United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R03-92/162
June 1992
&EPA Superfund
Record of Decision:
USA Aberdeen, Michaelsville,
MD
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NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement, but adds no further apnBcahle information to
the content of the document All supplemental material is, however, contained in the administrative record
for this site.
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50272-101
REPORT DOCUMENTATION i. REPORT NO. 2.
PAGE EPA/ROD/R03-92/162
4. TMesnd&uMIe
SUPERFUND RECORD OF DECISION
USA Aberdeen Michaelsville, MD
Second Remedial Action - Subsequent to follow
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U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
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06/30/92 ' i
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15.
PB93-963915
16. Atatact (Unite 200
The 20-acre USA Aberdeen Michaelsville Landfill is a municipal landfill located along
the Chesapeake Bay in Harford County, Maryland. The site is in the northern portion
of the Aberdeen Proving Ground (APG) in the Aberdeen Area (AA) between Michaelsville
Road and Trench Warfare Road. Land use in the area is predominantly industrial and
residential, with a wetland area located south and east of the site. In 1970,
operations at the landfill began and continued until its closure in 1980. Previous
studies of the landfill operations indicated that trench and fill methods were used to
dispose of wastes in the landfill. The majority of materials reportedly disposed of
at the site included domestic trash, trash from nonindustrial sources at APG,
solvents, waste motor oils, PCB transformer oils, wastewater treatment sludges,
pesticides containing thallium, insecticides containing selenium, and rodenticides
containing antimony. From 1981 to 1991, the county, state agencies, U.S. Army
Environmental Hygiene Agency (AEHA), and U.S. Army Corps of Engineers Waterways
Experiment Station (WES) periodically inspected the site. In 1981, the county
recommended that the landfill be capped. In 1983, the state inspected the installed
(See Attached Page)
17. Document AnaJysi* s. Descriptor*
Record of Decision - USA Aberdeen Michaelsville, MD
Second Remedial Action - Subsequent to follow
Contaminated Medium: Soil
Key Contaminants: Organics (pesticides), metals (chromium, lead)
b. Mentmera/Open'Ended Terme
c. COSAT1 Held/Group
18. AvMlibitty Statement
19. Security Qua (This Report)
None
20. Security Cliis (This Page)
None
21. No. ofPiges
62
22. Price
(See ANSW39.16)
See Instructions on Revene
OPTIONAL FORM 272 (*-77)
(Formerly NTIS-3S)
Department of Commerce
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EPA/ROD/R03-92/162
USA Aberdeen Michaelsville, MD
Second Remedial Action - Subsequent to follow
Abstract (Continued)
cover and advised the APG personnel to repair two "leachate outbreaks." In 1985, the
AEHA discovered that the landfill cover was not functioning properly and suggested that
an impervious cap be placed on the landfill. From 1987 to 1990, WES conducted an
analysis of ground water from the monitoring wells surrounding the site and concluded
that the landfill contributed chemicals to the uppermost aquifer. In early 1991, the
state observed several additional "leachate outbreaks" onsite. In mid-1991, a removal
action was conducted onsite by APG, which included installing a leachate collection
system to control and collect leachate. This ROD addresses protection of the ground
water by minimizing leachate flow and preventing current or future exposure to waste
materials as the first of two OUs planned for the site. A future ROD will address
sediment, surface water, and ground water at and near the site to determine the need, if
any, of further remediation at the site. The primary contaminants of concern affecting
the soil are organics, including organics including pesticides; and metals, including
chromium and lead.
The selected remedial action for this site includes replacing the existing cover with a
multi-layer cap in accordance with state requirements for sanitary landfills; covering
the cap with an earthen cover and revegetating the area; installing a methane gas venting
system within the cap system to minimize the migration or accumulation of gases generated
by the landfill wastes; and installing surface water controls to accommodate seasonal
precipitation. The present worth cost for this remedial action is $9,207,200, which
includes an annual O&M cost of $27,000 for 30 years.
PERFORMANCE STANDARDS OR GOALS: The soil clean-up goals for capping the site are
established in accordance with state requirements for sanitary landfill and RCRA subtitle
C requirements.
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RECORD OP DECISION
MICHAELSVILLE LANDFILL
Operable Unit One
U.S. Army Aberdeen Proving Ground, Maryland
DECLARATION
SITE NAME AND LOCATION
Michaelsville Landfill
Aberdeen Area
Aberdeen Proving Ground, Maryland
STATEMENT OF BASIS AMP PURPOSE
This decision document presents the selected remedial action for the
Michaelsville Landfill site. The selected remedial action was chosen in
accordance with the Comprehensive Environmental Response, Compensation and
Liability Act (CERCLA) of 1980, as amended by the Superfund Amendments and
Reauthorization Act (SARA) of 1986, and, to the extent practicable, the
National Oil and Hazardous Substances Pollution Contingency Plan (NCP).
This decision is based on the Administrative Record for this site.
The Environmental Protection Agency and the State of Maryland concur
on 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 (ROD), may present an imminent and substantial
endangerment to public health, welfare, or the environment.
DESCRIPTION OF THE REMEDY
This operable unit is the first of two operable units for the site.
This operable unit involves capping the landfill to prevent further
precipitation infiltration and subsequent leachate migration to the ground
water. The second operable unit will address other media to determine the
need, if any, of further remediation at the site.
The major components of the Selected Remedy include:
Installing a new, multilayered cap in accordance with MDE
requirements for sanitary landfill, using a geosynthetic
membrane. The design features of this system include a minimum
2 feet of compacted semipervious earthen material over the
existing landfill cover; a geosynthetic membrane (minimum
thickness 20 mil) over the earthen material; 12 inches of sand
drainage material embedded with perforated drainage pipes over
the membrane; and a final earthen cover (minimum 2 feet thick)
with a 4 percent minimum slope and vegetative stabilization;
Installing surface water controls to accommodate seasonal
precipitation; and
- Installing a methane gas venting system within the cap system.
STATUTORY DETERMINATIONS
The Selected Remedy is protective of human health and the environment
and is cost-effective. It also complies with Federal and State
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requirements that are legally applicable or relevant and appropriate to the
remedial action. This remedy utilizes permanent solutions and alternative
treatment technologies to the maximum extent practicable for this site.
However, because treatment of the principal threats of the site was not
found to be practicable, this remedy does not satisfy the statutory
preference for treatment as a principal element of the remedy. The size of
the landfill, excessive costs associated with the excavation alternatives,
and the difficulties of implementing the excavation alternatives preclude
a remedy in which contaminants could be excavated and treated effectively.
The Selected Remedy is consistent with the Superfund program policy of
containment, rather than treatment, for wastes that do not represent a
principal threat at the site and are not highly toxic or mobile in the
environment.
Because the Selected Remedy will result in hazardous substances
remaining on-site above health-based levels, a review under Section 121(c)
of CERCLA, 42 U.S.C. S 9621(c), will be conducted within five years after
the commencement of remedial action to ensure that the remedy continues to
provide adequate protection of human health and the environment.
Data7 >*^ Ronald V. Hite
^ Major General, U.S. Army
Commanding
Aberdeen Proving Ground
Date Lewis D. Walker
Deputy Assistant Secretary of the
Army for Environment, Safety,
and Occupational Health
U.S. Department of the Army
J~
Dace / Edwin B. Erickson
Regional Administrator
U.S. Environmental Protection Agency
Region ill
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RECORD OF DECISION
MICHAELSVILLE LANDFILL
Operable Unit One
U.S. Army Aberdeen Proving Ground/ Maryland
DECISION SUMMARY
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TABLE OP CONTENTS
Section Page
I. SITE MAKE, LOCATION, AND DESCRIPTION 1
General 1
MLF Geology 1
MLF Surface Water 5
MLF Ground Water 5
MLF Climatology 6
MLF Land Use 6
MLF Flora and Fauna 8
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES 10
History of Site Activities 10
History of Investigations/Remedial Actions 10
Enforcement Activities 11
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION 11
IV. SCOPE AND ROLE OP OPERABLE UNIT 12
V. SUMMARY OP SITE CHARACTERISTICS 13
MLF Soil 13
MLF Ground Water 15
MLF Seeps 19
MLF Surface Water 21
Air 23
VI. SUMMARY OF SITE RISKS 23
VII. DESCRIPTION OP ALTERNATIVES 31
VIII. SUMMARY OP COMPARATIVE ANALYSIS OP ALTERNATIVES. . 31
Overall Protection of Human Health and the Environment 35
Compliance With ARARs 36
Long-Term Effectiveness 43
Reduction of Toxicity, Mobility, and Volume 44
Short-Terra Effectiveness 45
Implement ability 45
Cost 46
Support Agency Acceptance 46
Community Acceptance 47
IX. DESCRIPTION OP THE SELECTED REMEDY 47
Z. STATUATORY DETERMINATIONS 51
Protection of Human Health and the Environment 51
Compliance With Applicable or Relevant and
Appropriate Requirements 52
Cost-Effectiveness 52
Utilization of Permanent Solutions and Alternative
Treatment (or Resource Recovery) Technologies to the
Maximum Extent Practicable (MEP) 52
Preference for Treatment as a Principal Element 55
Documentation of Significant Changes 56
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TABLE OF CONTENTS
(Continued)
Section Page
ZZ. RESPOHSXVENESS SUMMARY 56
Overview 56
Background on Community Involvement 57
Summary of Comments Received During The Public
Comment Period and Agency Responses 57
REFERENCES
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LIST OF FIGURES
Figure Page
1 Aberdeen Proving Ground Regional Location Map 2
2 Location of Michaelsville Landfill on Aberdeen
Proving Ground-Aberdeen Area 3
3 Michaelsville Landfill Site Map 4
4 Monitoring Well Locations at Michaelsville
Landfill Site 7
5 Habitat Characteristics of Michaelsville Landfill Area 9
6 Typical Cross-Section for Alternative 5 MDE Cap Utilizing
a Synthetic Geotnembrane 48
LIST OF TABLES
Table Page
1 Summary of Chemicals Detected in Surface Soil at
Michaelsville Landfill 14
2 Summary of Chemicals Detected in Shallow Ground
Water at Michaelsville Landfill 16
3 Summary of Chemicals Detected in Deep Ground
Water at Michaelsville Landfill 18
4 Summary of Chemicals Detected in Seeps at
Michaelsville Landfill 20
5 Summary of Chemicals Detected in Surface Water
at Michaelsville Landfill 22
6 Michaelsville Landfill Gas Monitoring Well
Sampling Results, February 1989 24
7 Michaelsville Landfill Gas Monitoring Well
Sampling Results, March 1989 25
8 Michaelsville Landfill Gas Monitoring Well
Sampling Results, April 1989 26
9 Potential Risk Associated With Hypothetical
Future Ingestion of Shallow Ground Water at
Michaelsville Landfill 29
10 Summary of Capping Alternatives 32
11 Summary of Excavation Alternatives 34
12 Review of Potential Action-Specific and Locational
ARARs For Michaelsville Landfill Remedial Action
Alternatives 37
13 Cost Estimate For Alternative 5 MOB Sanitary
Landfill Cap Utilizing Synthetic Geomembrane at
Michaelsville Landfill 49
14 Review of Potential Action-Specific and Locational
ARARs for Michaelsville Landfill Selected Remedy 53
iii
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RECORD OF DECISION
MICHAELSVILLE LANDFILL, ABERDEEN PROVING GROUND
DECISION SUMMARY
I. SITE NAME. LOCATION. AND DESCRIPTION
As shown in Figure 1, Aberdeen Proving Ground (APG) is located along
the Chesapeake Bay in Harford County, Maryland, approximately 15 miles
northeast of the city of Baltimore. The Michaelsville Landfill (MLF) is
located in the northern portion of APG in the Aberdeen Area (AA) between
Michaelsville Road and Trench Warfare Road.
General
MLF is located in the north-central portion of APG-AA (Figure 2).
Figure 3 provides an illustration of MLF. MLF is an approximately 20-acre,
unlined municipal-type landfill characterized by two small, mounded areas,
one near the northeast end of the landfill and the second near the center
of the landfill (Figure 3). Elevations on the landfill range between 28
and 46 feet above mean sea level (msl). The waste in the landfill is
buried to a depth of approximately 10 feet below the original ground
surface elevation and is mounded to a height approximately 16 feet above
the original ground surface elevation. Two low-lying areas and a pond are
located adjacent to the southwestern edge of the landfill. The
northeastern end of MLF (approximately 5 acres) is covered with grass; the
remainder of the landfill is covered with small trees, shrubs, and tall
grass. Many erosional rills and gullies cut the southern end of the
landfill, and seeps occur around the perimeter of the landfill during rainy
periods. Several drainage ditches around the landfill receive runoff from
these seeps and other nearby areas (Figure 3).
MLF Geology
The general stratigraphy at APG-AA is based on an exploratory boring
(777 feet deep) on Spesutie Island (Figure 2). The upper 85 feet of
sediment, which is a medium to coarse sand overlying a brown silt that
overlies fine to coarse sand, gravel, and some cobbles, has been defined as
the Talbot Formation. The Talbot unconformably overlies the Potomac Group
at an elevation of -73 feet mean sea level (msl). A break between the
Patapsco Formation and the underlying Arundel Formation was estimated to be
at an elevation of -403 feet msl. The Arundel Formation and the underlying
Patuxent Formation were not differentiated. Bedrock was encountered at an
elevation of -748 feet msl.
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^MARYLAND \ "T"
kJ£r BdAir
° ABERDEEN
BALTIMORE COUNTY
«*
\ PROVING
QUEEN ANNE'S
COUNTY
ANNE ARUNDEL
COUNTY
Annapolis
nGUREl
ABERDEEN PROVING GROUND
REGIONAL LOCATION MAP
10 Mitt*
SCALE
SOURCE: WES, 1990
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SWAN CREEK
RESERVATION BOUNDARY
MICHAELSVILLE ^ ^n
LANDFILL DRMO SCRAP
METAL YARDfDIPPEa CREEK
Spesutie Island
LEGEND:
MICHAELSVILLE LANDFILL
DRMO SCRAP METAL YARD
6000
SCALE
10.000 Feel
FIGURE 2
LOCATION OF MICHAELSVILLE LANDFILL
ABERDEEN PROVING GROUND
ABERDEEN AREA
SOURCE: WES, 1990
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.
LEGEND:
46I
TOPOGRAPHY CONTOURS
TOWER
-^BUILDING
287
PERIMETER
. OF LANDFILL
TRENCH WARFARE ROAD
FIGURE 3
MICHAULSVILLE LANDFILL
SITEMAP
SOURCE ICF. 1991
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A silty clay layer ranging in thickness from 5 to 16 feet is
consistently found over the surface of the MLF site (WES, 1990). The
landfill waste material is reported to be within the silty clay, extending
to an average depth of 6 feet below original grade. Underlying the silty
clay layer are 20 to 30 feet of depositional layers of gravel and sand with
clay lenses in some areas. This gravel and sand layer is considered the
uppermost aquifer and varies from a water table aquifer to a confined
aquifer. Underlying the gravel and sand layer are 50 to 65 feet of
interbedded clays, silts, and sands that act together as an aquitard. In
the eastern portion of the site, there are two sand layers within the
interbedded clays, silts, and sands, which are possible minor aquifers.
Underlying the interbedded clays, silts and sands is the lower sand
aquifer, an approximately 30-foot-thick, fine-grained, carbonaceous sand
layer. Underlying the sand layer is an approximately 10-foot-thick layer
of interlaminated brown, organic clays, silts, and fine-grained sands.
The base of the aquifer unit beneath MLF is defined by a consistent, hard,
waxy, clay aquiclude layer found at depths of -85 feet msl in the northern
part of the site and -100 feet msl in the southern part.
MLF Surface Water
MLF is not within the 100-year flood area. The nearest 100-year flood
area is approximately 1 mile east of MLF along Woodcrest Creek (FEMA,
1983). Multiple erosional rills and gullies cut the southern edge of the
landfill and several seeps are located around the perimeter. Flow from the
seeps is intermittent, depending on rainfall. Flow from seeps generally
drains into nearby drainage ditches (Figure 3). One of the drainage
ditches at MLF flows into the northeastern edge of the property and south
along MLF until it merges with the drainage ditch which intercepts seeps
from the southern edge of the landfill (ICF, 1991). Low areas around MLF
become temporarily inundated during heavy rainfalls. Two low-lying areas
and a pond are located adjacent to the southwest portion of the landfill.
MLF is located in the Roraney Creek watershed (ICF, 1991).
Qro"r|d Water
Two aquifers, identified as the uppermost aquifer and the lower
aquifer have been studied at MLF (WES, 1990). The uppermost aquifer is
located beneath the surficial silty clay layer and has a base 30 to 40 feet
deep on the aquitard of interbedded clays, silts and sands. Ground water
elevation in the uppermost aquifer ranges from 20 to 25 feet msl, which is
approximately 5 to 10 feet below the ground surface surrounding MLF.
