judged on the combined
doses contributed by the air, water, drinkina water and soil pathways. The point of
compliance for this requirement will be the maximum point of individual exposure
which is at or beyond the site boundary.
Under the Superfund program. the selected remedy muSt meet all applicable at relevant and appro-
: priate requirementS (ARARs), which include federal"and stare s~ or a waiver must be ob-
tained.. If a Stale has a more strinlent, promulgated standard than itS federal counterpan. the more
stringent Stale cn"Ctvd shall be used. The Commonwealth of Kentucky has identified a scate stan.
~ which it c:oasiders to be an ARAR: KRS 224.877(4). This is a rwruive. non-degradanon
requirement .wbich requires resroruion of the environment to the extent practicable.
.
EPA considers KRS 224.877 to be a general goal, which does noc set out a specific, enforceable
cleanup Standard that is more stringent than federal law, and which is noc a bindinl requiremenL For
this reason. EPA does noc consider it a cleanup ARAR. ""
R-lir fX &he poaible I"'~ of haardous WIlla U the MFDS, EPA cumndy is CCIIIiderinI whecher R CRA IS
aD ARAR and if so. EPA is coasiderinl die possibility of.. ARARs wUverwilb respec:& CD die Unci DisposaJ
ResIriaian panion of RCRA. The pIftiaI RCRA waiver for die site would be based upoa rechnic:aJ imprĄDc.abul[)'
and/or pearer risk 10 humin heallh and the envitonmenL Waivers of ARARs are aUowed undr:r CERC'LA See uon
1 21(cI).
12
-------
SUMMARY OF ALTERNATIVES
The primary objective of the FeasibilitY Study <.FS) is to. ensure that appropriate remedial alternatives
are developed an.d evaluated such that relevant 1nfonn~uon cOncerning the remedial action options
can form the basIs for remedy selection. The FS descnbes and evaluates options for mitigating
unacceptable leve~s of ~Ul1'ent or future potential risks associated with exposure to site contaminantS.
Information conwned I~ the RI Repon. Risk Asses~men~. and other site data are consideRd in the
FS to develop these opnons. Subsidence of waste diSpoSal trenches is the lowering of the trench
caps due to waste and cap consolidation over time. Areas affected by subsidence can range in size
from a few square feet .of a cap to the entire area occupied ~y a trench or group of trenches. Subsi-
dence can cause cap fallures by cracking or deforming the cap materials. Depressed areas com-
monly result in ponding of rain Water. which would have run off narurally if subsidence had not
occum:d. Both of these phenomena can lead to increased rates of water infiltration into the waste.
Therefore. subsided areas may require repair to prevent accumulation of leachate in the trenches.
Slow subsidence is evident in moSt waste disposal trenches at the MFDS. After a few yem. there-
fore. soil must be added to the trench surfaces and the caps must be reanded to maintain surface
water runoff. Subsidence resultS from a complex interaction of physical and chemical' processes in
the waste mass and. in time. subsidence works to consolidate the waste and trench. cap materials into
a smaller volume. resulting in a denser, more consolidated mass. .
The objectives of any remedial alternative considered for the MFDS are to:
. .
.
Stabilize the site such that an engineered cap could be placed over the trench disposal
area with minimallong-tenn care and rr1:Iintenance; . .
.
Protect human' health and the environment (meet all Applicable or Relevant and
Appropriate RequirementS); . .
Control infiltration intO the trenches and miaration from the trenches:
.
.
Address site concerns at the community, state and fedenllevels.
Eighteen potential remedial alternatives capable of achieving the remedial aaion objectives at the
MFDS were developed and evaluated. These 18 alternatives were then screened on the basis of their
effectiveness. implementability and COSL This screening produced a manageable group of seven
alternatives. Each of the seven alternatives' was then subjected to a detailed analysis which applied
the nine evaluation criteria established by the Superfund Amendments and Reauthorization Ad
. (SARA). .
The nine criteria used to evaluate altemarives ar.SupertUnd sires are u foUows:.
.
Shan-tam effecliveness - addresses the period of time needed to achieve protecnon
aad any adverse impactS on human health and the environment dw may be posed
durin. the conscruction and implemencation period. unci1 ~iaJ action objecnves
are IdIicved.
.
.
Lonl-cam effecliveness - refen to expected residual risk and me ability of a remedy
to maiDaiD reliable protection of human health and the environment over time.
Reduction of tOxicity, mobility or volume - is the anticipuecl perfarmanc:e of the
EreJI"!'eftt rechnololies' a remedy may employ. . .
Implemenubilicy - the technical and Idminisuuivc feasibility of a ~y. I nc I uGl n g
the availability of materials and seMcCs needed 10 impJcment a panic:u1ar opaon.
.
.
13
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.
Compliance with ARARs .. addresses whether a remedy wiIJ meet all of the ARARs
of Federal and State environmenrallaws and/or justifies a waiver~
Overall protection of human healt!t and the environment - addresses whether a
remedy provides adequate prOtectIon of human health and the environment and
describes how risks posed throug~ eac~ exposure pathway are eliminated. reduced. or
controlled through treatment. engmeenng controls. or institutional controls.
. .
CoSt -~ includes estimated capiral a.'1d operation and mainrenance (0 & M) COStS. also
expresSed as net present-worth COSts. . .
.
.
State acceptance.. indicat=s whether. based on itS review of the RI/FS Repons and
ProPOSed Plan. the State concurs with. opposes. or has no conunent on the preferred
alternative. .
Community acceptance -- Communiry acceptance summarizes the public's general
response to the alrematives. based on public comment received during the public
cOmment period. .
.
