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

-------
                                         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.

-------
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
7. AuMeifr)
». Pertomfrig Orgitazrten M»m» mi Addrem

U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
3. RedpMfiCe >CT»Mion Mo.
S. Report Dm
06/30/92 ' i
c.
•. P«rtormlrwOrB«nli»tk>nHept.No.
ia ProjicVTsak/Woifc IMt No.
11. CoancKOorOnnltQNa. i
(C)
(0)
11 Type o( Report tPwtodCowrad
800/000
M.
 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

-------
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.

-------
                         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

-------
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

-------
            RECORD OF DECISION



          MICHAELSVILLE LANDFILL




             Operable Unit One




U.S. Army Aberdeen Proving Ground/ Maryland




             DECISION SUMMARY

-------
                             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

-------
                            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

-------
                              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

-------
                          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.

-------


                  ^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

-------
                                                                                         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

-------



                                                                                           .
                                                                   LEGEND:

                                                                     46I
                                                                         TOPOGRAPHY CONTOURS
                         TOWER
                    -^BUILDING
                          287
                                                                                           	 PERIMETER
                                                                                           .  OF LANDFILL
                                     TRENCH WARFARE ROAD
                                                   FIGURE 3
                                            MICHAULSVILLE LANDFILL
                                                   SITEMAP
SOURCE ICF. 1991

-------
      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

-------
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.

-------
                     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

-------
      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)./

-------

                                                                      Bara Earth. Mowed or
                                                                      Developed Land
                                                                      Wafland
SOURCE: ICF. 1991
                                         FIGURE 5
                               HABITAT CHARACTERISTICS OF
                              MICHAELSVILLE LANDFILL AREA

-------
      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

-------
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

-------
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

-------
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

-------
                                    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

-------
                                               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

-------
      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 1988—one sample, September 1988—one sample, April 1989—four samples,
and October 1989—four 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

-------
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

-------
                          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

-------
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

-------
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

-------
                                                    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.

-------
                                                                   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.

-------
                                                                  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

-------
                                                           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.

-------
                                                           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.

-------
                                                                  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.

-------
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

-------
(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

-------
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

-------
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

-------
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

-------


         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

-------
                                                       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

-------
                                                              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.

-------
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
                                    51

-------
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.
                                    52

-------
                                         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.
                                              S3

-------
                                     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.
                                               54

-------
      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.

                                    55

-------
      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.

                                   56

-------
            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.
                                    57

-------
                 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
                                    58

-------
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
                                    59

-------
                 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
                                    60

-------
                  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
                                    61

-------
                 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.
                                    62

-------
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?
                                    63

-------
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
                                    64

-------
                  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.
                                    65

-------
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
                                    66

-------
                  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
                                    67

-------
                 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.
                                    68

-------
                  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.
                                    69

-------
                               REFERENCES

Dames &  Moore,   1972.    Ferryman Nuclear  Power  Plant.  Unita 1  and  2.
      Environmental Report,  Baltimore Gas and Electric Company, Baltimore,
      MD.

Dames & Moore, 1992a.  Focused Feasibility Study for Michaelsville Landfill
      Cap  and  Cover  System.   Aberdeen  Proving  Ground.  Maryland.  Final
      Report,  prepared  for  U.S.  Army  Corps  of  Engineers,  Baltimore
      District,  Delivery Order No.  1, Contract  No.  DACA31-91-D-Q031.
Dames  & Moore,  1992b.   Proposed  Remedial Action  Plan.  Michaelsville
      Landfill Cap  and  Cover  System,  Aberdeen Proving  Ground. Maryland.
      Draft Report, prepared  for U.S. Army  Corps of  Engineers, Baltimore
      District,  Delivery Order No.  1, Contract  No.  DACA31-91-D-0031.
Edwards, J., and H.J. Hansen,  1979.  "New Data  Bearing on the Structural
      Significance of the Upper Chesapeake Bay Magnetic Anomaly," Report of
      Investigations No. 30.  Maryland  Geological  Survey,  Department  of
      Natural Resources.
Environmental Science and Engineering, Inc.,  1981. Installation Assessment
      of Aberdeen Proving Ground-Aberdeen Area.  Report  No. 301,  prepared
      for the U.S. Army Toxic and Hazardous Materials Agency, Environmental
      and Safety Division,  Aberdeen  Proving  Ground,  MD.
Federal Emergency Management Agency (FEMA), 1983.  Flood  Insurance Rate Mao
      Harford County.  Maryland (Unincorporated  Areas).  Panels 130 (1985),
      135 (1983). 155  (1984).  and 160 (1983). Baltimore, MD.
HELP, 1991.  Hydrogeologic Evaluation of Landfill Performance (HELP) Model.
      U.S.  Environmental Protection Agency, PB-85-100840 and PB-8S-100832,
      Washington, D.C., 1984.   Model was  run by Dames  &  Moore in August
      1991, for Michaelsville  Landfill cap and cover system Alternatives 3,
      4, and 5.
ICF Kaiser Engineers (ICF), 1991.   Preliminary  Risk Assessment for Eight
      Selected Study Areas  at  Aberdeen  Proving Ground.  Maryland.  Draft
      Report, Vol.  II,   Ch.  11,  prepared for  U.S. Army  corps of Engineers
      Toxic  and  Hazardous  Materials  Agency, Task Order No. 11,  Contract
      No. DAAA15-88-D-0009,  January 1991.
Means,  R.S., Company,  Inc.,   1990.   Means  Site Work  Cost  Data.  1991.
      Construction Consultants & Publishers, Kingston,  MD.
Owens/ J.P.,  1969.  "Coastal  Plain Rocks of Harford County,"   The Geology
      of Harford County. Maryland Geological Survey,  Baltimore, MD.

-------
Sisson,  P.A.,   1985.    "Climatic  Summary  for  Aberdeen  Proving  Ground,
      Maryland,"     Reference   Pamphlet  No. 3.,   Atmospheric  Sciences
      Laboratory,  Aberdeen Proving Ground,  MD.

U.S. Environmental Protection Agency (EPA),  1985.  EPA Handbook;  Remedial
      Action at Waste Disposal Sites (revised).

Waterways  Experiment  Station   (WES),   1990.     Michaelsville  Landfill
      Hvdroaeoloaic Assessment, U.S. Army Corps of Engineers, Draft Report,
      prepared  for  Environmental  Management  Division,  Aberdeen  Proving
      Ground, Maryland,  May 1990.

-------