The lower aquifer is beneath the aquitard and above the consistent
clay found at -85 to -100 feet msl. Borings are extending into this clay
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for 20 to 65 feet. The poteritimetric level in the lower aquifer is
consistently two to three feet below the ground water elevations of the
uppermost aquifer.
Regional ground water movement is generally southeast towards the
Chesapeake Bay. Water elevations from the shallow WES wells were used to
contour the water table in 1988 and 1989. Although the predominant flow
direction in the upper aquifer was to the Trench Warfare Road side of the
landfill, several flow reversals were noted and it appears that the
landfill and surrounding recharge areas may be locally affecting flow. The
major component of flow in the lower confined aquifer is to the south-
southwest (WES, 1990).
The City of Aberdeen production wells northwest of MLF utilize the
uppermost aquifer and the Harford County production wells southwest of MLF
utilize both the uppermost and lower aquifer. The City of Aberdeen
production wells are upgradient of MLF ground water flow and the Harford
County production wells are crossgradient from MLF ground water flow.
MLF Climatology
Due to the proximity of two large bodies of water, the Chesapeake Bay
and the Atlantic Ocean, the climate in the APG area tends to be moderate as
compared to the inland areas (ESE, 1981). The average annual temperature
is 54.5 degrees Fahrenheit (°F), with an average relative humidity of 73.8
percent. Precipitation averaged 44.8 inches (in.) per year over the last
21 years, with the maximum rainfall occurring in the summer and the minimum
during the winter (WES, 1990). Precipitation as snowfall averages 12 in.
per year (Sisson, 1985). Prevailing winds average 6.8 knots (Sisson, 1985)
in a northwest to north-northwest direction in the winter months and a
south to south-southwest direction in the summer months (ESE, 1981).
MLF Land Use
MLF has been closed since the December of 1980. APG-AA is a fenced,
controlled area and access to MLF is restricted. The landfill itself is
not fenced, and there are no ,control measures to prevent access once
personnel are within the controlled area.
The landfill itself had been capped with a 0 to 2-foot thick layer of
compacted earthen material. Ground water monitoring wells are located
around the landfill (as can be seen in Figure 4). A series of gas vents
has also been installed. In addition, a seep drainage system serves to
collect leachate seepage and contain it for removal off-site. These
features will be discussed in more detail in the following section.
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BUILDING M714
LEGEND:
WES Ground Water Monitoring Welts
O USAGE Ground Water Monitoring Wells
A WES Gas Monitoring Wells
WES MS
WES M-6
WES M-7
WES M 2
WES M 3
WES M 4
WESM-18
WESM-19
WES
AG-4
PERIMETER
OF LANDFILL
QMW-16
AG-S
480ft
Approximate Scale
FIGURE 4
MONITORING WELL LOCATIONS
AT MICHAELSVILLE LANDFILL SITE
A
G6
SOURCE: WES. 1990
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The main industrial sector of APG-AA is approximately 3,300 feet north
of MLF. Several operations are situated around the landfill. A large
firing range is located immediately south and east of the landfill. Firing
is parallel to the landfill, and observation towers are located on Trench
Warfare Road near each end of the landfill. An ammunition receiving and
shipping building is located approximately 500 feet west of the landfill;
most of the landfill is located within the 1,800-foot safety clearance
range of the ammunition receiving and shipping building. An unused
concrete observation tower is located approximately 150 feet northeast of
the landfill, and a pistol range is located approximately 1,500 feet north
of the landfill (ICF, 1991). The Defense Reutilization and Marketing
Office (DRMO) scrap metal yard is located approximately 1,300 feet
northeast of the landfill (as can be seen in Figure 2).
APG barracks are located approximately 1 mile north of the landfill,
and on-post family housing is located about 2 miles north of the landfill.
The City of Aberdeen is approximately 4 miles north of the landfill, and
the City of Ferryman is approximately 1.75 miles west of the landfill. All
of these residential areas are outside of the fenced, controlled area of
the AA (ICF, 1991).
MLF Flora and Fauna
Wetlands habitat characteristics of MLF and the surrounding area are
shown in Figure 5. The northern part of the site is covered with grass.
The southern portion is covered with grass, shrubs, and small trees one to
ten feet high. A pond is located near the southwestern part of the
landfill. A drainage ditch runs along the southeastern edge of the
landfill and connects with another drainage ditch, which intercepts the
seeps from the southern edge of the landfill (Figure 3). Romney Creek is
located south and east of the site, and a wetland area is located around
Romney Creek (ICF, 1991).
Terrestrial wildlife in the area of the landfill probably includes
song birds, rabbits, and field mice. In addition, the bald eagle, an
endangered species known to be present at APG, could spend some time in the
landfill area. Small ahorebirds may frequent the ditch and the pond.
Raccoons may also use these areas. Aquatic invertebrates and amphibians
may be present in the drainage ditch along the southern edge of the
landfill and in the pond. Fish may also be present in the ditch, but
significant fish populations are not expected to be present. Water flow in
the seeps is intermittent and dependent on rainfall; thus, the diversity
and abundance of aquatic life in the seeps is expected to be limited (ICF,
1991)./
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Bara Earth. Mowed or
Developed Land
Wafland
SOURCE: ICF. 1991
FIGURE 5
HABITAT CHARACTERISTICS OF
MICHAELSVILLE LANDFILL AREA
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Aa noted in Figure 5, areas in the northern corner of the landfill and
adjacent to the southwestern corner of the landfill are considered
wetlands. The combined areal extent of these locations is estimated to be
2.5 acres.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
History of Site Activities
Operations at MLF began about 1970 and continued until its closure in
1980. Previous studies of the landfill operations indicate that trench and
fill methods were used to dispose of wastes in the landfill. Wastes were
covered with soil and compacted with a bulldozer. The majority of
materials reportedly disposed of in MLF were domestic trash and trash from
non-induatrial sources at APG. Other materials that reportedly may have
been disposed of in limited quantities include solvents, waste motor oils,
polychlorinated biphenyl (PCB) transformer oils, wastewater treatment
sludges, pesticides containing thallium, insecticides containing selenium,
and rodenticides containing antimony.
History of Investigations/Remedial Actions
After MLF was closed in 1980, the landfill cap's condition was
inspected by the Harford County Department of Health in 1981, the State of
Maryland Department of Health and Mental Hygiene (DHMH) in 1983, the U.S.
Army Environmental Hygiene Agency (AEHA) in 1985, the U.S. Army Corps of
Engineers Waterways Experiment Station (WES) in 1987 through 1990, and the
Maryland Department of the Environment (MDE) in 1991.
The 1981 inspection of MLF by the Harford County Department of Health
recommended that the landfill be capped with a minimum of 2 feet of
relatively impermeable material and covered with topsoil. In 1983, the
State of Maryland DHMH inspected the landfill after some work had been
accomplished at the site. The DHMH representative advised APG personnel
that the cover was satisfactory with the exception of two "leachate
outbreaks" that APG personnel were instructed to repair. In 1985, AEHA
personnel observed the landfill and noted that the "cap and cover do not
appear to be functioning adequately." AEHA recommended that an impervious
cap be placed on the landfill with adequate compaction and sloping.
The MLF investigation by WES from 1987 through 1990 included the
installation of ground water monitoring wells and the collection and
analysis ground water, surface water, seepage water, soil, and air
samples. ^e draft Hydrogeologic Assessment (HGA) report prepared by WES
concluded that, according to analysis of ground water from the monitoring
10
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wells surrounding MLF, the landfill is contributing chemicals to the
uppermost aquifer (WES, 1990). This reportedly occurs primarily along the
southeast side of the landfill, on the ends of the landfill, and
immediately northwest of the landfill. Parameters detected in the ground
water included a number of organic and inorganic contaminants which were
evaluated by ICF (1991) in the Preliminary Risk Assessment (PRA) and which
will be discussed in subsequent sections.
MDE representatives visited MLF in January, March, and April 1991.
During these site visits, MOE representatives observed "leachate outbreaks"
at several locations on MLF. Observation reports written by MDE personnel
during these site visits suggested that capping the landfill could prevent
these leachate outbreaks from continuing.
In June and July 1991, under the Installation Restoration Program, a
removal action was conducted at MLF involving the installation of a.
leachate collection system to control and collect leachate. The collection
system consists of a network of subsurface drains that extend to identified
seep areas and collect leachate for transfer to sumps along the east side
of the landfill. The leachate is automatically pumped from the sumps to
nearby holding tanks. The holding tanks are periodically emptied and the
leachate disposed through APG's sewage treatment plant.
Enforcement Activities
In April 1985, the U.S. Environmental Protection Agency (EPA)
published a Federal Register notice which proposed MLF for inclusion on the
National Priorities List (NPL). MLF was listed on the NPL on October 4,
1989. Pursuant to Section 120 of the Comprehensive Environmental Response,
Compensation and Liability Act (CERCLA), 42 U.S.C. § 9620, the U.S. Army
and EPA signed a Federal Facility Agreement (FFA) in March 1990 which
provides for the oversight and enforcement of environmental investigations
and remedial actions at selected APG study areas. MLF is one of the APG
study areas specified in the FFA.
III. HIGWT-IGHTS Qp COMMUNITY PARTICIPATION
The HGA (WES, 1990), Focused Feasibility Study (FFS) (Dames & Moore,
1991a), Proposed Remedial Action Plan (Dames & Moore, 1992), and background
documentation for MLF were released to the public for comment on March 18,
1992. These documents were made available to the public in the local
information and administrative record repository at the Aberdeen and
Edgewood Public Libraries. The notice of availability of these documents
was published in the March 18, 1992 issue of the Aegis and The Sun
newspapers, and in the April 5, 1992 issue of the Harford County Sun. A
11
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public comment period on the documents was held from March 18, 1992 to May
4, 1992. Additionally, a public meeting was held on April 9, 1992 at the
Aberdeen Area Chapel, APG. At this meeting, representatives from the U.S.
Army, EPA, and the MDE answered questions about MLF and the cap and cover
system remedial alternatives under consideration. Responses to comments
received during this period are included in the Responsiveness Summary,
which is part of this Record of Decision (ROD). The Responsiveness Summary
is based on oral and written comments received during the public comment
period. The above actions satisfy the requirements of Sections 113(k) and
117 of CERCLA, 42 U.S.C. §S 9613(k) and 9617. The decision for this site
is based on the administrative record.
IV. SCOPE AND ROLE OF OPERABLE UNIT
The Army has organized the work at MLF into two operable units (OUs)
which are as follows:
OU One: Source of Contamination.
OU Two: Ground water contamination.
The first OU authorized by this ROD addresses MLF's source of
contamination. Infiltration of precipitation could result in migration of
contaminants to the ground water and thus the landfill poses a potential
risk to human health and the environment. The landfill poses a potential
risk to human health and the environment because of the potential for
precipitation to infiltrate the waste and mobilize contaminants which could
migrate to the ground water, posing a potential risk due to ingestion of
the ground water. In addition, the landfill presents a potential for
dermal contact with waste materials and inhalation of airborne
contaminants. The purpose of this response is to minimize leachate flow to
the ground water and to prevent current or future exposure to the waste
material via dermal contact or inhalation of airborne contaminants.
The Army has already begun to address the second OU through the
conduct of a Remedial Investigation and Feasibility Study (RI/FS) of the
sediment, surface water and ground water at and near MLF (WES, 1991). The
RI/FS for the second operable unit will continue with the installation of
additional wells and sampling as described in the RI/FS Work Plan (WES,
1991) if the Work Plan is approved by EPA and concurred by MDE. The RI/FS
will determine if remedial action is necessary to further mitigate the
potential spread of contaminants from the landfill.
12
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V. SUMMARY OF SITE CHARACTERISTICS
The source of contamination at MLF i3 the waste in the landfill
itself. By far the majority of materials placed in MLF was domestic trash
and trash from non-industrial operations at APG. The remaining portion of
the waste included sludges from the waste water treatment plant, pesticide
containers, rabbit droppings, swimming pool paint, old asbestos shingles,
solvents, waste motor oils, grease, and PCS transformer oils (WES, 1990).
In addition, pesticides containing thallium, insecticides containing
selenium, and rodenticides containing antimony may have been placed in MLF
in limited quantities.
MLP Soil
In October 1989, two surface soil samples were collected by WES from
the top of the landfill as a part of the May 1990 draft HGA (WES, 1990).
Because the landfill is covered with what is presumed to be clean fill,
these samples were not believed to be representative of landfill
contamination (ICF, 1991). Two other soil samples were collected by WES
approximately 700 feet east of the landfill to serve as "background"
samples. Although the two background samples help to characterize levels
of chemicals in nearby areas (out of the fill area), they may not be
representative of "natural" background because they were collected from
sites located between the DRMO scrap metal yard and the landfill, an area
that would not be expected to be unaffected by human activities (ICF,
1991). Soil samples were analyzed for volatile organic compounds,
semivolatile organic compounds, pesticides, PCBs, and inorganic chemicals.
Constituents detected in MLF surface soil are shown in Table 1.
Organic chemicals detected were acetone, methylene chloride, and several
pesticides. With the exception of acetone, all organic chemicals detected
in these samples were detected in the background samples at similar levels.
This may mean that their presence in cover soils is indicative of general
area contamination (perhaps from pesticide usage) that may or may not be
related to landfill operations. Methylene chloride, which was also present
in the soil blank, is a common laboratory contaminant, and therefore may
not actually be present in the landfill cover soils. Acetone, also a
common laboratory contaminant, was not present in the soil blanks (WES,
1990).
Of the inorganic chemicals detected in landfill soils, the maximum
concentrations of chromium, copper, and zinc were present at levels only
slightly above the maximum concentration detected in background samples.
The potential routes of exposure to contaminants found in soils at MLF
include dermal contact, inhalation of airborne dusts, leaching of soil
13
-------
TABLE 1
SUMMARY OF CHEMICALS DETECTED IN
SURFACE SOIL AT MICHAELSVILLE LANDFILL (a)
(Concentrations reported in ug/kg for organic, and in mg/kg for inorganics)
Chemical (b)
Frequency of
Detection (e)
Range of Detected
Concentrations
Rang* of Background
Concentrations (d)
Organic Chemicals:
' Acetone (ACET)
' DDT (total)
4.4--DDD (PPDDD)
4,4'-DDE (PPDDE)
4,4'-DDT (PPDDT)
' Endosulfau Sulfate (ESFS04)
' Endrin Aldehyde (ENDRNA)
' Heptachlor (HPCL)
' Heptachlor Eporide (HPCT.E)
' Methylene Chloride (CH2CL2)
1/2
1/1
1/1
1/1
1/1
1/1
1/1
2/2
1/1
2/2
41,000
14.0
7.00
3.00
4.00
6.00
13.0
1.00 - 11.0
ZOO
170 - 810
ND
6.00 -117
1.00 - 10.0
5.00 - 44.0
63.0
1.00 - 2.00
1.00
1.00 - 2.00
1.00
1,000 - 1,400
Inorganic Chemicals:
Cadmium (CD)
Chromium (CR)
Copper (CU)
Lead (PB)
Nickel (NT)
Thallium (TL)
' Zinc (ZN)
2/2
2/2
2/2
2/2
2/2
2/2
2/2
0.200 - 0.500
18.0 - 19.7
8.40-1ZS
15.0 - 25.2
10.3 - 11.6
0.100 - 0300
41.8 - 44.4
0.300 - 0.900
8.40 - 16.0
6.40 - 8.50
25.9 - 31.1
5.00 - 11.7
0.200 - 0300
28.8-41.1
(a) Samples MVSOIL-1 and MVSOIL-2
(b) USATHAMA chemical codes listed in parentheses.
(c) The number of sample* in which chemical was detected divided by the total number of
samples analyzed for that chemical.
(d) Samples: MVBG-l and MVBG-2.
ND
Selected as a chemical of potential concern. Sec text.
' Not detected.
SOURCE: ICF, PRELIMINARY RISK ASSESSMENT, 199L
14
-------
contamination to ground water during precipitation events, and transport of
soil contamination by runoff to surface water. Because the site is located
in a secure military installation to which access is limited, the
likelihood of exposure through dermal contact is relatively low.
MLF Ground Water
A total of 33 ground water wells have been installed around MLF during
previous investigations, including eight installed by USAGE and 25
installed by WES. The eight USAGE wells were sampled in January and
September 1988, 24 of 25 WES wells were sampled in September 1988, 22 of 25
WES wells were sampled in December 1989, and all 25 WES wells were sampled
in April 1989. Shallow well WES-M-15 was also sampled on June 2, 1988
(WES, 1990). Figure 5 provides the locations of all wells at MLF.