Although overall protection of human health and the environment is the primary objective of the .
remedial action. the remedial altemative(s) selected for the site must achieve the beSt balance among
the evaluation criteria. considering the scope and degree of the site conwriination. .
Cenain componenis (baseline features) are common to all remedial alternatives in the FS Repon for
the MFDS. with the exception of the No Acrion Alternative. Thesebaseline features are as follows:
.
.
.
.
Demolition of site structUres anddecommissioninl of sire facilities
Construction of additional disposal trenches
Procurement of a buffer zone adjacent to the existing sire property. and
Institutional contt'Ols.
The seven alternatives receiving detailed analysis in the FS Repon are described below and the
approximate COSt figures and design/construction times for each alternative are presented in
Table Ion page 18. following the deSCription of alternatives~ .
ALTERNATIVE 1- ~
The Superfund Program requires tIw the No Action alternative tM; considered at every site. It serves
as a baseline by which other alternatives are compared and it must be carried throup the derailed
analysis of alremuives. No Action for the Maxey Aars Disposal Sire consisu solely of monitoring
and activities in suppan of monilDrinl (e. I., installuion of monitOrinl wens).
The seeminaJy hip COlI of 6.8 miIJion dol1ars for an ahenwive involvinl only monitOring arises
. from the need 10 IDDIIiICl' this sire in pelperuity. This monitOrinl wouJd involve the installation of
additional monilarin. weUs and sample collection and analyses on I frequent basis. Sample analy-
ses would be ~ usinla hip level of quality assurance/quality conaol, thereby increasing
the cost of the analyses and the remedy.. .
The No Action alremative is lICK an engineered aliemuive, and it would noc satisfy the remedial
objectives. The No Action Alternative does not comply with ARARs and would. likewise, nOl
. provide overalJ protecUon of human health and the environment.
14
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Estimated Construction Cost: S 636.000
Es~mated 0 & M Cost: S 6.167.000
Esumated Present-Wonh Total CoSt: S 6.803.000
Estimated Implementation Time: 6 months
ALTERNATIVE 4 - STRUCTL'RAL CAP/DY!\IAMIC COMPACTIONL HORIZONTAL
FLOW BARRIER
Alternative 4 includes the following remedial action:
.
Ba5eline features
Leachate removal from the trenc hes
Solidification of leachate and disposal in new trenches
Installation of horizontal flow barrier (if needed)
Dynamic compaction of existi"g disposal trenches concurreniwith addition of com-
pacted soil and sand backfill
Installation of a tWo-foot thick reinforced concrete cap over the trenches and a tWo-
foot thick low-penneability clay cap over the rest of the closure area. Cap installation
would include drainage, vegetative cover, and erosion conaol. and
Remedy Review perfonned every five years.
.
.
.
.
.
.
This alternative combines the technologies of liquid waste removal. dynamic compaction and struc- .
tural capping. After leachate removal and dynamic compaction, a reinforced concrete structural slab
and several feet of soil cover would be placed over the disposal trenches. The use of dynamic
compaction on the trench area prior to placement of the slrUCtUral cap would provide a stable foun-
dation for the cap and minimize future subsidence. Without the suppon provided by stabilization, .the
reinforced concrete cap would not be capable of spanning the wide trenches.
The horizontal flow barrier should help reduce the off.site milJ'Uion of contaminantS and prevent the
inf1ltration of subsurface water.
Estimated ConslrUction Cost: S 59,332,000
Estimated 0 & M Cost: S 6,175,000
Estimated Present-Wonh Total Cost: S 65.s07,000
Estimat~ Implementation Time: 38 months
ALTERNATIVE 5 - NAnJRAL STAB" T7A.TION
The NatUral Stabilization altenWive combines elementS of conwinmenc. leachate removal. and
treatment. The distinJUishin. feamre of this 'altenWive is the use of III initial closure cap during a
period of natUral subsidence and maintenance, estimated to be I period ranain. from 35 to 100 years
(the interim maintClWlCe period). A fmal, muhi-Iayer cap willi synthetic liner would be installed at
the completioa of rwunJ subsidence, at which time the trenChes ,would form I stable foundation for
the final cap. ID addition, I horizontal flow barrier would be conmucted. if required. to prevent
ground wuer iDfUnIion intO the disposal trenches. With this alternative, a horizontal flow barrier
could include I ncnh cutOff wall or I cutOff wall which enc:irclesthe trenCheL
The implemenwion of this altemaave would involve the follow. activities:
.
Baseline Fea1ures '
Excavation of Additional Disposal Trenches for Disposal of Solidified Leachate and
Site Debris . , ,
Leactwe Removal from Disposal Trenches
Leactwe Solidification and Disposal in New Trenches
Periodic Installation of Interim Trench Cover
.
.
.
.
15
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.
lnstallanon of Horizontal Flow Barrie.r (if needed) .
Natural Scabilization With Active \-1aInt~nance and MonitOring
Installation of a Final Engineered C~p WIth Synmetic Liner. and
Remedy Review Performed Every Five Years.
.
.
.
Alternative 5 provides for the installation of an interim cap OVer the trench disposal area. Once the
trenches achieve the degree of stabilization required. a fi~al cap would be installed. Maintenance
requirementS for this alternative would be significant dunng the interim maintenance period. Once
the trenches have sUfficiently stabilized. the final.cal? would .be installed and maintenance.require-
ments would be minimal. Specific subsidence cntena would be developed in the remedial design.
Estimated ConstrUction Cost: $ 23.9W.OOO
Estimated 0 & M Cost: $ 9.643.000
Estimated Present-Wonh Total Cost: $ 33.553.000
Estimated Implementation Time: 35 - 100 years with 22 months for initial capping. 10
months for final capping
Alternative 8 includes the following remedial action activities:
.
