PB97-963908
EPA/541/R-97/091
January 1998
EPA Superfund
Record of Decision:
Aberdeen Proving Ground (Edgewood Area)
Watson Creek Sediment, O-Field OU
Aberdeen Proving Ground, MD
9/23/1997
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RECORD OF DECISION
REMEDIAL ACTION
WATSON CREEK SEDIMENT
(O-FIELD OPERABLE UNIT 3)
FINAL DOCUMENT
DISTRIBUTION RESTRICTION STATEMENT
APPROVED FOR PUBLIC RELEASE:
DISTRIBUTION IS UNLIMITED
2311-B-J
Edge wood Area - Aberdeen Proving Ground, Maryland
September 1997
This document ix intended to comply with the National Environmental Policy Act of 1969.
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DECLARATION FOR THE RECORD OF DECISION
DECISION SUMMARY
SITE NAME AND LOCATION
Watson Creek, O-Field Area, Edgewood Area, U.S. Army Aberdeen Proving Ground, Maryland.
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected action for the Watson Creek sediment, which is
Operable Unit 3 (OU3) of the O-Field Study Area at Aberdeen Proving Ground, MD. The selected action was
chosen in accordance with the requirements of the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), and, to the extent practicable, the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP). 40 Code of Federal Regulations (CFR) 300.430. This
decision document explains the factual basis for selecting the remedy for OU3 and the rationale for the final
decision. The information supporting this remedial action decision is contained in the Administrative Record
for this site.
The State of Maryland Department of the Environment (MDE) concurs with the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from the site, if not addressed by
implementing the response actions 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 (OU) is the third of four that are planned for the site. The first operable unit (OU1)
addresses the contaminated groundwater emanating from Old O-Field. The remedy for OU1, the O-Field
Groundwater Treatment Facility (GWTF), is in the operational stage. The second operable unit (OU2)
addresses the Old O-Field Source Area. The remedy for OU2, the Permeable Infiltration Unit (PIU), is
currently under construction. The fourth operable unit (OU4) consists of the source area and groundwater at
New O-Field. Studies are presently underway to evaluate the risks associated with OU4.
This ROD has been developed for OU3 of the O-Field area. The levels of contamination in the
Watson Creek sediment a.re not a threat to human health. However, localized areas may exist where the
levels of contaminants could potentially adversely affect benthic communities. This remedy addresses the
reduction in adverse effects to benthic communities by limiting disturbance of the sediment which could occur
through future use and development of the affected area
The major components of the selected remedy include:
. Institutional restrictions and maintenance of existing physical security measures;
Prevention of development and disturbance of the site;
. Provision of information for workers and the public concerning the risks present at
the site; and
Long-term monitoring of site conditions.
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The remedy specified herein wilt be one component of the overall remedy for the O-Reld area. This
action will be consistent with any current or planned future remedial actions for the site to the extent
practicable.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, complies with Federal and
State requirements that are legally applicable or relevant and appropriate for this action, and is cost-
effective. This action 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
Because this remedy will result in hazardous substances remaining on site, a review will be
conducted within five years after commencement of the long-term monitoring plan to ensure that the remedy
continues to provide adequate protection of human health and the environment
Edward L Andrews '
Major General, U.S. Army
Commander, U.S. Army Aberdeen Proving Ground
Abraham Ferdas Date
Acting Director
Hazardous Waste Management Division
U.S. Environmental Protection Agency, Region III
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TABLE OF CONTENTS
Section Page
DECLARATION FOR THE RECORD OF DECISION
DECISION SUMMARY
1.0 SITE NAME. LOCATION, AND DESCRIPTION 1-1