Ground water samples were analyzed for volatile organic compounds,
semi-volatile organic compounds, pesticides, PCBs, and dissolved inorganic
chemicals. In addition, the ground water sample collected from shallow
well WES-M-15 on June 2, 1988, was analyzed for explosive compounds (WES,
1990).
The chemicals detected in these sampling rounds from the shallow and
deep ground water wells at MLF are shown in Tables 2 and 3, respectively.
Thirty organic chemicals were detected in shallow ground water (WES, 1990).
About half of these chemicals were, however, detected in fewer than 10
percent of the samples and at low concentrations. The predominant organic
groups present in this ground water were pesticides, phthalate esters, and
chlorinated aliphatics. Methylene chloride was the most frequently
detected chemical. PCBs were also detected relatively frequently but at
very low levels (less than 1 microgram per liter (pg/L)). It should be
noted that several phthalates, many pesticides, PCBs (Araclor-1254), and
ammonia nitrogen were also detected in blank samples during these sampling
events (except for January 1988, when no blank samples were collected; WES,
1990). Deep ground water showed fewer organic chemicals, but a similar
array at generally lower concentrations. Acetone was an exception because
it was present at much higher concentrations in deep ground water; it was
detected in one of 28 samples in shallow ground water at a concentration of
70 A/g/L and in two of five samples at a maximum concentration of 2,310 pg/L
in deep ground water (WES, 1990).
Several inorganic chemicals were identified as being potentially
elevated above background levels in both shallow and deep ground water.
However, no site-specific or regional ground water background data were
available with which to compare site levels. Several inorganic chemicals
were also detected in blank samples (WES, 1990).
15
-------
TABLE 2
SUMMARY OF CHEMICALS DETECTED IN SHALLOW
GROUND WATER AT MICHAELSVILLE LANDFILL (a)
(Concentrations reported in ug/L)
Chemical (b)
Frequency of
Detection (c)
Range of Detected
Concentrations (d)
Range of Background
Concentrations (e)
Organic Chemicals
Acetone (ACET)
Aldrin (ALDRN)
Benzene (C6H6)
alpha-BHC (ABHC)
beta-BHC (BBHC)
delta-BHC (DBHQ
Butylbenzylphthalate (BBZP)
Chloroethane (C2H5CL)
Chloroform (CHCL3)
DDT [Total]
* 4,4'-DDD (PPDDD)
4,4'-DDT (PPDDT)
* Dibutylphthalate (DNPH)
1,1-Dichloroethane (11DCL)
1,2-Dichloroethane (12DCLE)
cis-l,2-Dichloroethene (C12DCE)
* trans-l,2-Dichloroethene (T12DCE)
Dieldrin (DLDRN)
Diethylphthalate (DEP)
2,4-Dimethylphenol (24DMPN)
* 1,3-Dinitrobenzene (13DNB) (0
Di-n-octylphthalate (DNOP)
1,2-Diphenylhydrazine (12DPH)
Endosulfan I (AENSLF)
Endosulfan II (BENSLF)
* Endosulfan Sulfate (ESFS04)
bis(2-Ethyl(hexy1)phthalate (B2EHP)
* Heptachlor (HPCL)
* Heptachlor Eporide (HPCLE)
Methylene Chloride (CH2CL2)
' PCBs (g)
Inorganic Chemicals:
* Ammonia Nitrogen (NH3N2)
Antimony (SB)
Arsenic (AS)
Beryllium (BE)
Cadmium (CD)
Calcium (CA)
Chloride (CL)
Chromium (CR)
Copper (CU)
* Iron (FE)
Lead (PB)
Magnesium (MG)
Manganese (MN)
Nickel (NI)
Nitrate (NO3)
Orthophosphate (P040RT)
Potassium (K)
Selenium (SE)
Sodium (NA)
Sulfate (SO4)
Thallium (TL)
Zinc(ZN)
1/28
2/28
1/28
2/28
1/28
1/28
20/28
3/28
1/28
12/28
1/28
12/28
20/28
2/28
2/28
6/28
1/28
6/28
12/28
1/27
1/1
20/28
1/28
8/28
2/28
2/28
28/28
19/28
7/28
21/28
13/28
28/28
24/28
7/28
3/28
27/28
8/8
28/28
21/28
26/28
27/27
24/28
8/8
8/8
28/28
28/28
28/28
8/8
16/28
8/8
28/28
13/28
28/28
70.0
0.0100
3.40
0.0100
0.0100
0.0200
4.00 - 17.9
11.0 - 13.0
4.40
0.0100 - 0.0700
0.0300
0.0100 - 0.0600
3.10 - 28.2
3.10 - 24.0
3.40 - 4.30
2.50-22
5.10
0.0100 - 0.0500
2.90 - 18.7
8.00
4.0
4.10 - 12.4
1JO
0.0100 - 0.0700
0.0100
0.0100
5.60 - 255
0.0100 - 0.0500
0.0100 - 0.0600
2.50 - 503
0.170 - 0.700
179 - 66,700
3.80 - 33.0
4.00 - 31.5
3.70 - 4.30
0.0800 - 1.75
2,160 - 17,800
4,910 - 439,000
0.700 - 20
0.800 - 67.7
34.0 - 39,600
0.800 - 9.0
862-60,000
18.0 - 2,470
4.00 - 62.7
36.5-447
37.7-2^20
759 - 25,900
15 J - 22.0
2,250 - 132,000
5,950 - 44,000
1.30 - 11.7
10.7 - 176
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
100
100
1.0
100
1,000,000
1,000,000
100
100
10,000
100
1,000,000
100
100
10,000
NA
10,000
100
1,000,000
1,000,000
1.0
100
16
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TABLE 2 (Cont'd)
SUMMARY OF CHEMICALS DETECTED IN SHALLOW
GROUND WATER AT MICHAELSVILLE LANDFILL (a)
(a) Samples: MW01-MW07, MW16, WES-M-01, WES-M-02, WES-M-03, WES-M-05, WES-M-06, WES-M-08, WES-M-09,
WES-M-10, WES-M-11, WES-M-13, WES-M-14, WES-M-15, WES-M-17, WES-M-18, WES-M-19, WES-M-21,
WES-M-22, WES-M-23, WES-M-24, and WES-M-25.
(b) USATHAMA chemical codes listed in parentheses.
(c) The number of samples in which a chemical was detected divided by the total number of samples analyzed
for that chemical.
(d) Values reported are total concentrations, except for metals, for which dissolved concentrations are given.
(e) Background concentrations from Walton (1985). Values reported are dissolved concentrations.
(0 Well WES-M-15 was analyzed for explosives on June 2, 1988.
(g) Aroclor-1254 (PCB254).
= Selected as a chemical of potential concern. See text.
ND = Not available.
SOURCE: ICF, PRELIMINARY RISK ASSESSMENT, 1991.
17
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TABLE 3
SUMMARY OF CHEMICALS DETECTED IN DEEP
GROUND WATER AT MICHAELSVILLE LANDFILL (a)
(Concentrations reported in ug/L)
Chemical (b)
Frequency of
Detection (c)
Range of Detected
Concentrations (d)
Background
Concentrations (e)
Organic Chemicals:
Acetone (ACET)
dclta-BHC (DBHC)
* Butylbenzylphthalate (BBZP)
' DDT [TotalJ
4,4'-DDT (PPDDT)
4,4'-DDT (PPDDT)
Dibutylphthalate (DNPH)
* Dieldrin (DLDRN)
* Diethylphthalate (DEP)
Di-n-octylphthalate (DNOP)
Endosulfan I (AENSLF)
bis(2-Ethylhexyi)phthalate (B2EHP)
Heptachlor (HPCL)
Heptachlor Eporide (HPCLE)
Methyfene Chloride (CH2CL2)
* 4-Methylphenol (4MP)
PCBs (0
Phenol (PHENOL)
Inorgank Chemicals:
2/5
1/5
5/5
3/5
1/5
3/5
5/5
2/5
3/5
5/5
2/5
5/5
4/5
2/5
4/5
2/5
2/5
1/5
463 - 2,310
0.0100
4.70 - 8.50
0.0500 - 0.0700
0.0200
0.0500 - 0.0700
5.80 - 19.4
0.0100
3.80 - 10.7
4.50 - 8.20
0.0100
18.7 - 70.8
0.0100 - 0.0400
0.0200
3.50 - 28.3
1.60 - 4.90
0.170 - 0.270
12.7
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Ammonia Nitrogen (NH3N2)
Antimony (SB)
Arsenic (AS)
Beryllium (BE)
Cadmium (CD)
Chloride (CL)
Chromium (CR)
Copper (CU)
Iron (FE)
Lead (PB)
Nickel (NI)
Nitrate (NO3)
Orthophosphate (PO4ORT)
Slenium (SE)
Sulfate (SO4)
Zinc(ZN)
5/5
5/5
3/5
1/5
5/5
5/5
3/5
5/5
5/5
5/5
5/5
5/5
5/5
5/5
5/5
4/5
2,040 . 3,830
14 S - 20.5
5.30 - 11.3
3.30
0.200 - 0.600
2470 - 4,400
0.670 - 10.0
25J-62J
162 - 11,700
1.00 - 9.20
5.70 - 18.7
115-399
1,740 - 2,730
17J - 20.0
7,670 - 11,200
11.0 - 40.0
NA
100
100
1.0
100
1,000,000
100
100
10,000
100
100
10,000
NA
100
1,000,000
100
(a) Samples WES-M-04, WES-M-07, WES-M-12, WES-M-16, and WES-M-20.
(b) USATHAMA chemical codes listed in parenthese*.
(c) The number of sample* in which a chemical was detected divided by the total number of
samples analyzed for that chemical.
(d) Values reported are total concentrations, except for metals, for which dissolved concentrations are given.
(e) Background concenterations from Walton (1985). Value* reported are dissolved concentration*.
(0 Aroclor-1254 (PCB254).
* * Selected as a chemical of potential concern. See text
ND = Not available..
SOURCE ICF, PRELIMINARY RISK ASSESSMENT, 1991.
18
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With respect to spatial distribution of ground water contamination,
in general, the highest constituent concentrations in ground water are
south and east of HLF (IGF, 1991). Potential routes of exposure to humans
include ingestion of and dermal contact with contaminated ground water.
Potential routes of environmental contamination include discharge of
contaminated ground water to surface water bodies. As is discussed in the
following section, the likelihood of a current use of the ground water
below HLF for human consumption is low, and therefore exposure by dermal
contact and ingestion is unlikely. However, a future potential use of
ground water as a drinking water source can not be precluded and exposure
by dermal contact, ingestion or inhalation could still be possible.
KLF Seeps
Multiple erosional rills and gullies cut the southern edge of the
landfill and several seeps are located around the perimeter of the
landfill. Flow from the seeps is intermittent, depending on rainfall.
Seeps in the southern portion of the landfill drain into a nearby drainage
ditch (discussed below). Ten samples were collected by WES from seeps:
May 1988one sample, September 1988one sample, April 1989four samples,
and October 1989four samples (WES, 1990). Seep samples were analyzed for
volatile organic compounds, semivolatile organic compounds, pesticides,
PCBa, and inorganic chemicals.
The chemicals detected in seeps from MLF are shown in Table 4. A
relatively large number of organic chemicals were detected in seep water,
although generally infrequently. These chemicals include volatiles such as
acetone, methylene chloride, and vinyl chloride, as well as phthalates,
pesticides, and PCSa. Blank data available for the October 1989 sampling
round included detections of methylene chloride, butyl benzylphthalate, di-
n-octyl phthalate, bis(2-ethylhexyl)phthalate, and PCBs. Although several
inorganic,chemicals were identified as being potentially elevated above
background levels, no appropriate background data were available with which
to compare site seep levels (ICF, 1991). In lieu of more appropriate data
to characterize levels of inorganics seeping out of natural soils in the
area, ICF used national ground water data. This, however, introduces
considerable uncertainty into this determination. In addition, background
ground water concentrations are dissolved concentrations, whereas seep
concentrations are total concentrations.
Potential routes of human exposure from seeps include ingestion of or
dermal contact with seeps, or ingestion of wildlife that has ingested seep
material. Potential routes of environmental exposure include movement of
seeps to surface water bodies, infiltration of seep material to ground
water, and volatilization of seep components to the air. Because MLF is
19
-------
TABLE 4
SUMMA 17 OF CHEMICALS DETECTED IN
SEEPS A'' MICHAELSV1LLE LANDFILL (a)
(Concentrations reported in ug/L)
Chemical (b)
Organic Chemicals:
Acetone (ACET)
Aldrin (ALDRN)
* Butylbenzylphthalate (BBZP)
4-Oiloroaniline (4CANIL)
DDT [Total]
4,4'-DDD (PPDDD)
4,4'-DDE (PPDDE)
Dibutylphthalate (DNPH)
* cis-l,2-Dichloroethene (C12DCE)
Dieldrin (DLDRN)
Diethylphthalate (DEP)
Di-n-octylphthalate (DNOP)
1,2-Diphenylhydrazine (12DPH)
Ethyl Benzene (ETC6H5)
bis(2-Ethylhexyl)phthalate (B2EHP)
3-Methyi-4-chlorophenol (4CL3C)
Methylene Chloride (CH2CL2)
4-Methylphenol (4MP)
Methoxychlor (MEXCLR)
PAHs [noncarciaogenic] [Total]
Naphthalene (NAP)
PCBs(0
Phenol (PHENOL)
Tetrachloroethene (TCLEE)
Toluene (MEC6H5)
Vinyl Chloride (C2H3CL)
Xylenes [Total] CTXYLEN)
Inorganic Chemicals
Ammonia Nitrogen (NH3N2)
Antimony (SB)
Arsenic (AS)
Cadmium (CD)
Calcium (CA)
Chloride (CL)
Chromium (CR)
Copper (CU)
Iron (FE)
Lead (PB)
Magnesium (MG)
Manganese (MN)
Nickel (NI)
Nitrate (NO3)
Orthophocpoate (PO4ORT)
Potassium (K)
Sodium (NA)
Sulfate (SO4)
Thallium (TL)
Zinc(ZN)
Frequency of
Detection (c)
1/9
1/10
2/7
1/8
2/10
2/10
1/10
4/10
1/9
2/10
2/10
3/7
1/10
2/10
5/6
1/10
4/6
3/8
1/8
1/10
1/10
3/10
1/10
1/10
1/10
1/10
2/9
9/10
3/10
1/10
7/10
1/1
9/9
7/10
9/10
2/2
7/10
1/1
1/1
7/10
10/10
10/10
1/1
1/1
8/9
4/10
8/10
Range of Detected
Concentrations (d)
13.0
0.0300
8.50 - 10.0
1.50
0.0500 - 0.0900
0.0500
0.0400
29.2 - 56.8
620
0.0200 - 0.0400
1.80 - 4.50
4.40 - 9.80
7.40
9 JO - 21.0
2^0-28.9
6.00
7.70 - 9.60
44 A 147
0.0400
2.60
160
0.200-0.500
11.1
5.80
108
53.0
48.0-72.0
150 - 14,900
130 - 210
2.00
0300-570
67300
10,600 - 50,600
3.00 - 57.0
4.00 - 64.0
130,000 - 198,000
1.00 - 164
19,700
1,900
22.0-195
14.0 - 389
33.0 - 1300
10,200
12^00
6,100 - 63,100
4.00 - 27.0
45.0 - 1,180
Background
Concentrations (e)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
100
100
100
1,000,000
1,000,000
100
100
10,000
100
1,000,000
100
100
10,000
NA
10,000
1,000,000
1,000,000
1.0
100
(a) Samples: ArXi-61, SS&-V, ittf-1 - ittf-4, and bttr-A - Sttf-U.
(b) USATHAMA chemical codes listed in
parentheses.
(c) The number of samples in which a chemical wax detected divided by the total number of
samples analyzed. for that chemical
(d) Total concentrations reported.
(e) Background concentrations from Walton (1985). Values reported are
(0 Aroclor-1221 (PCB221).
dissolved concentrations;
* = Selected as a chemical of potential concern. See text
NA = Not available.
SOURCE: ICF, PRELIMINARY RISK ASSESSMENT, 199L
20
-------
located in a secure military installation with limited access, ingestion of
or dermal contact with seeps is unlikely. Furthermore, because hunting ia
not allowed in the vicinity of the site, the likelihood of ingesting
wildlife which has ingested seep material is minimal.
MLF Surface Water
A drainage ditch, which receives runoff from the DRMO scrap metal yard
area, flows into the northeastern edge of the landfill property and then
south adjacent to the landfill (Figure 3). Two low-lying areas and a pond
are located adjacent to the southwestern portion of the landfill. One
surface water sample was collected by WES from each of the following
locations: upgradient approximately 500 feet east of the site in the
drainage ditch that flows south of the landfill, downgradient near the
southwestern corner of the landfill in the same drainage ditch, and the
small pond near the southwestern corner of the landfill (WES, 1990).