Baseline features.
Leachate removal
Solidification of leachate into concrete blocks and disposal in new trenches.
Installation of Horizontal Flow Barrier (if needed)
Installation of an engineered soil. cap with synthetic liner, and
Remedy Review Every Five Years. .
.
.
.
. .
.
Trench stabilization would be accomplished by natural subsidence, assumed to be completed in 3S to
100 years. Subsidence monitOring and water infilcration monitOring would be perf'onned periodi-
cally and at other times when conditions are such that the potentia! for subsidence was high.
The required maintenance acavities for this alternative would be significant because trench subsi-
dence and resulting cap repair would be significant. The Horizonw Flow Barrier (assumed to be a
Nonh Cutoff Wall for this alternative) would prevent groundwater infiltration intO the trench area.
Estimated Consauction Cost: $ 34.302.000
Estimated 0 & M Cose $ 13.105.000
Estimated Present Worth Total Cost: $ 47.407.000
EsamaEed Implemenwion TilJ)e: 23 months.
.ALTERNATIVE 10-
MPA
DYNAMIC
Altemaave 10 iDcludes the foUowing remedial action activiaes:
.
"-seline fwures
LeacJwe removal
. SoJidificalion of leachate and disposal intO new D'enChes
InSUUaaon of. Horizontal Flow Barrier (if needed)
Dynamic compaction of existing trenches with c:oncurrent addiDon of compacted sou
and sand bacJdiU . .
InstalJaDon of an engineered soil cap with synthetic liner, and
Remedy Review Every Five Years. .
.
.
.
.
.
.
16
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D~namic compa~tion ~vo~ves the application ?f high-energy impactS to the ground sun:ac~: itS
pnmary p~se 15 to mcrease the ability of sOil and waste to suppan a cap. The dynanuc Impact of
a heavy weIght transmitS shock waves downward through the soil and wastes. rearranging the mate-
rial into a den,ser configuration. '
Prior to s~ng dynamic compaction. tW9 feet of silty sand would be placed over the entire area to
be dyn:muca!ly comt'acted. The silty sand would supplement the existing soil co\ler over the
trenches and prevent it being breached by the weight.
The cap would limit vertical infiltration: the existing contaminated leachate would'be removed and
immobilized: the cap stability would be established using dynamic compaction to minimize future
. subsidence: and ground water infiltration would be minimized due to installation of a horizontal
flow barrier (it is assumed that a Nonh Cutoff Wall would be installed with this alternative). as
needed. '
Estimated Construction Cost: $ 39.538.000
Estimated 0- & M CoSt: $ 4.790.000
Estimated Present-Worth Total Cost: $ 44.328.000
Estimated Implementation Time: 35 months
ALTERNATIVE 11-
Alternative 11 includes the folloWing remedial activities~
.
Baseline features
Leachate removal from existing trenches
Installation of a Horizontal Flow Barrier (if needed)
Grouting of accessible voids in the existinl disposal trenChes with JI'Out made from
potable water and/or leachate
Installation of an engineered soil cap with synthetic liner. and
Remedy ~eview Perfonned, Every Five Years. .
.
.
.
.
.
, Altemative 11 would achieve con&ainment with an engineered soil cap with synthetic liner and
Horizontal Flow Barrier (it is assumed that a North CutOff Wall with p-ave1 drain would be installed
with this altemaave). u needed. and tre&Dnent throulh leachate removal and poulin.. The distin-
guishina prorectiveneu feature of Alternative 11 is aench poutina. .
Groutinl would consist of injecUnl . mixture of marerials (e. I.. cemenl, bentOnirc. fly ash) and
water throup SDeCia1ly inscned probes into the majoricy of uencbes ID fill voids and other openings
. in the wasce. T&e p;m.ry purpose for groutina at Maxey Flus is to provide. Stable foundation for
, the final closure cap. .
EsUmared ConSUUClion Cose: S 61.870.000
Estimated 0 ct M Cou: S 6.989.000
Estimated Present-Wonb Total Cost: S 68.859.000 .
ESbJl\lted Implemenwion Time: 46 months
, , .
17
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ALTERNATIVE 17 - ENGINEERED SOIL CAP/DYNAMIC COMPACTION I
HOR! NT A W BARRIER .
Alternative 17 includes the following remedial activities:
.
Ba~lin: feature:;
Leachate removal .
Solidification of leachate and disposal into new trenches
Installation of a horizontal flow barrier (if needed) .
Dynamic compaction of existing disposa.l trenches concurrent with the addition of
compacted soil and sand backfill
Installation of an engineered soil cap, and. .
Remedy Review Perfonned Every Five Years.
.
.
.
.
.
.
Alt~ative 17 combines the remedial technologies of capping, dynamic compaction, and installation
of a horizontal flow barrier to stabilize the site. The difference betWeen this alternative and Alterna-
tive 10 is the type of horizontal flow barrier and cap. This alternative would involve installation 'of a
grout curtain to encircle the disposal trenches rather than the North Cutoff Wall; .
the engineered soil cap would not contain the synthetic liner. .
Estimated ConstrUction Cost: $ 51.920,000
Estimated 0 & M Cost: S 4.634,000
Estimated Present-Worth Total Cost: S 56,554,000
Estimated Implementation Time: 38 months
TABLE 1
Maxey Flats Disposal Site Present Worth Cost and Remedial DesipfRemedial
Action Implementation Times for Altematives
Alten\~tive
Design and
ConstrUction Time
(months)
Total Present
Wonh COSt
(millions)
1
4
5
8
10
11
17
06
38
22'
23
35
46
38
6.8
65.5
33.5
47.4
44.3
68.9'
56.5
, - Initial closure would be completed in 22 months.
followed by a 35 - 100 year Interim Maintenance
. Period, followed by a 10 month Final Closure Period.