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 2-1
2.1 HISTORY OF OLD O-FIELD 2-1
2.2 CLEANUP ACTIVITIES AT OLD O-FIELD 2-2
2.2.1 LTC Dean Dickey's Affidavit 2-2
2.2.2 U.S. Army TEU Surface Sweeps of Old O-Field 2-2
2.3 HISTORY OF NEW O-FIELD 2-3
2.4 PREVIOUS INVESTIGATIONS 2-3
2.4.1 Environmental Survey 2-3
2.4.2 Surface Water Quality Survey „ 2-3
2.4.3 Hydrogeologic Investigation 2-3
2.4.4 Groundwater and Surface Water Sampling, Fall 1991 2-4
2.4.5 Old O-Field Groundwater Treatment Remedy :. 2-4
2.4.6 Old O-Field Source Area Treatment Remedy '. 2-4
2.4.7 O-Field Area Remedial Investigation/Feasibility Study 2-5
2.4.8 Watson Creek Sampling 2-5
2.4.9 Focused Feasibility Study for Watson Creek '. 2-5
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 3-1
4.0 SCOPE AND ROLE OF OPERABLE UNIT OR RESPONSE ACTION 4-1
5.0 SUMMARY OF SITE CHARACTERISTICS 5-1
5.1 CONTAMINANTS IN WATSON CREEK 5-1
5.1.1 Phase I Sediment Sampling 5-1
5.1.2 Phase II Sediment Sampling - 5-1
5.1.3 Phase III Sediment Sampling 5-4
5.2 POTENTIAL ROUTES OF CONTAMINANT MIGRATION AND
ROUTES OF EXPOSURE 5-4
5.3 "SITE-SPECIFIC FACTORS THAT MAY AFFECT REMEDIAL ACTIONS
ATTHESITE 5-5
6.0 SUMMARY OF SITE RISKS 6-1
7.0 DESCRIPTION OF ALTERNATIVES 7-1
7.1 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS 7-1
7.2 ALTERNATIVE A: NO ACTION 7-1
7.3 ALTERNATIVE B: LIMITED ACTION 7-1
7.4 ALTERNATIVE C: FULL-SCALE DREDGING/SOLIDIFICATION/LANDFILL 7-2
7.5 ALTERNATIVE D: 'HOT SPOT" REMOVAL/SOLIDIFICATION/LANDFILL 7-3
7.6 ALTERNATIVE E: AQUATIC PHYTOREMEDIATION 7-4
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Table of Contents
(Continued)
8.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 8-1
8.1 NINE EVALUATION CRITERIA 8-1
8.2 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT 8-2
8.3 COMPLIANCE WITH ARARS 8-3
8.4 LONG-TERM EFFECTIVENESS AND PERMANENCE 8-3
8.5 REDUCTION OF TOXICITY, MOBILITY, OR VOLUME THROUGH TREATMENT 8-4
8.6 SHORT-TERM EFFECTIVENESS 8-4
8.7 IMPLEMENTABILITY 8-5
8.8 COST 8-5
8.9 STATE ACCEPTANCE 8-5
8.10 COMMUNITY ACCEPTANCE 8-7
8.11 SUMMARY OF DETAILED EVALUATION 8-7
9.0 SELECTED REMEDY 9-1
9.1 BASIS FOR SELECTION 9-2
9.2 COST OF SELECTED REMEDY. 9-2
10.0 STATUTORY DETERMINATIONS 10-1
10.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT 10-1
10.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND
APPROPRIATE REQUIREMENTS 10-1
10.3 COST-EFFECTIVENESS 10-1
10.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE
TREATMENT TECHNOLOGIES (OR RESOURCE RECOVERY
TECHNOLOGIES) TO THE MAXIMUM EXTENT PRACTICABLE (MEP) 10-1
10.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT 10-1
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES 11-1
12.0 REFERENCES 12-1
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LIST OP APPENDICES
Appendix Pago
A RESPONSIVENESS SUMMARY A-1
LIST OF FIGURES
Figure Page
1-1 Location of Watson Creek 1-2
1-2 Location of 0-Field Disposal Sites 1-3
5-1 Watson Creek Sediment Sampling Locations 5-3
LIST OF TABLES
Table - ^J p*9*
5-1 Summary of Chemicals Detected in Watson Creek Sediment, O-RekJ Area, 1993 -1996 5-2
6-1 Chemicals of Potential Concern 6-2
8-1 Comparison of Costs for Watson Creek Remedial Alternatives 8-6
9-1 Summary of Costs for the Selected Remedy 9*3
10-1 ARARs For the Selected Remedy 10-2
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LIST OF ACRONYMS AND ABBREVIATIONS
2.4.6-TNT......... 2,4,6-trinitrotoluene
4,4-DDE 4,4-dichlorodiphenyldichloroethylene
APG Aberdeen Proving Ground
ARAR Applicable or Relevant and Appropriate Requirement
AVS Acid Volatile Sulfide
AWQC Ambient Water Quality Criteria
BTAG Biological Technical Advisory Group
BZ 3-quinuclidinyl benzilate
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act of 1980
CFR Code of Federal Regulations
CG phosgene
CN chloroacetophenone
CNS chloroacetophenone in chloroform
CS ortho-chlorobenzylidenemalonitrile
CWM chemical warfare materiel
OANC Decontaminating Agent Non-Corrosive
DM adamsite
DSHE Directorate of Safety, Health and Environment
EEQ Environmental Effects Quotient
ERA Ecological Risk Assessment
ER-L Effects Range Low
ER-M Effects Range Median
FFS Focused Feasibility Study
GAC granular-activated carbon
GB Sarin
GIS Geographical Information System
GWTF Groundwater Treatment Facility
H. azteca Hyalella azteca
ICF KE ICF Kaiser Engineers, Inc.