Surface water samples were analyzed for volatile organic compounds,
semivolatile organic compounds, pesticides, PCBs, and inorganic chemicals.
No associated blank samples were collected.
The chemicals detected in surface water are shown in Table 5. Low
levels of pesticides (all benzene hexachloride (BHC) isomers) as well as
bis(2-ethylhexyl) phthalate (a common laboratory contaminant) were detected
in site samples. None of these chemicals were detected in the upgradient
sample (although the detection limits were probably very close to the
detected values on-site), except beta-BHC, which was detected at a higher,
but still low, concentration in the upgradient sample than in the site
sample. All organic chemicals detected in surface water were selected as
chemicals of potential concern, although, based on the above discussion,
there is some question as to their association with landfill activities.
A comparison of downstream surface water concentrations of inorganics with
those detected in the upstream sample showed that iron, lead, and nitrate
exceeded upstream concentrations by a factor of two (ICF, 1991).
Potential routes of human exposure from surface water includes
ingestion of or dermal contact with contaminated surface water or ingestion
of wildlife which has ingested contaminated surface water. Because MLF is
located in a secure military installation with limited access, ingestion of
or dermal contact with contaminated surface water is unlikely.
Furthermore, because hunting is not allowed in the vicinity of the site,
the likelihood of ingesting wildlife which has ingested contaminated
surface water is minimal.
21
-------
TABLES
SUMMARY OF CHEMICALS DETECTED IN
SURFACE WATER AT MICHAELSVILLE LANDFILL
(Concentrations reported in ug/L)
Chemical (s)
Frequency of
Detection (b)
Range of Detected Concentrations (c)
On-Site (d)
Background (e)
Organic Chemicals
alpha-BHC (ABHQ 1 / 2
beta-BHC (BBHQ 1 / 2
delta-BHC (DBHC) 1 / 2
gamma-BHC (LIN) 1/2
bis(2-Ethylhexyl)phthalate (BZEHP) 1 / 2
0.0100
0.0100
0.0300
0.0100
33.0
ND
0.410
ND
ND
ND
Inorganic Chemicals:
Ammonia Nitrogen (NH3N2)
Antimony (SB)
Arsenic (AS)
Calcium (CA)
Chromium (CR)
Iron (FE)
Lead (PB)
Magnesium (MG)
Manganese (MN)
Nickel (NI)
Nitrate (NO3)
Orthophosphate (PO4ORT)
Potassium (K)
Selenium (SE)
Silver (AG)
Sodium (NA)
(a) USATHAMA chemicals codes listed
2/2
1/2
2/2
2/2
2/2
2/2
2/2
2/2
2/2
2/2
2/2
2/2
2/2
2/2
1/2
2/2
in parentheses.
(b) The number of samples in which a chemical was detected
284.391
1.00
2.00 . 3.00
8,920 - 8,960
5.00
1,330 - 3,220
2.00 - 3.00
3^50 - 3,630
259-389
6.00 - 9.00
76.0 - 103
22.0 - 292
1,910 - 8,000
19.0 - 28.0
21.0
7,420 - 7,470
divided by the total number
296
ND
2.00
9,050
3.00
735
1.00
3310
723
7.00
34.0
508
2,070
ND
ND
7,480
of samples analyzed for that chemical.
(c) Total concentrations reported.
(d) Samples: APG-DS and APG-POND
(e) Sample: APG-UP.
ND = Not detected
SOURCE ICF, PRELIMINARY RISK ASSESSMENT, 1991.
22
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Air
A total of 12 gaa monitoring wells (G-l through G-12) were installed
in and around the landfill perimeter by WES in January 1989 (WES, 1990).
The locations of these gas monitoring wells are illustrated in Figure 4.
Samples were collected from these wells in February, March, and April 1989.
The analytical results for these three rounds of sampling are provided in
Tables 6, 7, and 8, respectively. The highest methane concentrations have
been detected in wells north and northwest of the landfill (WES, 1990).
In addition to the sampling and analysis of the gas monitoring wells,
the headspace of each ground water monitoring well was monitored for
methane and volatile organic gases prior to sampling during the HGA (WES,
1990). The highest volatile organic headspace reading was 2 parts per
million (ppm) and the highest methane headspace reading was 45 percent.
Methane levels of 90 to 5,971 ppm were also found in the headspace of five
deep monitoring wells sampled by WES in 1988 (WES, 1990).
Ambient air monitoring surveys were also conducted in the area of HLF
by WES in April 1989, using an organic vapor analyzer (OVA), and in March
1990 using an HNU photoionization detector. WES (1990) reported that "no
gases" were detected in either survey. ICF (1991) noted that this kind of
air data is only useful for a qualitative assessment.
Potential routes of exposure to air contaminants include direct
inhalation of contaminants, migration of landfill gases to buildings and
subsequent inhalation of materials or explosion due to gas concentrations,
and dispersion of airborne dusts with subsequent deposition of contaminants
on the ground surface.
VI. SUMMARY OF SITE RISKS
In January 1991, a Preliminary Risk Assessment (PRA) report was
drafted for the MLF site (ICF, 1991). The PRA addressed potential impacts
on human health and the environment associated with the landfill in the
absence of remediation. The PRA was based on data previously collected at
MLF site. Currently, a comprehensive work plan is being developed for the
completion of a Baseline Risk Assessment for the MLF site. The results of
the Baseline Risk Assessment will be evaluated in a subsequent operable
unit decision document. The conclusions of the PRA relevant to the MLF
Operable Unit One are as follows:
The only potentially complete human exposure pathway under current
land use conditions at MLF is the consumption of wildlife that has
accumulated chemicals from the study area. Chlorinated pesticides
23
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TABLE 6
MICHAELSVILLE LANDFILL GAS MONITORING
WELL SAMPLING RESULTS
FEBRUARY 1989
Gas
Well
Gl
G2
G3
G4
G5
G6
G7
G8
G9
G10
Gil
G12*
LEL
Pentane (%)
1
100
100
0
0
0
0
0
100
100
100
100
CO, (%)
0.5
>6.0
>6.0
0.5
0.04
5.2
0.08
0.14
>6.0
42
>6.0
5.0
O. (%)
19.5
3.0
3.0
19.9
20.4
17.0
20.4
20.4
12.0
17.0
18.0
15.0
Total Hydrocarbons
Dom (as Methane)
200
--
--
0
1.2
0
1.2
0
--
--
-
__
'Total hydrocarbon reading upwind 5 feet from the well was 0 to 10 ppm.
SOURCE: WES, 1990.
24
-------
TABLET
MICHAELSVILLE LANDFILL GAS MONITORING
WELL SAMPLING RESULTS
MARCH 1989
Gas
Well
Gl
G2
G3
G4
G5
G6
G7
G8
G9
G10
Gil
G12
Methane(%)
0.00340
3.5
40.0
0.0002
ND
0.0026
0.0004
0.0047
5.1
0.28
0.0950
0.18
Total
Hydrocarbons (%)
0.00340
3.5
40.0
0.0002
ND
0.0028
0.0005
0.0047
5.1
0.29
0.0950
0.19
Oxveen (%)
20.6
17.0
8.2
21.0
21.0
21.0
20.9
20.9
193
20.8
20.9
20.9
Nitrogen (%)
78.9
77.1
31.3
78.9
78.9
78.9
78.9
78.9
72.5
78.3
78.7
78.6
Carbon
Dioxidef%)
0.5
2.3
20.5
0.0760
0.0380
0.0550
0.0900
0.0410
3.1
0.46
0.23
0.17
ND = None Detected.
SOURCE: WES, 1990.
25
-------
TABLES
MICHAELSVILLE LANDFILL GAS MONITORING
WELL SAMPLING RESULTS
APRIL 1989
Gas
Well
Gl
02
G3
G4
G5
G6
G7
G8
G9
G10
Gil
G12
Methane(%)
0.0006
0.020
51.8
0.0026
ND
ND
ND
'0.0008
1.8
23.7
41.0
0.040
Total
Hydrocarbons (%)
0.0010
0.0200
51.80
0.0026
ND
ND
ND
0.0008
1.80
23.70
41.00
0.0140
Oxygen (%)
20.9
13.1
4.7
21.0
21.0
21.0
20.9
21.0
20.0
11.8
7.6
20.9
Nitrogen (%)
79.0
78.7
16.9
78.9
78.9
78.0
79.0
79.0
753
46.2
29.7
78.9
Carbon
Dioxide(%>
0.13
8.20
26.60
0.05
0.07
0.04
0.05
0.04
2.90
1830
21.70
0.06
ND = None Detected.
SOURCE: WES, 1990.
26
-------
and PCBs in surface water, soil and seeps at or near the landfill
have the greatest tendency to bioaccumulate in organisms. The PRA
noted that the potential for significant exposure from ingestion of
game is low to moderate because the wildlife are expected to spend
only a small portion of their total foraging time at MLF, seeps are
intermittent, and ditches are unlikely to be significant sources of
water for large game animals.
Under future land use conditions, the ingestion, dermal contact and
inhalation of ground water is a potential human exposure pathway that
presents potential risks. Additionally, the evaluation of risks
associated with the ingestion of ground water considered future
pumping of off-site wells at a high rate because it could potentially
result in withdrawal of ground water beneath MLF, although this
scenario La highly unlikely. In the PRA, a set of chemicals of
potential concern were selected for detailed evaluation based on the
hydrogeologic assessment sampling results. The principal chemicals
of concern found in the ground water were benzene, 1,1-
dichloroethene, 1,2-dichloroethane, PCB-1254, antimony, beryllium,
cadmium, lead, mercury, nickel, selenium, thallium, chloride, iron,
manganese, and total dissolved solids. The PRA then evaluated the
potential human health risks associated with exposure to these
chemicals of concern.
Excess lifetime cancer risks are determined by multiplying the
intake level with the cancer potency factor. These risks are
probabilities that are generally expressed in scientific notation
(e.g., 1x10"* or 1E-6). An excess lifetime cancer risk of IxlO"6
indicates that, as a plausible upper bound, an individual has a one
in one million chance of developing cancer as a result of site-
related exposure to a carcinogen over a 70-year lifetime under the
specific exposure conditions at a site.
Potential concern for noncarcinogenic effects of a single
contaminant in a single medium is expressed as the hazard quotient
(HQ) (or the ratio of the estimated intake derived from the
contaminant concentration in a given medium to the contaminant's
reference dose). By adding the HQs for all contaminants within a
medium or across all media to which a given population may reasonably
be exposed, the Hazard Index (HI) can be generated. The HI provides
a useful reference point for gauging the potential significance of
multiple contaminant exposures within a single medium or across
.media. If the hazard index exceeds one (1.0), there may be concern
for potential noncarcinogenic effects. As a rule, the greater the
27
-------
value of the hazard index above 1.0, the greater the level of
concern.
In calculating the risks at the site, the exposures evaluated
assume much more extensive contact with the site contaminants than is
currently occurring, or is likely to occur in the future, and as such
are very conservative.
The risks from MLF come from the unlikely but potential
exposure to contaminated ground water and may be summarized as
follows:
- Based on a review of chemical concentrations measured in
ground water monitoring wells on-site, Federal drinking
water standards were exceeded for the following chemicals
(maximum detected concentrations are in parentheses):
benzene (.0175 mg/L), 1,1-dichloroethene (.0216 mg/L),
1,2-dichloroethane (.0092 mg/L), PCB-1254 (.0008 mg/L),
antimony (.052 mg/L), beryllium (.008 mg/L), cadmium (.01
mg/L), lead (.024 mg/L), mercury (.007 mg/L), nickel
(.140 mg/L), selenium (.061 mg/L), thallium {.Oil mg/L),
chloride (619 mg/L), iron (54.3 mg/L), manganese (24.6
mg/L), and total dissolved solids (1096 mg/L).
- The upperbound excess lifetime cancer risk for ingestion
of shallow ground water is 2E-04, which is in excess of
1E-06, due primarily to beryllium. Table 9 presents the
contaminants of concern, the cancer risks, and the hazard
quotients (CDI:RfO ratio) reported in the PRA.
- The hazard index for shallow ground water is 4.0. The
hazard index for deep ground water is 1.0.
- The risks presented for exposure to ground water provide
an upper bound indication of potential future risks under
the unlikely scenario in which future land use requires
the high-rate pumping of off-site wells, and in which no
further ground water remediation is considered. Capping
the landfill will significantly reduce the further
migration of contaminants from the landfill, and the
Army's ground water remedial investigation will address
additional ground water remediation needs.
Some chlorinated pesticides present in surface water pose an
increased risk of adverse acute and chronic effects in more sensitive
aquatic invertebrates and insects at MLF. Furthermore, selenium,
28
-------
TABLE 9
POTENTIAL RISK ASSOCIATED WITH HYPOTHETICAL FUTURE INGESTION OF
SHALLOW GROUND WATER AT MICHAELSVILLE LANDFILL (a)
Chemicals Exhibiting
Carcinogenic Effect* (b)
Aldrin (ALDRIN)
Benzene (C6H6)
alpha-BNC (ABHC)
beta-BHC (BBHC)
Chloroform (CHCL3)
4,4'-DDD (PPDDD)
4,4'-DDT (PPDDT)
1,2-Dichloroethane (12DCLE)
Dieldrin (DLDRN)
1,2-Diphenylhydrazine (12DPH)
bis(2-Ethythexyt)phthlate(B2EHP)
Heptachlor (HPCL)
Heptachlor Epoxide (HPCLE)
Methylene Chloride (CH2CU)
PCBs
Estimated Chrnnk
Daily Intake (CDI)
(mg/kg-day)
UE-07
3.2E-05
1.2E-07
1.2E-07
3.3E-05
1.2E-07
3.7E-07
3.3E-05
1.2E-07
1.6E-05
1.6E-03
2.4E-07
1.2E-07
3.3E-04
2.7E-06
Slope
Factor
(mg/kg-day)-l
1.7E+01
2.9E-02
6.3E + 00
1.8E + 00
6.1E-03
2.4E-01
3.4E-01
9.1E-02
1.6E+01
8.0E-01
1.4E-02
4.5E + 00
9.1E+00
7.3E-03
7.7E + 00
Weight of
Evidence
Class (c)
B2
A
B2
C
B2
B2
B2
B2
B2
B2
B2
B2
B2
B2
B2
Upper Bound
Excess Lifetime
Cancer Risk
2E-06
9E-07
8E-07
2E-07
2E-07
3E-08
1E-07
3E-06
2E-06
IE-OS
2E-05
1E-06
1E-06
2E-06
2E-05
Beryllium (BE)
TOTAL
Chemicals Exhibiting
Noncareinogenic Effects (b)
3.4E-05
Estimated Chronic Reference Dose
Daily Intake (CDI) (RfD)
(mg/kg-day) (mg/kg-day)
4.3E + 00
Uncertainty
Factor
B2
Target
Organ (e)
1E-04
2E-04
CDI:Rfl>
Ratio
Acetone (ACET)
Aldrin (ALDRIN)
Butylbenzylphthalate (BBZP)
Chloroform (CHCL3)
4,4'-DDT (PPDDT)
Dibutylphthlate (DNPH)
1,1-Dichloroethane (11DCLE)
cia-l,2-Dichloroethene(C12DCE)
trans-l,2-Dichloroethene(T12DC)
Dieldrin (DLDRN)
Diethylphthlate (DEP)
2,4-Dimethylphenol (24DMPN)
1 J-Dinitrobenzene (13DNB)
Di-n-octylphthalate (DNCP)
Endosulfane (AENSLF & BENSLF)
bis (2-ethyihexyl)phthlate (B2EHP)
Heptachlor (HPCL)
Heptachlor Epoxide (HPCLE)
Methylene Chloride (CN2CL2)
PCBs
Ammonia (NH3)
Beryllium (BE)
Manganese (MN)
Thallium (TL)
Zinc(ZN)
HAZARD INDEX
1.5E-03
2.9E-07
1.9E-04
7.7E-OS
8.6E-07
3.7E-04
l.OE-04
1.2E-04
7.7E-05
2.9E-07
2.1E-04
1.5E-04
1.1E-04
1.7E-04
1.7E-07
3.7E-03
5.7E-07
2.9E-07
7.7E-04
6JE-06
2.0E-01 (Q
8.0E-05
7.1E-02
8.3E-05
1.7E-03
l.OE-01
3.0E-05
2.0E-01
l.OE-02
5.0E-O4
l.OE-01
l.OE-01
l.OE-02
2.0E-02
5.0E-05
8.0E-01
2.0E-02
l.OE-04
2.0E-02
5.0B-05
2.0E-02
5.0E-04
UE-05
6.0E-02
l.OE-04
9.71E-01
5.0E-03
7.0&OS
2.0E-01
(g)
1,000
1,000
1,000
1,000
100
1,000
1,000
3,000
1,000
100
1,000
3,000
3,000
1,000
3,000
1,000
300
1,000
100
100
_
100
1
3,000
10
Kidney/Liver
Liver
Testes/Ltver/Kidney
Liver
Liver
Mortality
Kidney
Blood
Blood
Liver
Body Weight
Blood
Spleen
Liver/Kidney
Kidney
Liver
Liver
Liver
Liver
Fetus
_
Various Organs (Tumors)
CNS
Blood/Hair
Blood (Anemia)
1E-02
1E-02
1E-03
8E-03
2E-03
4E-03
1E-03
1E-02
4E-03
6E-03
3E-04
8E-03
1E + 00
8E-03
1E-02
2E-01
1E-03
2E-02
1E-02
6E-02
2E-01
2E-02
7E-01
1E-KX)
8E-03
-------
TABLE 9 (Cont'd)
POTENTIAL RISK ASSOCIATED WITH HYPOTHETICAL FUTURE INGESTION OF
SHALLOW GROUND WATER AT MICHAELSVILLE LANDFILL (a)
(a) Risks arc calculated only for chemicals with toxicity criteria. The following chemicals of potential concern are
not presented due to lack of toxicity criteria: delta-BHC chloroethane, endosulfan sulfate, and iron.