18
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I'RITERRED REMEDY - :\:ATLRAL STAU((.(ZA110N
It is not kno~ ho~ long it will take for waste trenches to stabilize because of the many physical and
chemical variables Involved and the limited a:endt-spec:ific information upon which estimates are'
based. The namral Stabilization process at Maxey FlatS would allow the materials ~ subside natU-
r~ly to ~ ~tab.le conditi9n prior to final closure with an engineered cap. It has been estimated that
thIs stablhzanon process could potentiaUy take 100 years before the final cap is placed.
Stabilization of the trenches by natural subsidence over a relatively long time period would vinually
eliminate the potential of future subsidence problems encountered by alternatives that include me-
chanical stabilization of the trenches and installation of the final cap within a few yean. Therefore.
the natural stabilization alternative would reduce the redundancy of effons necessary to constlUCt
and maintain the final closure cap. NaruraJ stabilization does not disrupt intact metal containm such
as 55-gallon drums; therefore. radioactive material is not immediately added to the trench. This
containment provides an extta measure of proteCtion to prevent movement of radionuclides ro the
hillsides. An additional"benefit of the natural stabilization iJtenWive would be the opponunity for.
continued data colleCtion and analyses and evaluation of new teChnololies to optimize the final
closure. Thus, EPA has preliminarily identified Natural Stabilization {Alternative 5) as the prefemd
remedy for the Maxey flatS Disposal Site. Alternative 5 has four key phases as follows:
.
Initial Closure (22 months)
Interim Maintenance Period (35 - 100 yean)
Final Closure (10 months), and .
Custodial Maintenance Period (in perpetUity).
.
.
.
Each of the four key phases is described below.
Ininal CtoSUft!
This period would include a design phase fonowed by consuuction activities. Design of the initial
closure would be ~ormed and an Interim Site Management Plan developed for implementation
during the Interim Maintenance Period. .
During the Initial Closure Period. the fonowing remedial activities would be perfonned:
. Baseline Topographic Surveys
. Geophysical Survey .
. Subsidence MonitDrl .
. Ground Water MOnitorinl .
. Ground Wlter Modelinl .
. Initial Oosure Cap and Surface Water Manapment and ContrOl
. TreDCb I..adwe Management and Monitorinl
. Oosure of Selected Wells
. IDIaim Sire Management Plan .
. Maaitarina. Maintenance. and Surveillance
. Demolition of Existing Buildings and Strucmrcs With On-Sire Disposal, and
. Procurement of Buffer Zone Adjacent to the ExisUnI Sire Property.
Baseline tOpopaphic and leophysical surveys would be c:onducted priar rO deDp of the initi.a1
closure cap. Topopaphic surveys also would be performed prior to the initial closure ~ . installa-
tion. and foUowinl cap constrUCtion. The topolQiPhic surveys wouJd be used u baseline informa-
tion for subsidence monitOrinl- A jeophysical survey woWd enhance definition of trenCh bc>uncU-
ries and ensure dw the initial closure cap would adequately cover die trenChes.
19
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I
I
1,-
Subsidence monitors would ~e installed on the initial closure cap and on natural soils in the vicinity
of the Restricted Area as a method of determining when the ~nches have stabilized to an acceptable
degree and final closure can begin.
A ground water model would be developed and used. in conjunction with historical RI and Com-
monwealth data. to detennine the extent of the initial closure cap. evaluate the need for a horizontal
ground water flow barrier. and to develop an effective ground water monitoring plan for use during
the interim maintenance period and after closure. A ground water monitoring program would be
developed. based on the resultS of the model and on existing knowledge of ground water and con-
taminant flow. In addition. new monitoring wells would ~e installed. as appropriate. using the
resultS of the above evaluation. New monitoring wells also would be installed in the surrounding
stream valley alluvium to ensure compliance with drinking water standards.
Soil would be added to the site. graded. and compacted in preparation for installation of a synthetic
cover over the trench disposal area. (See next page for Cross-Section of Natural Stabilization.). The
initial layer would have an average thickness of 21 inches. The extent of the interim cover would be
, based upon geophysical surveys, ground water modelling and other parameterS evaluated during
design. It has been estimated that the interim cap would ,cover approximately 40 to SO acres. The
surface, would be graded'to design specifications for improved drainage. Lined drainage ditches'
would be installed to channel the surface water Nnoff to the three discharge basins. Additional
drainage channels in the vicinity of the site may be necessary to allow for increased control of the
rates of surface water runoff. Because of the high peak discharge volumes resulting from the initial
closure cap, the capacity of the retention ponds would be iricreased to improve control of stonn-
water runoff. '
Trenches would be de-watered ,to contrOl the migration of contaminantS by pound water flow. A
trench de-watering test program would be conductechither during the design phase or during initial '
closure activities to provide information on the most effective design of the de-watering program. to
detennine the need for new sumps, and to provide an estimate of the duration of the de-watering
program. Leachate pumped from the trenches would be solidified and buried in new trenches.
Existing, poorly designed wells could potentially allow contaminantS in ground water to migrate
downwird into the lower geologic unitS and would. therefore. be decommissioned and sealed.