L Lewisite
LTC Lieutenant Colonel
MDE Maryland Department of the Environment
MEP Maximum Extent Practicable
ng/L micrograms per liter
NCP National Oil and Hazardous Substances Pollution Contingency Plan
NPL .National Priorities List
O&M Operation & Maintenance
OU Operable Unit
PCB polychlorinated biphenyl
PIU permeable infiltration unit
RA Risk Assessment
RI/FS Remedial Investigation/Feasibility Study
ROD Record of Decision
SARA Superfund Amendments and Reauthorization Act of 1986
SVOC semivolatile organic compound
TAL Target Analyte List
TCL Target Compound List
TCLP Toxicity Characteristic Leaching Procedure
TEU Technical Escort Unit
USAEC U.S. Army Environmental Center
USAEHA U.S. Army Environmental Hygiene Agency
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list of Acronyms and Abbreviations
(Continued)
USATHAMA ....U.S. Army Toxic and Hazardous Materials Agency
USCS Unified Soil Classification System
USEPA U.S. Environmental Protection Agency
USGS U.S. Geological Survey
UV/OX ;.... ultraviolet light catalyzed oxidation
UXO unexploded ordnance
VOC volatile organic compound
VX ethyl s-dimethyl amino ethyl methyl-phosphonothiohte
WP white phosphorus
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1.0 SITE NAME. LOCATION, AND DESCRIPTION |
The U.S. Army Aberdeen Proving Ground (APG) is a 72,516-acre (39.882-acre land area)
installation located ia southern Harford County and northeastern Baltimore County, Maryland, on the western
shore of the upper Chesapeake Bay (Rgure 1-1). The installation is bordered to the east and south by the
Chesapeake Bay; to the west by Gunpowder Falls State Park, the Crane Power Plant and residential areas;
and to the north by the City of Aberdeen and the towns of Edgewood, Joppatowne, Magnolia, and Perryman.
APG is divided into two areas by the Bush River the Edgewood Area of APG lies to the west and the
Aberdeen Area lies to the east.
Watson Creek is a 60-acre estuarine water body, located in the O-Field Study Area on the
Gunpowder Neck peninsula in the Edgewood Area of APG. It is bordered on the south and west by O-Field.
on the north and east by M-Field, and discharges to the northwest into the Gunpowder River. The location of
Watson Creek is shown on Rgure 1-1. Watson Creek receives both surface water runoff and groundwater
discharge from O-Field. The Watson Creek watershed drains into the Gunpowder River, which in turn drains
into the Chesapeake Bay. Surface water exchange between Watson Creek and the Gunpowder River is
restricted to a narrow culvert under Watson Creek Road. This culvert restricts tidal flushing of the creek (U.S.
Army Environmental Hygiene Agency [USAEHAJ, 1977).
Watson Creek provides an aquatic habitat for a variety of freshwater and estuarine aquatic life.
Freshwater and estuarine fish that have been caught in Watson Creek include largemouth bass
(Micropterus salmoides), black crappie (Pomoxis nigromaculatus), carp (Cyprinus carpkj), white perch
(Morona americana), striped bass (Morone saxatilis), catfish (Ictalurus spp.), yellow perch (Perca
flavenscens), eels (Anguila rostrata), and Atlantic silverside (Menidia menidia) (ICF KE, 1995). Other fish
species that may be present year round or seasonally in Watson Creek include various species of herring
(Alosa spp., Anchoa mitchilli, Brevoortia tyrannus), black drum (Pogonias cromis). bluefish (Pomatomus
saltatrix). croaker (Micropogonias undulatus), and mummichog (Fundulus heteroclitis). Invertebrates
identified in Watson Creek sediments include polychaetes, isopods, amphipods, and chironomids.