(b) USATHAMA chemical codes listed in parentheses.
(c) EPA Weight of Evidence for Carcinogenic Effects:
(A) - Human carcinogen based on adequate evidence from human studies;
[B2] = Probable human carcinogen based on inadequate evidence from human studies and adequate evidence from animal studies; and
[C] = Possible human carcinogen based on limited evidence from animal studies in the absence of human studies.
(d) Factor which reflects the uncertainty in the estimate of the RfD. Larger factors are associated with greater uncertainty.
(e) A target organ is the organ most sensitive to a chemical's toxic effect. RfDs are based on toxic effects in the target organ. If an
RfD was based on a study in which a target organ was not identified, an organ or organ system known to be affected by the chemical is listed.
(0 The estimated GDI is based on the concentration of ammonia nitrogen.
(g) The RfD for ammonia, based on a taste threshold, was converted from mg/L to mg/kg-day by assuming that a 70 kg adult
drinks 2 liters of water per day.
SOURCE: ICF, PRELIMINARY RISK ASSESSMENT, 1991.
30
-------
which has been found in ground water, could bioaccumulate through the
food chain and adversely affect terrestrial wildlife such as
sandpipers and raccoons. However, the PRA noted that because these
species are not expected to spend large amounts of time in surface
water bodies in the MLF area (such as on-site ditches), the overall
impact on the wildlife population is likely to be minimal. The
Baseline Risk Assessment will quantify these impacts.
The risks summarized above are addressed by the remediation goals for
MLF because the remediation goals serve to prevent contact with waste,
while minimizing the migration of liquids through the landfill. Actual or
threatened releases of hazardous substances from MLF, 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.
VII. DESCRIPTION OF ALTERNATIVES
The general remedial action objectives for MLF are to: provide long-
term minimization of migration of liquids through the landfill; ensure that
the "cover will function with minimal maintenance; promote drainage and
minimize erosion or abrasion of the cover; accommodate settling and
subsidence so that the cover's integrity is maintained; and provide
adequate venting for any methane gases produced by the landfill wastes.
A number of remedial alternatives were developed to significantly
reduce the risk to public health and the environment from exposure to
and/or transport of contaminants that may be associated with surface water
runoff or surface water infiltration and subsequent leachate generation at
MLF. The Superfund law requires that each remedy selected to address
contamination at a hazardous waste site be protective of human health and
the environment, be cost effective, and be in accordance with statutory
requirements.
The capping alternatives evaluated for MLF are summarized in Table 10.
The excavation alternatives are summarized in Table 11. The costs for
implementing each alternative include preliminary estimates of capital
outlay and estimates for operation and maintenance (O&M), as well as
present worth costs.
VIII. SUMMARY OP COMPARATIVE ANALYSIS OF ALTERNATIVES
The eight remedial action alternatives developed for MLF, as described
in Tables 10 and 11, were evaluated by the Army using aine specific
31
-------
TABLE 10
SUMMARY OF CAPPING ALTERNATIVES
Cost
Present
Alternative Capital O&M/year Worth a
1. No Action SO $0 $0
The Superfund program requires that the "no action"
alternative be evaluated at every site to establish a
baseline for comparison of other alternatives. This
alternative consists of no additional remedial action at
MLF. This alternative could be implemented
immediately.
2. Redressing the Landfill Cap $7,027,300 $27,000 $7,442,400
This alternative consists of redressing the existing cap
with a minimum 3-foot-thick, low permeability
compacted clay, graded to provide adequate surface
drainage and stabilized with topsoil and grass. A gas
venting system would also be incorporated into the
cap design to minimize the migration or accumulation
of gases generated by the landfill wastes. This
alternative could be implemented within 6 to 8
months.
3. Installing a New Cap in Accordance With MDE $9,201,500 $27,000 $9,616,600
Requirements for Sanitary Landfill Closure Using
Off-Post Clay
This alternative consists of installing a new, multi-
layered cap in accordance with MDE requirements,
using clay from an off-post borrow source (Code of
Maryland Regulations (COMAR 26.04.07.21). The
design features of this system include a minimum 2
feet of compacted earthen material over the existing
landfill cover; 1 foot of clay material (in-place
permeability less than or equal to IxlO'5 centimeters
per second (cm/sec)) over the earthen material; 6
inches of sand drainage material (in-place
permeability greater than 1x10° cm/sec) over the
clay; and a final earthen cover (minimum 2 feet thick)
with a 4 percent minimum slope and vegetative
stabilization. A gas venting system would also be
incorporated into this cap design to minimize the
migration or accumulation of gases generated by the
landfill wastes. This alternative could be
implemented within 10 to 14 months.
32
-------
TABLE 10 (Cont'd)
SUMMARY OF CAPPING ALTERNATIVES
Alternative
Installing a New Cap in Accordance With Resource
Conservation and Recovery Act (RCRA)
Requirements for Hazardous Waste Landfill
Closure
This alternative consists of installing a new, multi-
layered cap in accordance with RCRA requirements,
using both off-post clay and a synthetic geomembrane
to limit surface water infiltration into the landfill (40
Code of Federal Regulations 264.310). The design
features of this system include low permeability
(IxlO"7 cm/sec or less) clay over the existing MLF
cover; a synthetic geomembrane over the clay
(minimum thickness 20 mil); a 1-foot-thick sand
drainage layer (minimum permeability IxlO'3 cm/sec
or more); and a final earthen cover (minimum 2 feet
thick) with a 4 percent slope and vegetative
stabilization. A gas venting system would also be
incorporated into the cap design to minimize the
migration or accumulation of gases generated by the
landfill wastes. This alternative could be
implemented within 10 to 14 months.
Capital
$9,585,900
Cost
O&M/year
Present
Worth a
$27,000 $10,001,000
5. Installing a New Cap in Accordance With MDE
Requirements for Sanitary Landfill Closure Using
a Geosynthetic Membrane
This alternative consists of installing a new, multi-
layered cap in accordance with MDE requirements,
using a geosynthetic membrane (COMAR
26.04.07.21). The design features of this system
include a minimum 2 feet of compacted earthen
material over the existing landfill cover; a
geosynthetic membrane (minimum thickness 20 mil)
over the earthen material; 12 inches of sand drainage
material (in-place permeability greater than IxlO"3
cm/sec) over the membrane; and a final earthen cover
(minimum 2 feet thick) with a 4 percent minimum
slope and vegetative stabilization. A gas venting
system would also be incorporated into the cap design
to minimize the migration or accumulation of gases
generated by the landfill wastes. This alternative
could be implemented within 10 to 14 months.
$8,792,100
$27,000
$9,207,200
'Net present worth cost includes 30 years O&M for Alternatives 2, 3, 4, and 5.
SOURCE: Dames & Moore, 1992b.
33
-------
TABLE 11
SUMMARY OF EXCAVATION ALTERNATIVES
Alternative
1A. Excavating and Hauling the Waste Off-site
This alternative involves excavating the waste
material at MLF, loading the waste onto trucks,
hauling it to an off-post hazardous waste landfill,
and refilling the excavation with clean fill. This
alternative could be implemented within 10 to 24
months.
Capital
$135,520,000
Cost
O&M/year
Present
Worth a
$0 $135,520,000
2A. Excavating and Incinerating the Waste
This alternative consists of excavating the waste
material at MLF, transporting it to a mobile, on-
site, rotary-kiln incinerator, and destroying it.
The stabilized, non-hazardous ash is then
returned to the ground as fill. This alternative
could be implemented within 64 to 72 months.
$182,795,000
$0 $182,795,000
3A. Excavating the Waste, Lining the Cavity,
Replacing the Waste, and Capping the
Landfill.
This alternative involves excavating the waste at
MLF, storing the waste in a temporary
impoundment while a liner system is installed in
the excavation cavity, returning the waste to the
lined cavity and capping the landfill. The liner
will consist of a 12-inch thick leachate collection
layer of sand embedded with perforated
collection lines and covered by a synthetic
membrane, a similar 12-inch thick leak detection
layer and a 2-foot thick compacted subbase. The
cap will be configured as described in
Alternative 5 in Table 9. This alternative could
be implemented within 18 to 24 months.
$21,135,000
$690,000
21,825,000
'Net present worth cost includes 30 years O&M for Alternative 3A.
SOURCE: Dames & Moore, 1992b.
34
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evaluation criteria.
These nine criteria are:
Threshold Criteria
1) Overall protection of human health and the environment; and
2) Compliance with applicable or relevant and appropriate
requirements.
Primary Balancing Criteria
3) Long-term effectiveness and permanence;
4) Reduction of toxicity, mobility, or volume through treatment;
5) Short-term effectiveness;
6) Implementability; and
7) Cost.
Modifying Criteria
8) State/support agency acceptance; and
9) Community acceptance.
The following sections present a brief discussion of each of the
evaluation criteria and a comparative analysis of each of the alternatives
based on the nine criteria.
Overall Protection of Human Health and the Environment
The criterion addresses whether or not a remedy will (1) clean up a
site to within the risk range; (2) result in any unacceptable impacts; (3)
control the inherent hazards (e.g., toxicity and mobility) associated with
a site; and (4) minimize the short-term impacts associated with cleaning up
the site.
The primary human health risk associated with the site is from
exposure to and/or transport of contaminants that may be associated with
surface water runoff or surface water infiltration and subsequent leachate
generation at MLF.
The No-Action Alternative (Alternative 1) does not abate the risk of
potential exposure to and/or transport of MLF contaminants. Therefore,
Alternative 1 is not protective of human health and the environment and
will not be discussed further.
Although the three excavation alternatives would all be protective of
human health and the environment after implementation, each one would
create additional exposure pathways during implementation. They cause an
increased potential for human health exposure during the excavation of the
35
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waste, during which time local residents, APG workers, and site workers
face an increased potential for inhalation of and dermal contact with the
concentrated contaminants as they are disturbed, excavated, and perhaps
released to the environment. In addition, the excavation process may
create additional pathways for environmental degradation if materials are
released during transport. Implementation of the excavation alternatives
will create a risk to human health and the environment over a long period
of time. Therefore, the excavation alternatives provide a low overall
protectiveness of human health and the environment. Furthermore, the
excavation alternatives are costly and currently, the contaminants from
this site are not extremely mobile.
With respect to the Alternatives 2, 3, 4, and 5, Alternative 2 was
determined to provide a moderate level of overall protectiveness;
Alternative 3 was determined to provide a moderate to high level of overall
protectiveness; and Alternatives 4 and 5 were determined to provide high
levels of overall protectiveness. Alternative 2 would not provide the
long-term effectiveness offered by Alternatives 3, 4, and 5 because no
drainage layer is included. Alternative 3, in turn, is expected to be less
effective than Alternatives 4 and 5 in the long term, because clay material
is more permeable than geomembrane material and would thereby allow more
infiltration of surface water into the landfill cap. Alternative 4 is
considered to provide a slightly higher degree of overall protection than
Alternative 5 because Alternative 4 provides both a clay layer and a
geomembrane layer to prevent infiltration of surface water.
Compliance With ARARs
This criterion addresses whether or not a remedy will meet all of the
applicable or relevant and appropriate requirements of other environmental
statutes and/or provide grounds for invoking a waiver.
A complete listing of all site-related action and location specific
ARARs is presented in Table 12. Alternative 2 would fail to meet the MOE
sanitary landfill closure requirements. Alternatives 3, 4, 5, 1A, 2A, and
3A would satisfy all ARARs. It should be noted that in August 1991, EPA
and MOE determined that RCRA requirements for hazardous waste landfill
closure would not have to be met by the MLF cap and cover system design
because most of the materials disposed of in the landfill were domestic
trash and other nonhazardous wastes from nonindustrial sources.
The implementation of any of the remedial action alternatives at MLF
will impact 1.5 acres of emergent wetlands, 0.5 acres of wooded wetlands,
and 0.25 acres of ponded area. To comply with the U.S. Army Corps of
Engineers' Nationwide Permit Program authorized under CERCLA, 33 CFR 330,
36
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TABLE 12
REVIEW OF POTENTIAL ACTION-SPECIFIC AND LOCATIONAL ARARs
FOR MICHAELSVILLE LANDFILL REMEDIAL ACTION ALTERNATIVES
Environmental Laws and Regulations
RCRA
A. Subtitle D land disposal criteria
(40 CFR Part 257)
B. Subtitle C requirements
1. Closure and postclosure
(40 CFR Part 264, Subpart G)
2. Ground water monitoring and protection
(40 CFR Part 264, Subpart F)
3. Standards applicable to tanks and containers
(40 CFR Part 264, Subparts I and J)
4. Standards applicable to surface impoundments,
waste piles, land treatment facilities (other than
closure and postclosure requirements)
(40 CFR Part 264, Subparts K, L, and M)
5. Location standards
(40 CFR Part 264, Subpart B)
Consideration as an ARAR
Retained
for ARAR
Analysis?
Two of the excavation alternatives require on-site landfilling of YES
solid waste.
Waste materials will be contained in place under (he capping YES
alternatives, requiring a cover.
Hazardous wastes may exist. These wastes will be capped in YES
place or excavated.
Hazardous wastes will be temporarily stored on-site in YES
containers or tanks under the excavation alternatives.
Surface impoundments, waste piles, and land treatment facilities NO
will not be considered as MLF remedial action alternatives.
Portions of streams downgradient of the site may be located YES
within the 100-year flood plain, though none are located in a
seismic area, as defined by the regulations.
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TABLE 12 (Cont'd)
Environmental Laws and Regulations
Consideration as an ARAR
Retained
for ARAR
Analysis?
Ul
CD
II.
6. Transportation standards
(40 CFR Part 263)
7. Incinerator standards
(40 CFR Part 264, Subpart O)
8. Landfill standards
(40 CFR Part 264, Subpart N)
9. Land disposal restrictions
(40 CFR Part 268)
10. Underground storage tank (UST) regulations
(40 CFR Part 280)
11. Guidelines for the thermal processing of solid
wastes (40 CFR Part 240)
12. Standards applicable to miscellaneous units
(40 CFR 264, Subpart X)
Clean Water Act
A. National Pollution Discharge Elimination System
(NPDES) requirements (40 CFR Parts 122-124)
Shipments of hazardous waste off-post could be necessary under YES
any of MLF remedial action alternatives.
Incineration is considered as an MLF remedial action alternative YES
in conjunction with the excavation of the waste.
Design requirements for a hazardous waste landfill cap will be YES
considered as a remedial action alternative.
Land disposal will be considered under the excavation options. YES
These restrictions may apply if certain hazardous wastes are
excavated and disposed in a landfill. These restrictions also
apply to leachate and other hazardous by-products which may be
produced.
UST rules will not apply to the remediation of this site. NO
Excavation and incineration of wastes is one of the alternatives YES
under consideration.
These standards apply to non-interim hazardous waste NO
management units that are not covered by other permitting
regulations, which are not expected to be used for certain
remedial action alternatives.
Remedial actions will not result in direct discharge to surface NO
water from a discrete source.
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TABLE 12 (Cont'd)
Environmental Laws and Regulations
Consideration as an ARAR
Retained
for ARAR
Analysis?
Ul
vO
B. Ambient water quality criteria (AWQC)
(Federal Register, 1980; 1985)
(40CFRPart 131)
C. Clean Water Act Requirements
(40 CFR Paris 230-233)
D. General pretreatment standards
(40 CFR 403)
111. Safe Drinking Water Act
A. Underground injection control
(40 CFR Parts 144-147)
B. Maximum Contaminant Levels (MCLs)
(40 CFR Parts 141 and 143)
IV. Marine Protection, Research, and-Sanctuaries Act
A. Incineration at sea requirements
(40 CFR Parts 220-228)
Alternatives under consideration will not result in discharges to NO
surface water. Therefore, AWQC should not be relevant and
appropriate to these remedial actions.