Water monitoring equipment, as pan of the InfilU'ation Monitorinl System. would be installed in
trenches to detect the accumulation of leachate in trenches. '
. ,
Non-functional buildings and unstable buildings and structures would be dismantled and buried in a
trench on-site. Those buildings necessary to the managemene and maintenance of the site would be
, moved to a location thai would not impede remedial activities. These buildinp would then be
dismantled. as necessary. durinl fmal site closure~
Land would be purchased adjacent to the'existinl site propeny boundaries. The purchase of ~is
land would noc extend die currene site property boundary. alchoup control over the propertY pre-
sumably would be in die hands of the Commonwealrh of Kennac:ky. The purpose of I buffer zone :5
to protect en..iIonmenll11y sensitive areas such as the hill-slopes from detrimental activities such is
, loggina. and 111 allow unreslrieted access to areas adjac:ene co the MFDS for the purpose of monitor-
ing. ( See map 011 Pale 22 delineatinl buffer zone). Withoue control of ICIivities on the hill. slopes.
increased erosioa due to deforeswion could severely affect che effectiveness of che remedy. A I I
minimum. die buffer zone would extend from the currene site property boundary CD Drip SpnnIS. ~o
Name. and Rock Lick Creeks to the west, east, and souchwese ~f the sice. respectively.,
, '
, ,
A comprehensive Interim Site Manalement Plan would be developed durinl the design ~od to
define chemainrenance and monitOrinl wks to De conducced durinl the interim maintenance pcnod.
A monicorin,. maintenance. and surveillance proJI"IID would chen be implemented aI the site (oUo...
in, initial closure. as defined by the Interim Site Mana,emene Plan.,
20
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THICKNESS
-------
MFDS RESTRICTED
AREA
MFDS PROPERTY
BOUNDARY
PROPOSED BUFFER
ZONE
1AP PRODUCED BY E1A5CO SERVICES INCORPORATED AND -
POR THIS REPORT BY BOOZ. ALLEN & HAMILTON, ic
HAXEY FLATS DISPOSAL SlTE
PROPOSED BUFFER ZONE MAP
MAP 6
22
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Inrerim Mainrenance PeriQSt
Upo~ co~strUaion of the initial closure cap, the interi~ mai~tenance period would commence. The
Intenm Sue Management Plan would provide the basis for work activities during the interim mainte-'
nance period. During this period, the initial closure cap would continue to be maintained to prevent
infiltration of water into the trenches, maintenance of the site would continue, and the site would be
monitored by an enhanced monitoring/surveillance program. During the interim maintenance period
the following activities would be performed as prescribed by the Interim Site Management Plan:
.
Periodic Topographic Surveys and Subsidencc MonitOring
Ground Water Monitoring
Initial Closure Cap and Surface Wate~ Management and ContrOl
Trench Leachate Managcment and Monitorinl .
Monitoring, Maintenance, and Survcillance, and
Five Year Reviews.
.
.
.
.
.
The end of the interim maintenance ~od is defined as the rime when subsidence of the trenches
has nearly ceased and final closure begins. The criteria for final closure would be developed during
the design phase and could include acceptable void fraction, defined rate of minimal subsidence,
defined back-filling rate to maintain design grade, etC. The closure criteria would be dependant on
the design of the final closure cap and can be based upon engineerinl evaluations during thc dcvel-
opment of the Interim Site Management Plan. The primaJ'Y objective of the interim maintenance
period is to let the trenches stabilize by natural subsidence. Thus, the criteria would be dependant on
a minimal rate of subsidence and, when a final closure cap could be ,insWled without having to
repair it often due to continuing subsidence. .
TopolP'BPhic surveys and elevation surveys of'the subsidence moniron would be made periodiCally
to evaluate subsidence. This information would fann a database 10 be used to determine if the .
trenches have stabilized and the criteria for final closure have been achieved.
The initial closure cap would be inspected periodically to ensure that it has ROC failed and is cffec.
tively contrOlling surface water runoff. As needed. the cap would be repaired and synthetic lincr
replaced according to the Interim Site Management Plan. Cumndy, it is anUcipaleCi that the syn-
thetic liner would require replacement at 20-25 year interVals. Liner rep1Kement would be per-
formed in response to the liner condition and the manufactUrer's warrancy and specifications. The
specific liner type would be determined during development of the Interim Site Management Plan;
however, the liner would be of the type to require replacement no more often than the previously-
. stated ,20-25 year interVal. The drainale ditChes and retention ponds would also be cleaned and
maintained u needed. Erosion damage to the cap and drainale syStemS wouJd be repaired u
needed. ' .
The Infilcration Monirorin, System. installed to deteCt the lCCUIDuWion of leadwe in the.trenches.
would provide . wlmin, if le8chate began to accumulate in the aencha. This monitorin. syStem
would be used u. supplemau to the Commonwealth's current aench leachate monitOrinl prop-am.
Measures c:oaJd d8 be taken to eliminate the cause of the infilll'llioa. 11 sipUficant levels of
leacharc were cleJKled. die leacharc management p~ developed u pan of the Interim Site MJ.na gc-
ment PIaD, woaId be implemenleCi to remove, solidify, and dispose of the leachate. The resultS
would thea be ued to adjust the frequency of inspections. data collection. sample analyses. and
planned leaclwe pwnpin, and solidification.
Site monirorina. maintenance. and surveillance would be performed u dcftned by the Interim S I tC
Manqement Plan. Ground water samples would be collected periodically from specified. rmnJlor
wells for analysis and wuer levels taken. ..
Section 121(c) of CERa.A requires EPA to conduct a review of die remedy five years aJu:r llUca.
23
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tion of remedial action and once ~very five years thereafte~ for those remedial actions that allow
hazardous subStances to remain on-site. The purpose of thls review would be to evaluate the rem-
edy's Perfo~~ to ensure that it has achieved. or will achieve, the objectives set forth in. the
Record of DecISIon and is protective of human health and the environmenL If the remedy IS not
meeting-the defined remedial action objectives dUoring any of the five year reviews, or at any interim
point betWeen the five year reviews, or if the remedy fails to be protective of human health and the
environment,.a focused feasibility study would be conducted to detennine available technologies
that could be Imple~ented at the site to achieve the defined remedial action objectives and protec-
tion of human health and the environment. 0 . . .