Sediment-dwelling organisms in Watson Creek are representative of typical tidal fresh water to low
mesohaline (Holland et al. 1989), including worms, amphipods, and isopods. Various factors such as
seasonal temperature fluctuations, restricted tidal flushing, high organic loading, and salinity (ranging from
0.5 to 10 parts per trillion) may have an impact on the abundance of organisms in Watson Creek. In
addition, the dams at Watson Creek which were constructed to enlarge the water surface area for wildlife
have "altered the natural habitat, greatly reducing the innate ability of the creek-estuary systems to
maintain conditions favorable for a balanced and health ecosystem..." (USAEHA. 1977).
The topography of the area surrounding Watson Creek is generally flat, with land-surface elevations
ranging from sea level to approximately 19 feet above mean sea level. Marshy areas surround Watson
Creek on all sides and are especially prevalent in the area immediately south of Watson Creek. Marshes
within this area are characteristically dense and are largely covered by Phragmites, a reed-like plant which
produces a very dense root mat
The O-Field area contains two (2) identified disposal areas and one (1) suspected disposal area
(Figure 1 -2). The northern disposal area, designated as Old O-Field, is a strictly controlled, contaminated
area. Contamination at Old O-Field is currently being remediated by the Groundwater Treatment Facility
(GWTF) and Permeable Infiltration Unit (PIU) interim actions. Further restrictions to on-site access are
currently being implemented. Old O-Reld is located adjacent to Watson Creek and east of Watson Creek
Road. The second identified disposal area. New O-Reld. is located south of Old O-Field and east of Watson
Creek Road. New O-Reld was used from 1950 to the late 1970s as a destruction, disposal, and training area.
The suspected disposal area, known as the 'Pit Site,* is on the west side of Watson Creek Road near the
Gunpowder River. Old O-Reld and the Pit Site were reportedly used from the late 1930s to mid-1950s as
disposal areas.
The residential areas closest to Old O-RekJ He approximately 2.7 miles north (on-post military
housing within the Edgeweod Area of APG). 3 miles to the west (Graces Quarters, Maryland), and 4.5 miles
to the north-northwest (Edgewood, Maryland, and Joppatowne, Maryland). In addition, Kent County.
Maryland, lies 6 miles east of Old O-Field.
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S*cfloni.o
Site Nam«. Location, and D«acripBon
PENNSYLVANIA
39*25'
39*20' -
MARYLAND
Baltimore
Washington Q
VIRGINIA
I /PROVING (AGROUND
/ /
re'is*
SOURCE: USGS. 1991
0123 KILOMETcRS
US ARMY
ENVIRONMENTAL CENTER
COKTMCT NO. 0*AAI»-tI-0-0014
• ICF KAISER
(4I«)
MR ll-«-M
WCLOC
1-1
LOCATION Or
WATSON CREEK
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S«ction 1.0
Site Nam*. Location, and Description
GUNPOWDER
RIVER
600
fEET
US ARMY
ENVIRONMENTAL CENTER
tannug m. »«*Ait-«i-»-aai4
• KF KAISER <
(•'•I «1!
».!*.«?
P1GURK 1-J
•••••••••
LOCATOH Of
0-ntLD DISPOSAL
srrts
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2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
APG was established in 1917 as the Ordnance Proving Ground and was designated a formal military
post in 1919. Testing of ammunition and other equipment and operation of training schools began at APG in
1918. Between this time and the onset of World War II, activities at APG included research and development
and large-scale testing of a .wide variety of munitions, weapons, and other equipment. Immediately prior to
and during World War- II, the pace of testing increased greatly. During the war. personnel strength at APG
exceeded 30,000. Similar but smaller-scale increases in development and testing activities were experienced
during the Korean and Vietnam conflicts.
APG's primary mission continues to be the testing and development of weapons, munitions,
vehicles, and a wide variety of support equipment. Chemical warfare research, development, and related
activities have occurred within the Edgewood Area. Specific activities at Edgewood have included laboratory
research, field testing of chemical munitions, pilot-scale manufacturing, and production-scale chemical agent
manufacturing.
Many areas of the Gunpowder Neck of the Edgewood Area have been used as impact areas for the
testing of ordinance; as such, there is the potential for encountering unexptoded ordnance (UXO) and/or
intact or leaking liquid-filled rounds which remain from testing. Disposal and testing activities have also taken
place in areas along the Gunpowder Neck. O-Field and J-FiekJ were the major disposal areas (the disposal
history of O-Field is discussed in more detail below). Currently, testing of combat tracked vehicles occurs at
H-Reld (to the south of O-Field) and testing of obscurants (e.g., smoke screens) takes place at M-FiekJ
(immediately northeast of Watson Creek).