Remedial actions will affect wetlands defined under this act. YES
New wetlands will be created to offset disturbed wetlands.
Discharges to publicly-owned treatment works (POTWs) are not NO
envisioned under the remedial alternatives considered for the
site.
No underground injection of wastes is.envisioned for this site. NO
As noted in Section 2.2, the issue of ground water contamination NO
and remediation is outside the scope of this FFS and will be
addressed in Operable Unit Two.
No wastes from the site are expected to be incinerated at sea. NO
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TABLE 12 (Cont'd)
Environmental Laws and Regulations
Consideration as an ARAR
Retained
for ARAR
Analysis?
V.
Toxic Substances Control Act
A. Polychlorinated biphenyls (PCBs) requirements
(40 CFR Part 761)
VI. U.S. Army Corps of Engineers
A. Dredge and fill
(33 CFR Part 323)
B. Construction in waterways
(33 CFR Part 322)
C. Clean Water Act Requirements Section 404
Nationwide Permits
(33 CFR Part 330, Appendix A #38)
VII. Clean Air Act
A. National Ambient Air Quality Standards (NAAQS)
(40 CFR Part 50)
B. National Emission Standard for Hazardous Air
Pollutants (NESHAPS) (40 CFR Part 61, Subpart M)
PCBs have been detected at very low concentrations (less than YES
1 mg/1) in ground water and seep samples (see Section 1.2.3).
Digging into the buried waste material and exposing PCBs at
greater concentrations is proposed under the excavation
alternatives. Therefore, PCB incineration, disposal, and cleanup
requirements apply to the excavation remedial alternatives under
consideration.
Remedial alternatives under consideration are not expected to NO
result in any dredging or filling in a navigable or U.S.
waterway.
No construction in navigable waterways will be required for the NO
remedial actions under consideration.
Nationwide Permit for NPL Site is exempt under CERCLA. In YES
any event, the wetlands impacted by the Selected Remedy will
be replaced.
Remedial alternatives involving earthmoving operations may YES
result in emissions to air.
Remedial alternatives involving earthmoving operations may YES
result in emissions to air.
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TABLE 12 (Cont'd)
Environmental Laws and Regulations
Consideration as an ARAR
Retained
for ARAR
Analysis?
VIII. Occupational Safety and Health Administration
(OSHA) Requirements
A. Requirements for workers at remedial action sites
(29 CFR Part 1910)
IX. U.S. Department of Transportation (DOT)
Regulations (49 CFR Parts 170-179)
X. Response in a Flood Plain or Wetlands
(40 CFR Part 6, Appendix A, and Executive Orders
11988 and 11990)
XI. Conservation of Wildlife Resources (Fish & Wildlife
Coordination Act) (50 CFR Parts 400-499)
XII. Preservation of Rivers on the National Inventory (40
CFR Part 6)
XIII. Preservation of Scientific, Historic, or Archaeological
Data (Archaeology and Historic Preservation Act of
1974)
XIV. State of Maryland
A. Maryland Air Pollution Control Regulations
(COMAR 26.11.01 -.23)
Any remedial action on-site must be performed in accordance YES
with applicable OSHA standards.
Contaminated soil and other waste materials could be transported YES
offpost under any of MLF remedial action alternatives under
consideration.
Portions of APG-AA are considered wetlands. Any remedial YES
actions must consider adverse impacts to these areas. MLF site
is not within the 100-year flood plain.
The bald eagle is an endangered species known to be present at YES
APG.
No wild and scenic rivers are found in the vicinity of the study NO
site.
No designated scientific, historic, or archaeological sites have NO
yet been located in the vicinity of the study site.
Remedial alternatives involving earthmoving operations may YES
result in the discharge of pollutants to the atmosphere.
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TABLE 12 (Cont'd)
Environmental Laws and Regulations
Consideration as an ARAR
Retained
for ARAR
Analysis?
(O
B. Maryland Water Pollution Control Regulations
(COMAR 26.08.01-.04)
C. Maryland Sanitary Landfill Closure Regulations
(COMAR 26.04.07.21)
D. Maryland Erosion and Sediment Control Regulations
(COMAR 26.09.01)
E. Maryland Drinking Water Quality Standards
(COMAR 26.04.01)
Remedial actions will not result in the discharge of pollutants to NO
State waters, which include both surface and ground waters.
This regulation provides design requirements for the closure YES
(capping) of sanitary waste landfills.
Excavation, dredging, and backfilling activities at the site may YES
cause increased erosion and sediment runoff requiring the
application of control measures during remediation.
These regulations establish drinking water quality standards in NO
conjunction with the Federal standards under the Safe Drinking
Water Act. See comments under III.B above.
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Appendix A /38, the Army will replace the impacted wetlands by creating 1.5
acres of emergent wetlands, 1 acre of wooded wetland, and 0.25 acres of
ponded area at the Romney Creek Wetlands Compensation/Mitigation Site. The
Romney Creek Wetland Compensation/Mitigation Site concept plan is currently
being developed with the assistance of the U.S. Army Corps of Engineers,
Baltimore District.
Long-Tern Effectiveness
This criterion refers to the ability of a remedy to maintain reliable
protection of human health and the environment over time, once cleanup
goals have been met.
Alternative 2 would reduce the potential for future migration of
contaminants from MLF by preventing the infiltration of surface water into
the landfill, the discharge of seep water from the landfill, and the
erosion of the landfill cover. However, the lack of a drainage layer in
the conceptual design of this alternative increases the chances for future
migration of contaminants over the long term. Proper construction and
continued maintenance of the cap would be essential to help maintain the
integrity of the cap design under Alternative 2.
Alternatives 3, 4, and 5 would significantly reduce the potential for
future migration of contaminants from MLF by limiting surface water
infiltration, seep discharges/ and landfill cover erosion. These three
alternatives would also provide a drainage layer, which is not included in
Alternative 2. This drainage layer would help promote the drainage of
surface water and limit ponding and infiltration through the landfill cap
material. Although future migration of contaminants could occur with
Alternatives 3, 4, and 5 because the buried waste would be left in place
and the cap integrity could diminish over time, proper construction and
continued maintenance of the cap would serve to maintain the integrity of
the cap under these alternatives.
In comparing Alternatives 3, 4, and 5, Alternative 4 is expected to
provide a slightly higher degree of long-term effectiveness than
Alternatives 3 and 5 because both a geomembrane liner and a clay layer are
included in the conceptual design of Alternative 4. Alternative 3, in
turn, is expected to provide less protection against long-term infiltration
through the cap than Alternative S because the clay material is more
permeable than the synthetic liner.
Alternative 1A (excavating and hauling the waste off-site) provides
the highest level of long-term effectiveness on-site because the source is
removed. However, the source is not destroyed but transferred to another
location, and continues to carry long-term liability. Alternative 2A
43
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(excavating and incinerating the waste) also has a high level of long-term
effectiveness because it involves removing and destroying the source.
However, approximately 25% of the volume of the waste material will remain
as ash and require landfilling at the site. Although the ash can be
stabilized, the stabilization process is not permanent and the ash will
eventually break down and potentially release concentrated contaminants to
the environment. Alternative 3A (excavating the waste, lining the cavity,
replacing the waste, and capping the landfill) has a moderate to high level
of effectiveness because it involves isolating the waste and preventing
infiltration like the other capping alternatives. In addition, this
alternative also provides the added protection of a liner beneath the
waste. However, the waste will still remain in place.
Reduction of Toxicitv, Mobility, and Volume
This criterion refers to the anticipated performance of the treatment
technologies that may be employed in a remedy.
Alternatives 2, 3, 4 and S would serve to reduce the mobility of
contaminants present in MLF by reducing infiltration, leachate generation,
and contaminant migration. Alternative 4 is expected to reduce
infiltration, leachate generation, and contaminant migration more
effectively than the three other containment alternatives because both a
clay layer and a geosynthetic membrane are used. Alternatives 3, 4, and 5
are expected to reduce infiltration, leachate generation, and contaminant
migration more effectively than Alternative 2, in which the lack of a
drainage layer could make the landfill cap more susceptible to these
problems in the long term. Alternative 5 could be slightly more effective
than Alternative 3 in reducing infiltration, leachate generation, and
contaminant migration because the geosynthetic membrane associated with
Alternative 5 is expected to be less permeable than the clay layer
associated with Alternative 3.
Alternative 1A would reduce the volume of the waste by removing the
source to another location. The toxicity and mobility of contaminants
would be minimized at the site because the waste would be removed.
However/ the toxicity of the contaminants transferred to another location
would remain the same even though the mobility would be reduced in a secure
landfill. Alternative 2A would reduce the volume, mobility, and toxicity
of the contaminants by removing the waste from the site and destroying it
by incineration. However, 25% of the waste volume would remain as ash and
the toxicity and mobility of the ash would be reduced only over the short-
term by stabilization. Even after the ash is stabilized and replaced on-
site, the ash will degrade and mobilize contaminants after some period of
time. Alternative 3A will not affect the volume or toxicity of the waste,
44
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although the lined excavation will reduce the mobility.
Short-Term Effectiveness
This criterion refers to 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
cleanup goals have been achieved.
Alternatives 2, 3, 4, and 5 are expected to take about the same amount
of time (10 to 14 months) to implement. The limited potential for exposure
of workers to site contaminants under Alternatives 2, 3, 4, and 5 could be
controlled with proper personal protective equipment, spraying of work
areas with water to minimize dust generation, and appropriate training. A
temporary silt fence would be used during construction to minimize any
transport of contaminants via surface water runoff. Therefore, all four
containment alternatives are expected to provide adequate short-term
effectiveness.
The three excavation alternatives provide a low level of short-term
effectiveness because the waste will be disturbed during excavation.
During excavation, there is a significant potential for worker exposure to
contaminants and hazards, a potential for further environmental exposure to
contaminants during transport, and a potential for significant airborne
dispersion of contaminants. Although health and safety controls can be
used to reduce the potential effects, the risk to human health and the
environment during excavation would be significant.
Implementabilitv
This criterion describes the technical and administrative feasibility
of a remedy, including the availability of materials and services needed to
implement the chosen solution.
Alternatives 2, 3, 4 and S are technically feasible. Alternative 2
would be easiest to implement because the design requirements for the cap
and cover system would be the least complex. Alternatives 3, 4, and 5 are
expected to be somewhat more difficult to implement than Alternative 2
because the design considerations are slightly more complex. There does
not appear to be a significant difference in implementation considerations
among Alternatives 3, 4, and 5.
Alternatives 3, 4, and 5 are expected to be acceptable to regulatory
agencies because all would meet ARARs. Alternative 4 could have a slight
advantage over Alternatives 3 and 5 because, in the future, regulatory
agencies might determine that compliance with RCRA design requirements for
the cap and cover system is necessary. Alternative 2 would be the capping
45
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alternative least acceptable to the regulatory agencies because it would
not meet all ARARs. Thus, Alternatives 3, 4 and 5 all have an advantage
over Alternative 2. Alternative 4 has a slight advantage over Alternatives
3 and 5 in terms of administrative feasibility.
The three excavation alternatives will be difficult to implement.
Alternative 1A is difficult to implement because of the large volume of
waste which must be excavated, hauled off-site, and placed in a secure
landfill. The volume is so large that there is a possibility that existing
landfills would not have the capacity to accept the waste and a new
landfill would have to be constructed to accommodate the waste.
Alternatives 2A and 3A are also difficult to implement, again due to the
large volume of waste. For this volume of waste, the incineration process
proposed in Alternative 2A would require more than 8 years to complete.
Cost
This criterion addresses the capital for materials, equipment, etc.,
and the O&M costs.
Excavation alternative costs are two to twenty times as much as the
capping alternative costs. Assuming a Present Worth Cost which includes 30
years of O&M costs. Alternative 2A is the most expensive excavation
alternative with a Present Worth Cost of $182,795,000. Alternative 1A is
the next most expensive excavation alternative with a Present Worth Cost of
$135,520,000. Alternative 3A is the least costly excavation alternative
with a Present Worth Cost of $21,825,000. Alternative 4 would be the most
expensive capping alternative to implement with a Present Worth Cost of
$10,001,000. Alternative 2 would be the least expensive to implement with
a Present Worth Cost of $7,442,400. However, as discussed above,
Alternative 2 would not meet MOB sanitary landfill closure requirements.
Alternatives 3 and 5 have Present Worth Costs of $9,616,600 and $9,207,200,
respectively. Therefore, Alternative 5 is the most cost-effective remedy
which meets all ARARs.
The Army has selected Alternative 5 for the remediation of MLF.
Alternative 5 offers a cost-effective cap and cover system while providing
adequate protection of human health and the environment.
Support Agency Acceptance
This criterion indicates whether, based on their review of the RI,
FFS, Proposed Plan, and the ROD, the support agencies concur with, oppose,
or have no comment on the Selected Remedy.
.EPA and MDE concur with the Selected Remedy.
46
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Community Acceptance
This criterion assesses the public comments received on the RI, FFS,
and Proposed Plan.
A public meeting was held on April 9, 1992, at the Aberdeen Area
Chapel, APG. This meeting lasted approximately 2 hours, and the members of
the public in attendance were able to have all of their questions about the
site answered. Written comments were received during the public comment
period. The major concerns of the community involved the protection of
ground water. The Responsiveness Summary which is included in this ROD
responds to all written public comments received.
IX. DESCRIPTION OF THE SELECTED REMEDY
Based upon the requirements of CERCLA and the detailed evaluation of
the alternatives, the Army has determined that Alternative 5, Installing a
New Cap in Accordance with MOB Requirements for Sanitary Landfill Closure
Using a Geosynthetic Membrane, is the most appropriate remedial alternative
for MLF Operable Unit One at Aberdeen Proving Ground, Maryland and is
therefore the Selected Remedy.
The Selected Remedy involves the installation of a new, multi-layered
cap in accordance with MDE requirements for Sanitary Landfill Closure
(COMAR 26.04.07-21). The design features of this capping system shall
include:
Compacted semipervious earthen material (minimum 2 feet thick)
over the entire landfill area;
Regrading material to provide a minimum of 4 percent slopes
over the landfill;
A geosynthetic membrane with a minimum thickness of 20 mil and
maximum permeability of IxlO'10 cm/a as the impermeable layer;
A sand drainage.layer with an in-place permeability greater
than IxlO*1 cm/a and minimum thickness of 1 foot (which would
include a network of drainage pipes to promote stormwater
drainage);
Final earthen cover (minimum 2 feet thick) with vegetative
stabilization; and
Gas venting.
.Figure 6 provides an illustration of a typical cross-section for the
Selected Remedy. Table 13 provides a detailed breakdown of the costs
47
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MINIMUM 4% SLOPE
MINIMUM 4% SLOPE
GRASS
COMPACTED EARTHEN MATERIAL
J(FINAL COVER)
FILTER
FABRIC
. SYNTHETIC
GEOMEMBRANE
^EXISTING COVER;
&u^^
LANDFILL WASTE
NOTE: FIGURE NOT TO SCALE
FIGURE 6
TYPICAL CROSS-SECTION FOR
ALTERNATIVE No. 5
MDE CAP UTILIZING A SYNTHETIC GEOMEMBRANE
SOURCE: Dimei & Moore, I992b
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TABLE 13
COST ESTIMATE FOR ALTERNATIVE 5
MDE SANITARY LANDFILL CAP UTILIZING SYNTHETIC GEOMEMBRANE
MICHAELSVILLE LANDFILL
Capital Costs
Item
Site Preparation"
UXO clearance, site clearing, grubbing, chipping,
hauling, and disposal
Site grading material, hauling, and compaction (1.25 feet)
Proofrolling
Final cover material, hauling, and compaction (2 feet)
Geomembrane, installed, tested
Drainage material, hauling (1 foot of sand)
Testing of sand borrow source'
PVC pipe, fittings, and geotextile filter fabric
for drainage system (installed)*
Geotextile filter fabric, installed
Topsoil (2 feet, installed)
Revegetation
Vent system
Vent wells
Vent pipe and risers (4-inch id PVC)
Trench excavation
Gravel backfill
Geotextile filter fabric, installed
Mobilization/demobilization"4
CAPPING SUBTOTAL
CONTINGENCY (20%)
TOTAL, CONSTRUCTION COST
DESIGN, ENGINEERING, AND CONSTRUCTION
MANAGEMENT (25%)
TOTAL CAPITAL COST
Rate
17.71/c/
0.05/cy
17.71/c/
4.19/sy*
17/cy
1.28/sy
16.99/cy*
0.043/sf
650 ea
2.70/lf
4.58/cy
12.63/c/
1.28/sy
Unit
50,400 cy"
96,800 sy
80,600 cy"
96,800 sy
35,400 cy
96,800 sy
80,600 cy"
871,200 sf
2
5,200 If
2,600 cy"
2,200 c/
8,000 sy
Cost
1991 <$)
782,000
892,600
4,800
1,427,400
405,600
601,800
800
44,000
123,900
1,369,400
37,500
1,300
14,000
11,900
27,800
10,200
106.400
5,861,400
1.172.300
7,033,700.