During the first five year review, sufficient data should be available from the trench de-watering
program. information contained in the Commonwealth's historical leachate level database, Infiltra-
tion Monitoring System., ground water monitoring, and ground water modeling program to detennine
the necessity of a horizontal flow barrier. The decision to consauct a horizontal flow barrier would
be made by EPA, in consultation with the Commonwealth of Kentucky and industry expens. If
analysis of this data indicates that significant ground water is accumulating in the disposal trenches,
a horizontal flow barrier. would be installed to curta.il the ground water recharge. The location,
depth, and extent of this horizontal flow barrier would be determined through ground water model-
ing and review of site data.. o.
Two rypes of horizontal flow barriers were evaluated in the Feasibility Study. The type of horizontal
flow barrier installed at the sire, if needed, could include either the Nonh CutOff Wall or Lateral
Drain with CutOff Wall to encircle the trench disposal area.
Final Closure
When the resultS from the interim maintenance perjod monitoring show that the closure criteria have
been achieved. indicating that the trenches have sufficieRdy stabilized by nanaal subsidence, the
trenches would be capped by the final closure cap.. . .
The following ~tivities would be unde~en during final closure:
~
Waste Burial
Site Closure
Monitoring and Surveillance
Five Year Reviews
.
.
.
Any eontaminarcd or potentially contaminated materials at the site would be buried in a new trench.
These materials would include solidified leachare, lex hare stOl'ale tanks, and on-sire buildings
which would be demolished durin, final clo~ure.
The trenches would be covered by an engineered cap with synthedc liner and effective surface water
control sySteIDI would be insll1Jed ~ . limit infiltration. It is expected thai . sipUficant amount of
research daIa ad aew teClmolopcs win be developed duoupout dte incerim maintenanCe period.
ThUs.' the deli.. 01 me fiDa1 closure cap could refleCt the mosI advanced teChnololY for vertical
infiltmioa bmien.. . .
. .
A moniteriD.1Dd surveillance program would be implemented.. The propam would be funded in
~M~ .
CQstodial Maintenance Period
After the final closure cap has beenconmucted, a moniumnl pI'OJI'IID would be implemented a.t the
site. The frequency of monitoring aCtivities described for the in~ main~ ~od ~ou1d be
reduced durin, the posl-closure period due to the pres~ reducuon of water infilcranon 111[0 the
24
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trenches and reduced waste volume. This monitoring would be carried out in perpetuity..
Cg.u .
Cost analyses for Alternative 5 were based upon a discount rate of 4,5, 7 and l()4l, over a period of
100 years (the estimated time for which stabilization of the trenches is assumed to occur). This
Proposed Plan uses a discount rate of 4% for the alternatives, because it is the most conservative cost
.
figure.
EV ALUA nON Of AL TERNAnvES
Alternative I, the No ACtion alternative, would not comply with all Applicable or Relevant and
Appropriate RequirementS (ARARs) nor does it provide overall proteCtion of human health and the
environmenL Alternative 4, which includes a sauctural cap comprised of a tWo-fOOt layer of con-
crete and a tWo-foot layer of clay, provides shon- and lonl-term effectiveness relative to other
alternatives; however, it is difficult to implement and 15 nOt cost-effective. Alternative 8, which is
similar to Alternarive .5. except that a final multimedia cap is immediately insta1led over the trench.
disposal area. provides a lesser depee of lonl-tenn effectiveness and is far less COSt-effective than
Alternative.5. Alternative 17, which includes a 12-fooc thick enJinccred soil cap. is less protective. .
of public health and less cost effective than alternatives.5, 10 and 11. The remaininl three FS
alternatives (.5, 10. 11) differ in their approach toward achievinl aench stabilizalion.
Altematives.5 and 10 provide for (1) vertical infiltration barriers havinl permeabilities of 1 x 10"'
cm/sec or less. (2) aench leachate removal with disposal intO new crenc:hes. (3) a water management
system to prevent contamination of rainwater durinl consauction activities. (4) a horizontal flow
barner, if necessary. to prevent potential horizontal infilntion of pound water intO the trenches, (5)
environmental and performance monitorinl systems. and (6) an operuinl and maintenance aust ..
fund to ensure site cue in perpetuity~ Alternatives.5 and 10 differ principally in me means by which
they achieve lonl-tam site stability. Alternative 10 uses dynamic compaction to accelerate void
reduction to limit sipificant subsidence in the future. AlterlWiv.e.5. on the ocher hand. allows for
natural subsidence to occur by providinl for an interim aWntenaDCC period durinl which the site
would be araded aDd modified. to provide improved sunlCe runoff conditions. and covered by a
synthetic cover dw would prevent water from enterinl the trenChes aDd provides for ongoing repair
durinl &he IWIIrI1 aabiJizatian process. After subsidence hu .bared. a final cap would be installed
on the sire. Alr8nwiw 11 contains protective features similu to Alr.cnwiva 5 aDd 10, ex.cept that
compacliOli oldie IreDCbes is not included in this alternative. Grout would be injected intO the
trenches to .,.....em subsidence.
AltenWive .5 (Nuunl Stabilizuion) would achieve initial closure SOODCI' thu closure usinl other
altenWives; however. final closure would be implemenrect at a much later elate. With Alternative S,
proven tCChnoloaies would be used during initial closure; new tedmoloaies could be considered at
the time of final closure to tab advanrage of advances in research on low-level radioactive waste
sices. Major weaknesses of this alcenwive are the lactof app1icltiGa of ID i~..I~.~ Stabilization
tCCbnololY to the disposal crenches. However, this weakness is offset by maintaininl the integrity of
&he waste form. Other tCChnolopes could lead to increased release of ndionucl;dn without an
25
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.