2.1 HISTORY OF OLD O-FIELD
Periodic disposal of waste materials at the O-Field area began before World War II; the first
documented use of Old O-Field occurred in May 1941 (Yon et al., 1978), although other records suggest that
disposal activities occurred as early as the late 1930s. Disposal consisted of placing materials in excavated
trenches and then covering the trenches with soil Records indicate that some of the burial trenches were
100 yards long, 10 feet deep, and 10 feet wide; however, most known trenches are much shorter. The
existence of 35 trenches is documented in historical records (Yon et al., 1978). However, inspection of survey
notes and historical aerial photographs reveals that the trenches and pits are not distinct As disposal
activities continued, trenches were created which appear to overlay and intersect other trenches. Because of
this, the total number of trenches and their locations are not known. The last pit used for disposal of materials
within Old O-Field was closed in June 1953.
During the period of 1941 to 1949, tons of chemicaJ-filled/explosive-loaded munitions, contaminated
plant equipment, pipes, and tanks were buried or placed on the ground surface in the area of Old O-Field.
Interviewed personnel stated that the area contained 55-galton drums of mustard and lewisite (L); items filled
with chloroacetophenone (CN), chloroacetophenone in chloroform (CNS), and adamsrte (DM); munitions
containing explosive charges: and munitions filled with white phosphorus (WP) and other chemical warfare
materiel (CWM).
During August 1946, the unloading and decontamination operations of the SS Francis L Lee, a
Liberty ship containing mustard-filled German munitions captured during World War II, were conducted at
Edgewood Arsenal. The ship was anchored in the eastern channel of the Chesapeake Bay between Worton
Point and Stoops Point. The material was then loaded onto barges and towed up the Bush River to the
Edgewood dock. Contaminated empty German bombs (formerly mustard-filled), contaminated wood, and
dunnage were placed at Old O-Field for disposal.
In June 1949, a spontaneous ignition occurred in one of the disposal pits at Old O-Field where a
large variety of chemical-filled/explosive-loaded munitions had been buried. As a result of this explosion, a
broad area was contaminated with CWM, and unexptoded ordnance was dispersed around the area.
Immediately after this incident, an inspection was conducted by the Armed Services Explosive Safety Board.
A directive was issued calling for a thorough cleanup of the contaminated area. In November 1949, the
DAAA15-91-0-OOH £l " necori of Decision
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Section 2.0
Site History and Enforcement Activities
responsibility for the disposal and cleanup operations at Old O-Field was given to the Command of the
Technical Escort Detachment at Edgewood Arsenal.
2.2 CLEANUP ACTIVITIES AT OLD O-FIELD
2.2.1 LTC Dean Dickey's Affidavit
The main source of information concerning early cleanup activities at Old O-Field is a testimonial
prepared by Lieutenant Colonel (LTC) Dean Dickey (Yon et al., 1978), who was Offtoer-ln-Charge of cleanup
at Old 0-Fieid. and who later returned to the Edgewood Area as Commander of the U.S. Army Technical
Escort Unit (TEU).
Between September 1949, and the early 1950s, LTC Dickey's team performed a surface sweep and
clearance of Old O-Field. The following activities were performed:
Fuzes, bursters, and boosters were gathered, placed in drums, and detonated. The handling
of items and drums in Old O-Field was slowed down by the quantity of WP in the ground,
which ignites and bums when exposed to air.
Several hundred drums, mustard-filled rounds (including German mustard-filled 250-kg and
500-kg rounds), and tear gas-filled rounds were recovered from the surface of Old O-Field.
The mustard-filled rounds and WP rounds were destroyed by placing them in a pit-with
lumber and napalm and burning.
Old O-Field was also used for the destruction of leaking mustard and lewisite one-ton
containers. The agent was destroyed by pouring it into flat steel pans and igniting it in the
presence of lime.
During the recovery activities, the surface of Old O-Field was decontaminated by pouring
Decontaminating Agent Non-Corrosiv* (DANC, which contains approximately 95% 1,1,2,2-
tetrachloroethane) and lime (calcium hydroxide) on the field. Approximately 1,000 barrels of
DANC were used. Contaminated soil was then scooped up and put on top of Old O-Field.
The trees were decontaminated by placing 2,4,6-trinitrotoluene (2,4,6-TNT) under cans of
lime and detonating the cans to spread the lime. The reaction of lime with the agent in the
trees caused the leaves and trees to ignite and bum.