1.758.400
8,792,100
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TABLE 13 (Cont'd)
Annual O&M Costs
Hem
Inspection and Maintenance/Repair of Cap
Routine inspections and minor repairs for
the cap and cover system (SO days/year)
Rate
247.60/day
0.00145 sf
Unit
50 days
871,200 sf
Cost
1991 fSl
124,100
10.
in
O
O&M SUBTOTAL
CONTINGENCY AND OVERHEAD (20%)
ANNUAL O&M COST
NET PRESENT WORTH FOR ALTERNATIVE 5
(Total capital cost + total O&M cost)
22,500
4.500
27,000
9,207,200
' Means, 1990 (provides 1991 costs) unless otherwise indicated. City multiplier was used because it applies equally to all costs.
" Extra material for compaction and spillage is included. This extra quantity is assumed to be 25% of total compacted cubic yardage
for clay, topsoil, and site grading material; 10% for sand; and 5% for gravel (EPA, 1986).
c Includes collection and testing of two representative samples for moisture, Atterberg limits, gradation, compaction, 4-poini
permeability. Costs are from Dames & Moore.
d Borrow material costs were obtained from local vendors.
' EPA, 1986 (updated to 1991 costs).
' Includes collection and testing of two representative samples for gradation and compaction.
Note: cy = cubic yard; sf = square feet; ea = each, sy = square yard.
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associated with it. Some changes may be made to the Selected Remedy as a
result of the remedial design and construction processes. In general, such
changes will reflect modifications resulting from the engineering design
process.
As discussed previously in this ROD, the geosynthetic membrane and the
sand drainage layer shall be designed, inspected, and maintained to achieve
permeabilities of no more than IxlO'10 cm/sec and IxlO'3 cm/sec respectively.
During the design of the cap, an O&M manual will be developed. At a
minimum the manual shall include provisions for repairs to the cover as
necessary to correct the effects of settling, subsidence, erosion, etc.,
the cultivation of natural vegetation (grasses and weeds) on the topsoil to
prevent erosion, and 5-year reviews under Section 121(c) of CERCLA,
42 U.S.C. S 9621 (c), because the Selected Remedy will result in
contaminants remaining on-site.
X. STATUTORY DETERMINATIONS
The Army's responsibility under the FFA is to implement remedial
actions which will protect human health and the environment. Section 121
of CERCLA, 42 U.S.C. § 9621, also establishes several other statutory
requirements and preferences. The Selected Remedy must be cost effective,
utilize a permanent solution and implement alternative treatment
technologies or resource recovery technologies to the maximum extent
practicable. The Selected Remedy must comply with all applicable or
relevant and appropriate requirements set forth by State and Federal
environmental regulations, unless such requirements are waived in
accordance with CERCLA Section 121, 42 U.S.C. § 9621. Finally, the Army
must attempt to satisfy the statutory preference for remedial actions that
permanently reduce the toxicity, mobility, and volume of the site-related
wastes. The following sections discuss how the Selected Remedy meets the
statutory requirements and preferences set forth by Section 121 of CERCLA.
Protection of Hunan Health and the Environment
The risk posed by MLF and addressed in this ROD is potential exposure
to and/or transport of contaminants that may be associated with surface
water runoff or surface water infiltration and subsequent leachate
generation. The Selected Remedy will eliminate this risk by covering the
buried MLF waste material with a capping system designed to prevent surface
water infiltration and/or contact with potential contaminants. Exposure
levels will be reduced to within the 10" to 10"7 range within which EPA
manages, carcinogenic risk and the Hazard Indices for noncarcinogens will be
less- than one. Implementation of the Selected Remedy is not expected to
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result in any adverse ahort-term risks or cross-media impacts.
Compliance With Applicable or Relevant and Appropriate Requirements
The Selected Remedy will comply with all the ARARs in Table 14. No
ARAR waivers will be used. Table 14 is organized according to action-
specific and location-specific ARARs. There are no chemical-specific ARARs
relevant to this remedy.
Cost-Effectiveness
The Selected Remedy provides a level of overall effectiveness
comparable to or greater than that provided by other remedies at the lowest
cost.
The estimated Present Worth Cost of the Selected Remedy is $9,207,200,
which includes 30 years of O&M at the site. The O&M activity is expected
to include routine inspections of the cap, cutting and maintaining the
vegetation on the cap, and minor repairs to the cap to ensure its long-term
effectiveness.
Utilization of Permanent Solutions and Alternative Treatment (or Resource
Recovery> Technologies to the Maximum Extent Practicable fMEPl
The Army has determined that the Selected Remedy represents the
maximum extent to which permanent treatment technologies can be utilized in
a cost-effective manner for remediation of MLF.
Of the alternatives' that comply with ARARs, the most permanent
solution would be to remove the source from the site and place the waste in
a secure landfill. The other capping and excavation alternatives would
provide adequate long-term effectiveness and permanence, but the capping
alternatives would not address the potential for continued migration of
contaminants to the water table, Alternative 2A would not address the
potential for degraded ash material to leach contaminants, and Alternative
3A would not address the potential for the lined landfill to leak over
time.
The capping alternatives and Alternative 3A would reduce mobility of
contaminants at the site, but would not reduce toxicity or volume because
the wastes remain on-site. Alternative 1A would remove the waste from the
site, thus providing the greatest reduction of toxicity, mobility, and
volume. However, the liability for the waste is merely transferred to
another location under this alternative. Alternative 3A would reduce the
volume, but does not address the potential for degraded ash to leach
contaminants to the water table over time.
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TABLE 14
REVIEW OF POTENTIAL ACTION-SPECIFIC AND LOCATIONAL ARARs
FOR MICHAELSVILLE LANDFILL SELECTED REMEDY
Environmental Laws and Regulations
ACTION-SPECIFIC
I. RCRA
A. Subtitle C requirements
1. Closure and postclosure
(40 CFR Part 264, Subpart G)
2. Groundwater monitoring and
protection
(40 CFR Part 264, Subpart F)
3. Transportation standards
(40 CFR Part 263)
4. Landfill standards
(40 CFR Part 264, Subpart N)
5. Land Disposal Restrictions
(40 CFR Part 268)
H. Clean Water Act
A. Clean Water Act Requirements
(40 CFR Parts 230-233)
HI. U.S. Army Corps of Engineers
A. Clean Water Act Requirements
Section 404 Nationwide Permits
(33 CFR Part 330, Appendix A #38)
IV. Clean Air Act
A. National Ambient Air Quality Standards
(NAAQS) (40 CFR Part 50)
B. National Emission Standard for Hazardous
Air Pollutants (NESHAPS)
(40 CFR Part 61, Subpart M)
Consideration as an ARAR
Waste materials will be contained in place,
requiring a cover.
Hazardous wastes may exist. These wastes will be
capped in place.
Shipments of hazardous waste off-post could be
necessary under the MLF Selected Remedy.
Design requirements for a hazardous waste landfill
cap will be considered under MLF Selected
Remedy.
These restrictions may apply if certain hazardous
wastes are excavated and disposed in a landfill.
These restrictions also apply to leachate and other
hazardous by-products which may be produced.
The Selected Remedy will affect wetlands defined
under this act. New wetlands will be created to
offset disturbed wetlands.
The Nationwide Permit for NPL Site is exempt
under CERCLA. In any event, the wetlands
impacted by the Selected Remedy will be replaced.
The Selected Remedy involves earthmoving
operations which may result in emissions to air.
The Selected Remedy involves earthmoving
operations which may result in emissions to air.
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TABLE 14 (Cont'd)
REVIEW OF POTENTIAL ACTION-SPECIFIC AND LOCATIONAL ARARs
FOR MICHAELSVILLE LANDFILL SELECTED REMEDY
Environmental Laws and Regulations
Consideration as an ARAR
C. National Emission Standard for Hazardous
Air Pollutants (NESHAPS)
(40 CFR Part 61, Subpart M)
V. Occupational Safety and Health
Administration (OSHA) Requirements
A. Requirements for workers at remedial
action sites (29 CFR Part 1910)
VI. U.S. Department of Transportation (DOT)
Regulations (49 CFR Parts 170-179)
VII. State of Maryland
A. Maryland Air Pollution Control
Regulations
(COMAR26.11.01-.23)
B. Maryland Sanitary Landfill Closure
Regulations
(COMAR 26.04.07.21)
. *
C. Maryland Erosion and Sediment Control
Regulations
(COMAR 26.09.01)
LOCATION-SPECIFIC
I. RCRA
A. Subtitle C requirements
1. Location standards
(40 CFR Part 264, Subpart B)
EL Statement of Procedures on Flood Plain
Management and Wetlands Protection
(40 CFR Part 6, Appendix A, and Executive
Orders 11988 and 11990)
III. Conservation of Wildlife Resources (Fish ,-.i
Wildlife Coordination Act)
(50 CFR Parts 400-499)
The Selected Remedy involves earthmoving
operations which may result in emissions to air.
Any remedial action onsite must be performed in
accordance with applicable OSHA standards.
Contaminated soil and other waste materials could
be transported off-post under the Selected Remedy.
The Selected Remedy involves earthmoving
operations which may result in the discharge of
pollutants to the atmosphere.
This regulation provides design requirements for the
closure (capping) of sanitary waste landfills.
Excavation, dredging, and backfilling activities at
the site may cause increased erosion and sediment
runoff requiring the application of control measures
during remediation.
Portions of streams downgradient of the site may be
located within the 100-year flood plain, though none
are located in a seismic area, as defined by the
regulations.
Portions of APG-AA are considered wetlands. The
Selected Remedy must consider adverse impacts to
these areas. MLF site is not within the 100-year
flood plain.
The bald eagle is an endangered species known to
be present at APG.
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The capping alternatives provide a much greater level of short-term
effectiveness than the excavation alternatives because the waste would
remain in place and would not pose an increased threat to human health or
the environment during excavation activities.
The capping alternatives and Alternative 3A would be more easily
implemented than Alternatives 1A and 2A. Alternative 1A would require
finding an enormous volume of secure landfill capacity, while Alternative
2A would require a great deal of time to implement.
The capping alternatives are much less costly than the excavation
alternatives. Of the capping alternatives, Alternative 5 is the most cost
effective.
Of the five primary balancing criteria discussed immediately above,
the first two (long-term effectiveness and permanence and reduction of
toxicity, mobility, or volume) were relatively equal among the capping and
excavation alternatives, and therefore, offered little comparative
information upon which to base a decision. The short-term effectiveness,
implementability, and cost criteria, however, afforded sufficient contrast
among the alternatives to facilitate a clear decision. The Selected Remedy
will provide a high level of short-term effectiveness and a high level of
implementability at a lower cost. The community accepted this selection
based on the issues of short-term effectiveness and implementability. EPA
and MOB support the Selected Remedy.
Preference for Treatment as a Principal Element
None of the capping alternatives considered for the MLF site employ
treatment because no treatment technologies are currently available that
would eliminate the risks associated with MLF in a cost-effective manner.
The Selected Remedy is the most cost-effective and technically feasible
approach'to eliminate site risks.
This remedy utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable for this site. However,
because treatment of the principal threats of the site was not found to be
practicable/ this remedy does not satisfy the statutory preference for
treatment as a principal element of the remedy. The size of the landfill,
excessive costs associated with the excavation alternatives, and the
difficulties of implementing the excavation alternatives preclude a remedy
in which contaminants could be excavated and treated effectively. The
Selected Remedy is consistent with the Superfund program policy of
containment, rather than treatment, for wastes that do not represent a
principal threat at the site and are not highly toxic or mobile in the
environment.
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The Proposed Plan for MLF was released for public comment in March
1992. The Proposed Plan identified Alternative 5, Installing a New Cap in
Accordance with MDE Requirements for Sanitary Landfill closure Using a
Geosynthetic Membrane, as the preferred alternative. The Army reviewed all
written and verbal comments submitted during the public comment period.
Upon review of these comments, it was determined that no significant
changes to the Selected Remedy, as it was originally identified in the
Proposed Plan, were necessary.
XI. RESPONSIVENESS SUMMARY
From March 18, 1992 to May 4, 1992, EPA held a public comment period
on the HGA, the FFS, and the Proposed Plan for the MLF in the Aberdeen Area
of APG. A public meeting on the Proposed Plan was held on April 9, 1992,
the transcript of which is part of the Administrative Record for this site.
This responsiveness summary summarizes comments on the Proposed Plan by
interested parties and provides the Army's responses to the comments.
This responsiveness summary is divided into the following sections:
Overview
Background on Community Involvement
Summary of Comments Received during Public Comment Period and
Agency Responses
Remaining Concerns
Overview
At the time of the public comment period, the Army had already
endorsed a Preferred Alternative for MLF. EPA and MOB concurred on the
Army's recommended capping alternative to prevent precipitation from
infiltrating the waste and subsequently mobilizing contaminants which can
leach to the ground water. The Preferred Alternative specified in the
Record of Decision (ROD) consists of the following:
- Installing a new, rauItilayered cap in accordance with MDE
requirements for sanitary landfill, using a geosynthetic
membrane. The design features of this system include a minimum
2 feet of compacted earthen material over the existing landfill
cover; a geosynthetic membrane (minimum thickness 20 mil) over
the earthen material; 12 inches of sand drainage material
imbedded with perforated drainage pipes over the membrane; and
a final earthen cover (minimum 2 feet thick) with a 4 percent
minimum slope and vegetative stabilization.
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Installing surface water controls to accommodate seasonal
precipitation.
- Installing a methane gas venting system within the cap system.
Background On Community Involvement
There has been moderate community interest in MLF due to its proximity
to public drinking water supplies. Although community representatives
would prefer a permanent solution which removes the source of contamination
from the site, they recognize that limited technology, high cost, and human
health risks associated with excavation and incineration of the waste
material precludes implementation of these options.
Summary Of Comments Received During The Public Comment Period And Agency
Responses
Comments Received from Ms. Helen Richick, Technical Review Committee,
February 28, 1992
I. EXCAVATION OF WASTE
Comment 1-1
Response
Has the Army considered the excavation of the entire
Michaelsville Landfill and/or identification of "Hot
Spots" and subsequent excavation of these areas?
Originally, the Focused Feasibility Study (FFS) for a cap
and cover system at Michaelsville Landfill (MLF) did not
examine excavation of the waste material because it was
deemed too costly and a ground water Remedial
Investigation and Feasibility Study (RI/FS) was planned
for the landfill. In addition, there would be
considerable risk to the public and site workers if the
waste was excavated and exposed. In February 1992, at
the Army's request, Dames & Moore initiated a study to
evaluate the following three excavation alternatives for
MLF:
Alternative 1A - Excavating and hauling the waste off-
site;
Alternative 2A - Excavating and incinerating the waste;
and
Alternative 3A - Excavating the waste, lining the cavity,
replacing the waste, and capping the
landfill.
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As part of this study, a cost estimate for each
excavation alternative and the advantages/disadvantages
of each alternative were presented. The results of the
study were submitted to the Army on March 4, 1992 and the
report was included in the FFS for MLF.
Although the three excavation alternatives would all be
protective of human health and the environment after
implementation, each one would create additional exposure
pathways during implementation. They would cause an
increased potential for human health exposure during the
excavation of the waste, during which time local
residents, APG workers, and site workers face an
increased potential for inhalation of and dermal contact
with the concentrated contaminants as they are disturbed,
excavated, and perhaps released to the environment. In
addition, the excavation process may create additional
pathways for environmental degradation if materials are
released during transport. Implementation of the
excavation alternatives would create a risk to human
health and the environment over a long period of time.
The excavation alternatives are costly and currently, the
contaminants from this site are not highly toxic or
mobile in the environment or ground water. The
installation of a cap over the landfill will reduce the
threat of contaminants within the landfill from becoming
highly mobile in the environment or ground water. The
environmental net gain of implementing the excavation
alternatives is not high relative to the costs associated
with the alternatives. Therefore, the excavation
alternatives were not considered further.
There is no knowledge of "hot spots" within MLF as
historically, only domestic trash and refuse were known
to have been placed within the landfill. Hot spots are
usually identifiable if someone has identified that drums
of hazardous waste or large containers were disposed of
at specific locations within the landfill.
Comment 1-2
Response
Is the Army considering the option of relocating MLF to
a properly sealed site?