I
alternative means to properly address migration from the dispoSal area.
. .
Ahernativ~ ~O (~namic Compaction) utilizes a, me~hanical method for significantly acceleratin,g
trench stabtlizaaon. Weaknesses of this altemauve ,"elude subsidence over trenches not dynanu-
cally compacted, minor subsidence over compacted Irenches due to continued deterioration of D"ench
waste. and the unproven natUre of this technology at the MFDS. In addition. this technology cur-
rently lacks community and state acceptance. at the MFDS. .
Alternati~e 11 (Trench Grouting) would achieve stab~lity ~sing the grouting technology that has
been apphed at low level radioactive waste disposal SItes. Including Maxey AatS. The technology
has not. however! been ap~lied at the scale require~ for s.tabili~tion of the entire site. The major
weaknesses of thIs alternanve are the implementabtltty ~ficulnes anticipated at the MFDS. and the
lack of a method for determining the location and magnItUde of voids before and after injecting
groUL Subsidence would also occur over trenches not grouted and minor subsidence over grouted
trenches due to continued deterioration of trench waste.
I
! . .
I
The Commonwealth endorses the use of natural stabilization for the Maxey RatS site. The Com-
monwealth considc;rs trench cover repair and a horizontal flow barrier, as needed, to be integral
features of the remedy to be chosen at the MFDS. . The.Commonwealth rejectS th~ u~ of Dynamic
Compaction (Alternative 10) for either a site demonstration or for tOtal site remediation due to .
"potential release of leachate to the environment. potential fractUring of the underlying geologic
strata. and lack of substantial information regarding trench waste location~ waste condition. and
waste contentS". The Commonwealth also rejectS grouting (Alternative II) for implementation at
Maxey AatS due to potentially unacceptable releases of leachate to the environment and the re- .
quired. timc-consuming demonstration .of this technology prior to implementation.
Community responses to the alternatives will be discussed in the Record of Decision which follows
the public comment period. Based on information currently available, EPA prefers Alternative 5.
Natural Stabilization, as me moSt acceptable remedy for me MFDS.This preliminary fmding was
reached after careful consideration of the technologies and remedial alternatives presented in the
Maxey flatS FS Repon and information contained in the Administl'llive Record. The prefetTed
alternative is believed to provide the best balance of trade-offs among alternatives, with respect to
the evaluation criteria.
FUTURE ACfIVITIES
EPA will hold a public meetinl on the preferred remedy for the MFDS on,June 13. 1991. This
meeting wiD give me public an opponunity to express their opinions and concerns about the pre-
ferred alternative and me o.mer alternatives considered. The meetinl also.will serve to begin a 60-
day public comment period. Due to me complexity of issues involvedo me number of documentS in
the Administrative Record, and the level of community involvement at me site,.EPA has granted a
30 day extension to me required minimum 3O-day public comment period on me preferred alterna-
tive. Therefore, a 6O-day public comment period will be heteL
. . .
, Issues raised by die pubtic during the public comment period will ~ addreSsed by me ,~A in a Re-
sponsiveness Summvy that becomes an official pan of the Agency s documented decisIon on the
remedy. The Record ofDccision is expected to be issued in late 1991. NeloGations betWeen Poten-
26
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tially Responsible Panies
-------
A public meed... is SCbeduled for 7:00 p.m09 June 13, 1991, and will be held at the Ersil P.
Ward (formerly known as Fox Valley) Elementary School in Aeminl County, Kentucky.
located onSwe Road 32, betWeen Morehead and Flemingsburg. -
EPA will summarize commentS and EPA's responses in the Responsiveness Summary section of
- the Record of Decision (ROD). To send written commenu or obtain funhcr information, contaCt:
Dave Kluesner
Site Project Manalv
Nortb Superfund Remedial Branch
- V.s. Environmental Protec:tloa Alellcy
345 Courtland Street, N.!.
- Atlanta. Geol'lia 30365
(404) 347.7791
~
MAILING LIST ADDmONS
If you did not receive this Proposed PIaiI by mail. or you know of others who wish to be
placed on the mailinllist far future publicalions perWnin. to this site, please fill out. detach
and mail this form to: -
5........-. DurIaam
Community ReJlaau CoardiIweJr.
Nanb S'4*fudd Branch9
U.S. EDYironmentll Proceaioa ApDCy.
345 Counlud ScneI. Adanll. OA 30365
Name
AddreIa
Afftli.ti(Ja
Telepbone
~;.
J,~-~
28
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~~::~Qj~~=~.
public: ac:cess to the material . . .'.'
Alluvium: Sedimem that has been deposited by rivers and stteams in COJDparaDvdyrecent tim&t
Aqwt8rd:: A subsurfice fomwioo of Jow permeability which minis &he mipmioa of pOUDd
~,.arertbmuah..~.~~~1 formations.. '. :. ..:?:.".,':::'..,: ':>.,':.":'.. ..
CompacdOD:" A ~~gned 10 inc:rase th~densirrof:~::I.ub~~,~~ '.
cC)~~;"'~~~~~~'Res~.cOD1~~U~'~~=::'~'(CuCu~' A. .