This option was addressed as Alternative 3A by Dames &
Moore in the attached Feasibility Assessment of
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Comment 1-3
Response
Excavation Options at MLF. This alternative involves
excavating the waste, storing the waste in a temporary
impoundment while a liner system is installed in the
excavation cavity, returning the waste to the lined
cavity and capping the landfill. The liner will meet or
exceed MDE requirements for a sanitary landfill and the
cap will be constructed using a modified MDE design as
discussed in the MLF Focused Feasibility Study. By
isolating the source of contamination, Alternative 3A is
protective of human health and the environment. However,
Alternative 3A is not a source removal operation.
Therefore, the need for ongoing operations and
maintenance expenditures (i.e., management of leachate)
will continue. Since Alternative 3A involves leaving the
waste in place, any ground water remediation will likely
be continued for at least 30 years. In addition, this
alternative poses significant risks to human health and
the environment during excavation activities. The cost
of Alternative 3A is $21,825,000. For this reason, along
with implementation problems, Alternative 3A was not
selected.
Has the Army considered treating the waste on-site (i.e.,
using a mobile unit)?
The incineration of MLF'a waste using an on-site rotary
kiln incinerator was considered under Alternative 2A in
Dames & Moore's Feasibility Assessment of Excavation
Options. Alternative 2A involves the excavation of the
entire volume of waste in MLF, the transport of the waste
to an on-site mobile rotary kiln incinerator, and
incineration of the waste. The incinerator would be
housed within a 3 to 4-acre building which includes
processing and storage areas. Approximately 25 percent
of the initial volume would remain as ash. The ash would
be nonhazardous particularly if the ash is stabilized
first to immobilize the heavy metals. The ash could be
returned to the ground as fill for the cavity remaining
after excavation. The incinerator would produce an ash
byproduct and air emissions.
Because incineration involves source removal, no ongoing
operations and maintenance costs are anticipated under
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Alternative 2A. However, ground water remediation will
still be required, although for a reduced period of time
(approximately 10 years). The cost for Alternative 2A is
$182,795,000. Alternative 2A is protective of human
health and the environment in that it involves removal
and destruction of the source of contamination. However,
this alternative was not selected because of the
significant risks associated with disturbing the waste
and transporting it to the on-site incineration unit, the
need for additional air pollution controls, the high
costs due to the energy requirements for the incineration
unit, and the number of years the unit must operate to
treat the entire volume of waste in the landfill. In
addition, the excavation of the landfill will increase
the risk of mobilization and leaching of contaminants
into the ground water.
Comment 1-4
Response
Is it feasible to treat contaminated soil and waste on-
site by the use of a portable incinerator? The
incinerator could be utilized at other Solid Waste
Management Unit remedial actions on APG. A combination
clay and synthetic liner could be prepared to receive
waste.
There is currently a well developed technology for the
use of an on-site mobile incinerator to treat
contaminated soil and waste. The option of using an on-
site incinerator at MLP was evaluated under Alternative
2A and found to be effective in removing and destroying
the source of contamination. However, several
disadvantages to this option were identified that
outweigh the overall effectiveness of this option.
Significant risks are associated with disturbing the
waste and transporting it to the on-site incineration
unit and the process may produce air emissions that
violate local air regulations, resulting in the need for
additional air pollution controls. In addition, the
stabilized ash left in the landfill may break down over
time and release heavy metals to the environment in the
future. Lastly, the cost to implement this alternative
is extremely high due to the energy requirements for the
incineration unit and the number of years the unit must
operate to treat the entire volume of waste in MLF. The
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cost of this alternative is estimated to be $182,795,000.
Comment 1-5
Response
What technology is available today for the successful
incineration of landfill waste?
The most commonly used incineration technologies
(according to the Standard Handbook of Environmental
Engineering by Robert A. Corbitt) are rotary kiln, single
chamber/liquid injection, multiple hearth, and fluidized
bed. Of these technologies, only the rotary kiln method
is able to accommodate the soil and bulk wastes which
would be excavated from MLF. The single chamber/liquid
injection process requires liquids and slurries that can
be pumped; the multiple hearth process requires sludges
and granulated solid wastes; and the fluidized bed
process requires organic liquids, gases and granular or
well-processed solids. Therefore, the rotary kiln method
is best suited for MLF.
Comment 1-6
Response
Can these incineration techniques be used for the
remediation of MLF?
As was stated in the response to Comment 1-4, the option
of using an incinerator for the remediation of MLF'a
wastes was found to be highly effective in meeting the
overall site objective of removing and destroying the
source of the contamination on-site. But, based upon
risk evaluation and cost effectiveness, the incineration
of the landfill waste was determined to be impracticable.
According to EPA Guidance on Conducting Remedial
Investigations at Municipal Landfills, February 1991, the
most practicable remedial alternative for municipal
landfills today is containment. Very few excavations of
landfills the size of MLF have been conducted at the
present time.
Comment 1-7
Response
Does the Army anticipate any problems in maintaining the
new cap and cover system once in place?
Long-term maintenance of the cap will not be a problem
for the Army since MLF is accessible for investigations
and study. After completion of the cap construction, the
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Army shall comply with State of Maryland Sanitary
Landfill Closure Monitoring and Maintenance requirements
(COMAR 26.04.07.22 G-J) in order to maintain the
integrity and effectiveness of the new cap. This will
include making repairs to the cap as necessary to correct
the effects of settling, subsidence, erosion, or other
events.
Comment 1-8
Response
Did restricted access to MLF in the past cause some of
the problems with the present cover? What was the cause
of the present cover's loss of integrity (lack of
sufficient maintenance)?
The inadequacy of the present cover was due to the
original construction of the cap and lack of sufficient
maintenance, not restricted access. The present cap,
constructed in 1981-1982, met the regulatory requirements
for installation at that time and was maintained in
accordance with the normal practices of that time, even
though by today's standards, the cap is unacceptable. By
the time the State of Maryland Sanitary Landfill Closure
Monitoring and Maintenance requirements came into effect
{COMAR 26.04.07.22, March 1988), a loss in the integrity
of the cover had occurred from the effects of settling
and vegetative growth. The current level of restriction
in the area surrounding MLF should not preclude normal
maintenance of the new cover.
II. METHANE GAS
Comment II-l
Response
Could the activities on the test ranges adjacent to and
in close proximity to MLF have a negative impact upon the
landfill?
Range activities adjacent to MLF are unlikely to have a
negative impact upon the landfill since there is
considerable distance separating the landfill from the
range testing area. The chances of a stray munition
landing on the landfill are very small and historically,
negative impacts as a result of the nearby range, have
not occurred.
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Comment 11-2
Response
Has the Army considered the potential for negative
impacts should munitions inadvertently land near or on
MLF; disturbing the integrity of the cap/cover, leachate
collection system, and methane gas collection system?
Although the possibility of a round impacting MLF is
remote, if a stray round should land on the landfill the
Army would quickly retrieve the round and repair the cap
(as required by State of Maryland Sanitary Landfill
Closure Monitoring and Maintenance requirements, COMAR
26.04.07.22). More importantly, if damage of any nature
should occur (i.e. weather, round, etc.), the Army is
prepared to repair the cap, leachate collection system,
or methane gas collection system immediately to maintain
its integrity.
Comment II-3
Response
A subsequent field fire occurred on a portion of MLF,
apparently unrelated to range fires. What caused the
fire at MLF last year?
During November 1991, there were two fires on the test
range adjacent to MLF. The first fire, which occurred in
the early part of November, was confined to the adjacent
range testing area. On November 20, 1991, the second
fire began on the adjacent range testing area and
extended approximately 30-40 feet onto the east portion
of the landfill before being extinguished. Both fires
started due to a combination of dry surface vegetation
and range testing and caused only surface vegetation
damage.
Comment I1-4
Response
Was the fire related to dry conditions and/or a result of
range testing?
The two range, fires that occurred in November 1991 were
started by a combination of dry vegetative conditions and
range testing.
Comment I1-5
Could the fire have been fueled additionally by
subsurface methane gas at MLF? Could the levels of
methane gas at MLF create an explosive condition?
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Response
Methane at elevated levels can be a source of fuel for an
explosion or fire, particularly in confined or sealed
areas. An explosion due to the igniting of methane gas
at MLF is highly unlikely since the gas coming up to the
surface is quickly dissipated due to atmospheric
conditions. The fire at MLF was confined to the surface
vegetation, not the subsurface materials. In addition,
the levels of methane offgasing from the landfill would
have to be within 25% of the Lower Explosive Limit (LEL)
for methane (5% mixture of methane in air by volume) in
order to trigger an explosion (COMAR 26*04.07.21,
Sanitary Landfill Closure).
Comment II-6
Response
Is the branch of the Army responsible for range testing
activities appraised of the zone of methane migration?
Is there a possibility that during range testing
activities, stray munitions may land on MLF?
The U.S. Army Combat Systems Test Activity (CSTA) is
responsible for range operation and is aware of MLF and
its investigation. The migration of methane is minimal
and would have little or no impact on CSTA operations.
CSTA will be informed that periodically methane has been
observed in the immediate vicinity of MLF. Although the
zone of methane migration varies, the zone is limited to
the immediate area around MLF and will not be impacted by
range testing activities. As stated in our response to
Comment II-l, the probability of a stray round landing on
the landfill is remote.
Comment II-7
Response
Should an additional buffer zone be established to
prevent potential negative impacts should future range
fires occur?
Currently, there is a 500-foot buffer zone of grassy
vegetation between the south side of MLF and Trench
Warfare Road (which runs parallel to the landfill and the
range testing area). This buffer zone is not part of the
range testing area and the Army considers the zone to be
adequate for the prevention of negative impacts from
range fires. The required maintenance of the new cover
by the Army and immediate fire control response will
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assist in preventing potential negative impacts on MLF
cover should a range fire occur.
III. AIR POLLUTION
Comment III-l
Response
Are there any air pollution concerns at MLF, Fire
Training Area (FTA), or Phillips Army Airfield Landfill
(PAALF)? If so, what type of monitoring is being
conducted and how often?
Air monitoring, using organic vapor analyzers, ionization
detectors and explosive meters, has been performed during
every investigation conducted at these sites and has not
indicated any levels of air pollutants above the
permissible exposure limits. Although air pollution
concerns are not expected at these sites since they do
not release airborne contaminants, air monitoring using
the above instrumentation will still be conducted during
any future investigations.
Comment II1-2
Response
Is it possible that a fire on MLF would create a
hazardous air pollution problem, causing if not long-term
then short-term health hazards for APG employees working
in that area?
It is not expected that a fire on MLF would create any
more of a pollution hazard than a normal grass or brush
fire since the burning would be confined to the surface
vegetation. The cap would prevent any fires from
reaching subsurface wastes.
IV. GROUND WATER
Comment IV-1
Response
In MLF Hydrogeologic Assessment, Volume I, page 37,
paragraph 1, a portion of the sentence is missing.
Please provide information.
Due to security reasons, this sentence was removed from
the Hydrogeologic Assessment. This sentence had no
impact on the study at MLF.
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Comment IV-2
Response
In reference to MLF, the FTA, and PAALF, if Harford
County, Maryland or the Bay Region in general, experience
a long period of drought conditions, would this have a
potential negative impact on the flow of the ground
water? Would this influence ground water recharge areas?
A long drought would affect ground water levels in the
entire Harford County area by decreasing them and could
influence the direction of flow depending on pump rates
and the hydrogeology of the area. Recharge areas in the
entire County would also change because of reduced
surface water flows. The Army plans to use numerical
modeling to examine the specific effects of a long
drought or other hydrologic changes at this site.
Comment IV-3
Response
Are ground water studies/modeling being conducted to show
potential ground water movement scenarios at the FTA,
MLF, and PAALF, should off-post well pumping rates
increase?
Plans for additional ground water studies and ground
water modeling have been included within the scopes of
work for Remedial Investigation and Feasibility Studies
at the FTA and MLF. To increase drinking well pumping
rates the Department of Natural Resources requires a
permit. The probability of granting a permit for the
withdrawal of large amounts of water that could
potentially alter ground water movement in the
surrounding areas is very small.
Comment IV-4
Response
MLF has been in existence for approximately 22 years.
Taking into consideration the known level of
contamination presently at MLF, is it considered by
experts to be a relatively short period of time for this
amount of contamination to have contributed to ground
water and/or surface water degradation?
There are no established criteria for predicting the
period of time in which landfill leaching contributes to
ground water and surface water. There are several
factors that influence the period of time in which
contamination of the ground water may be observed at any
one point. These include the amount of water
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infiltrating into the landfill; the constituents within
the landfill; the form in which the wastes were stored
when placed in the landfill; how much contact exiata
between the landfill and the aquifer; water-table
conditions; and the rate of ground water flow. Because
of such variability between one landfill and another,
there is no means of determining, by comparison with
similar-type landfills, whether the contaminants from MLF
reached the ground water or surface water in a relatively
short period of time.
Comments Received from Ms. Helen Rj.chl.ck, Technical Review Committee,
April 9, 1992
Comment I
Response
I request consideration be given to continue such
monitoring (of water level elevations for PAALF, MLF,
City of Aberdeen and Harford County wells) if it is not
already planned as part of future ground water studies.
The Army is developing work plans to conduct well water
level measurements for PAAFLF, FTA, MLF and all
appropriate wells located within the APG boundary.
Comment II
Response
Could the fact that the Trench Warfare Road side of the
landfill is more contaminated with iron, chloride and
PCS's than other parts of the landfill be the result of
waste being in direct contact with ground water? Are
there monitoring wells on the range next to MLF? Has
consideration been given to the possibility of past and
present range activities contributing to ground water
contamination?
Iron and chloride are typical non-hazardous components of
landfill leachate. They are limited for drinking water
due to their effect on the appearance and taste of the
water (aesthetic reasons). Therefore, the increased
presence of these materials on the Trench Warfare side of
the landfill does not give any information about whether
or not the water table is in direct contact with the
waste. Because PCB's are liquid and are known to be
present in MLF, their presence also does not provide
information on this issue. The conclusion which might be
drawn is that the ground water does flow towards the
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Trench Warfare side of the landfill. There are
monitoring wells on all sides of MLF. Results from the
August 1991 round of ground water sampling did not
indicate any adverse impacts from range operations
adjacent to MLF. Thus, the Army has concluded that no or
insignificant impact from adjacent range operations to
the ground water has occurred.
Comment III
Response
Will it be necessary to treat the ground water beneath
MLF long-term? Should the excavation and incineration of
MLF occur in the future, would the contaminated ground
water beneath MLF still require long-term treatment?
It is impossible to determine whether long-term ground
water treatment will be necessary beneath MLF until the
Remedial Investigation for Operable Unit 2 is completed.
However, if the ground water is found to require
treatment, then the ground water would still require
treatment whether the waste was removed or not because
excessive contaminants would already be in the ground
water.
Comment IV
Response
APG back-up, wells indicate low levels of contamination.
Has the Army/EPA determined the source of the
contamination in these wells? Does the Army/EPA suspect
the contaminated aquifer beneath MLF to be a potential
source of contamination to the wells? How many times
(how often) have the APG back-up wells been utilized in
an emergency or for an alternate water source? What were
the dates wells were used? Does the Army/EPA have
concern about pulling contamination from MLF should it be
necessary to withdraw a major amount of water from these
wells? Has consideration been given to installing
monitoring wells between MLF and APG back-up wells? What
is the off-site extent of methane migration?
The Army is not aware of any chemical analyses done of
the APG backup wells. Thus, APG has not determined that
the wells are contaminated or that there is a source of
contamination. The backup wells are run infrequently for
short periods. MLF is a potential source of chemicals
for the backup wells if they are used.
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The installation of monitoring wells between MLF and the
back-up wells is being considered as part of the ground
water source Remedial Investigation for Operable Unit 2
of MLF. Although the distance methane from MLF has
travelled has not been quantified, the existing gas
venting wells located on and around MLF have yielded
relatively low levels of methane gas, suggesting the
migration is minimal. This is not surprising because MLF
has been virtually uncovered since 1980, allowing the
methane to escape directly to the atmosphere vertically
without migrating horizontally.
Comment V
Response
Has the Army given consideration to the fact that MLF is
a young landfill in which settling will occur in the
future and cause the landfill to shift, creating,in time,
enough stress to break the geomembrane?
MLF has been open to the weather for over ten years.
During this time, the majority of settling which will
occur has occurred. However, when the landfill is
capped, the additional weight of the cap may cause
further settling. This settling is taken into account
when designing the landfill. Laboratory tests are
performed on the soil and the liner to simulate the
stresses which may be encountered due to settlement. The
results of this testing enable the designers to ensure
the liner is adequate to withstand the worst-case
stresses which may occur as the result of settling. The
MLF cap will be maintained and repaired when and if
necessary.
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