Federal.taw"passediD:1980"1Dd amended in 1986 by the SUpedimd~and.Re8IIthoriZl*
non Act(SA~);,.:1beActcreated a TruSt~ knowu~:~~!~::.~:~~lare and dem up
.a~~~~~::~ ~5UeSr ..' ""':.'::::::.;';:~::::>:":::;::::i:;:::::*:::::i;::f;(f::~i;:::.;;::ii'::::;;~:::}:'::',:,::,':",,'"
DecOmmisSfontoF"PteParadOns lakeu for reDM,nuclear (iiciUdCi'ftaai"ICdVe'~' The ~
jccrive'of decommisskmin&isto place th~ Cadlityin .such a ~~~.~risk to public-
==~7.:r::U:-:::~~-a~l1tndi'~ODi
a ~ scaIe'ror~, theetrecdVc Ibsorbed:do&'::,..It:"de~u'cbepmdDcl oltbc.. ..:: .
~~~lEf~~1IL~D.
. m:eptcr (ah~br.lCIIII1indMdiJa1);:PUfrit".l.atI&i]'~'.":~.iimXYiDl pouDd
wuer~.surface:~.1be8dll~~ IIId: faacl'eM.IM::;::'.~:.:~:imruaioD by bQ.
_in:=--::=::t:::rrJ:=:=-""~~=~
...~~1:JIiIit~
:hca . . _r_"'.'~:~~ ... 3O'A-.-..~'J"fiitJifA((:i_Balcbc.co- .
=dta'~:g''''''"'':::<':'':'::::':'.~:~:~l SOmC~'ffie~~~.~iDdiYidual =
29
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I.
drain. 1b~ cucoff wall would consist of an upper secti0l! o~ ~ clay or cement-mix and I
lo~ ~~ extending down to bedrock. or ceme~-rmx:. The purpose otthe horizonW flow
bame.r 15 to prevan the infilttarion of ground water lntO disposal tre11ches and the emItrauon of
leacbate ~:~e.ctisposal trenches. H
Hot Wel~~ ReC~'to wells at the Maxey Flats ~isposal ~itt. ~~ were used for the burial or small-
volume radioactive wastes with high specific act1vuy. Elght diStmCI weDs were consttucted
adjacent to one another, in what is refezred to historically as the "'hot well ueaw. Several other
wells were locat= apinst the walls of trenches. The \\fells in the "hot weu area" ~ 'Iemca!. 10
to 15 feet deep.l to 2 feet ii1 diameter. and were consuucted from coaaere, coated steelpi~ at
. til«?-H :ne~caPPCCfwi&h ODe large slab of ~., Otbc:r ~l1swem p1accd iD treDcbeI
~~f~~~E~pr=:~J~~---
rnforDiadoa RepositorY: .1\.1ibruy or other localioii when ~..~~ulDcld&~tdated. to a
S~nd piojecl'are;~llcedto ~Io~the public aa:ess!O Ibem.!aia~;: I:.or the Maxey FIats .
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H~~~==.!~:~;~p"ae:I~~t~=J:~
eff=ascmeroeDtP:(~~:qf'uni11ofX';'rayar a a~n...~tay ~.:RCIi:I.L1 die convezuional
unit~~~~~~:.:.::...:;.;::::( . i/ ... . . 'H. ....".. H,;:!::'.\;:::{:::.::.:;):::;:dt,;::;;:(ri.:D.:::'..;..:H .
. Ptc:o~ii::A~~=:I.I::.I:.~~;~~,~':ti::~::~:.il~=:~farradiolctivity.
It.~ ~~O:031:diiiD.. ...""'HOfa.ndiOliCUwICGlD 'ieah4Whidl: .. "ODe In me.
.. .....
30
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RemediallDYatflidoillFeasibility Study: A rwo-pan slUdy ofa ~ ~ site tbJtpro.
vides the buis:-se'-tiou of a remedial accion for the site. The first pan. or RL ~cUies me
nat~ IDd eateat.of'CCJrUaminarion. The second pan. or FS. idemifies and evallJltel ahematiYes
for addIessiDJ,Ji1e~. . '.
I . ":':':.'.'. '.' .
i Resource COa3ervatJOII and Recovery Act (RCRA): A Federal law dw emb1ished'. rep]a-
I tory system to track hazardous wasteS from the time of generarioa to disposal. 1k law lpecifies
I procedures to be used in creaDng. transporting, stonng, ~d disposing of hazardous wastes.
Restricted Area: An uea to which ac:c:ess is conaolled by the licezisee and timiUd to awbarized
~Mel to procect individuals from beiDa exposed to radiation andradi08Clive or chemical
nals. At the MfDS. this area is the fenced area that includes me burial umcbcs.. .
.SedimeDt: ~.~~~sett1e IDthe bouom of a~.~ 1::::,:;~.~~:.~ ofwucr.
SOUdiflcatfoa:,: ne Process by. which contaminanrs ~ ~'wida8: iWdemii, aPDt.1ib ~
ntenL... . . ,." ',' '. .'.;~ .:::. ":.:'" ..
.' . '. . '..". ".";.'.,"", "'. ,".'
. . ..., ..
. . Sump: An.ma lower than.tbe surrounding area used to CO~eCt Uq11iCls;.:: Ai the MFDS~ sUmp' lie
'pipes ~ the surfa= (0 me base of the trench where the p1peI' are slOtsI:ct. : They lie used 10
. collect. and pump leac~ce from the ttenche~ . . .' ...' "',.'" ',... :..."::. .' ."
SUl»'rfund ADlendments and Reauthorizatioa Act (SARA);:' A.Fedeiatllwpuaed in \986,;-
which modified the 1980 CERCLA Superfund law by sueDfIb~"IEPA~s'audaicy, Sra m;;,< .
volvemeut and opponunities Corpablic panicipaciolL AddiIioaaJ Superftmchevenacs II» were
granted. . '. "'. uu.'.u":::>;.;,,...., .
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31
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