The Old O-FiekJ pits and their contents were then burned. Hundreds of gallons of fuel oil
were pumped into the pits. The entire field was then sprayed with fuel oil. Time fuzes were
placed in the pits. The pits and the entire area burned for two days, and numerous
explosions occurred. The date for this phase of the cleanup is not given, but is presumed to
.have occurred during the early 1950s.
During these cleanup activities, a number of unplanned detonations occurred. These
explosions resulted in the release of mustard to the surface of Old O-Field and the
surrounding trees and surface water bodies.
Other portions of LTC Dickeys affidavit indicate that, although a large quantity of disposed materials
have been recovered from the surface of Old O-Field and some of the pits, a much larger quantity of
munitions, bulk containers, and other items remain buried at the site.
2.2.2 U.S. Army TEU Surface Sweeps of Old O-Field
From the late 1960s to the early 1970s, the U.S. Army TEU performed surface sweeps of the area, A
number of suspect CWM-filled rounds were recovered from Old O-Field, temporarily stored in Conex
containers at Old O-Field, and then transported and stored in the storage bunkers at N-Fiekj.
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Section 2.0
Site History and Enforcement Activities
2.3 HISTORY OF NEW 0-FIELD
Records indicate that in December 1950, the survey and layout of the second disposal area within
the boundary of the-O-Field area was accomplished. This area is south of Old O-Field and east of Watson
Creek Road, and is defined as the New O-Field disposal area. Yon and others (1978) reported that 9 pits at
New O-Field were used for disposal operations from 1950 to 1961. The disposed material is reported to have
included explosives; acids; animal carcasses; research laboratory samples of ethyl s-dimethyt amino ethyl
methyi-phophonothiolate (VX), Sarin (GB), and impregnate; mustard and WP-filled shells; ortho-
chlorobenzylidenemalonitrile (CS), DM, and CN. The pits were 20 feet wide and ranged in length from 40 to
100 feet. The depth of the pits is not known, but is probably similar to the depth of pits at Old O-Field
(maximum depth of at least 12 feet) (U.S. Geological Survey [USGS], 1991). In later years, until disposal
ended in the late 1970s, the primary activity at New O-Field was destruction of materials by burning (USGS,
1991). This most likely included burning of wastes containing chlorinated solvents (Nemeth, 1989).
An accidental ignition of one disposal pit was reported in New O-Field in August 1961. The report
describing this incident states that the pit contained 55-gallon drums of acid on dunnage; one 300-gallon tank
contaminated with mustard; laboratory samples and waste material consisting of VX, GB, phosgene (CG).
and numerous bottles of miscellaneous laboratory chemicals; GB-contaminated pipe: and 3-quinuclidinyi
benzilate (BZ) contaminated rags. The ignition of the pit was reported as being caused by an unknown
laboratory chemical after a brief but heavy rain shower.
2.4 PREVIOUS INVESTIGATIONS
This section summarizes the results of past environmental studies focusing on Watson Creek.
2.4.1 Environmental Survey
An Environmental Survey of the Edgewood Area of APG was conducted in 1977 and 1978 by the
U.S. Army Toxic and Hazardous Materials Agency (USATHAMA), now known as the U.S. Army
Environmental Center (USAEC) (Nemeth et al., 1983), to determine if chemical contamination from past
operations was presenting a hazard to the off-post environment The survey indicated that groundwater
flowed from Old O-Field to Watson Creek, although some component flowed toward the Gunpowder River.
Results of the study also indicated that the groundwater at Old O-Rekj contained metals, volatile organic
compounds (VOCs), semrvoiatile organic compounds (SVOCs), and CWM degradation products at
concentrations above 1,000 |ig/L (micrograms per liter). Surface water in Watson Creek was found to
contain low levels of VOCs and arsenic; however, none of the compounds were detected above their
respective surface water criteria. Finally, the report concluded that because VOCs volatilize from surface
water after discharge to Watson Creek, and because Watson Creek is diluted upon entry into the Gunpowder
River, significant degradation of surface water quality within the Gunpowder River was not occurring.
2.4.2 Surface Water Quality Survey
USAEHA conducted a surface water quality and biological study of Watson Creek and nearby
creeks (USAEHA. 1977). Due to poor tidal flushing in Watson Creek, unusually high loading of metals was
detected in the sediment The report indicated elevated concentrations of cadmium (0.73 to 1.01 mg/kg).
copper (20 to 41.4 mg/kg). and zinc (29 to 167 mg/kg): and low concentrations of arsenic (9.5 mg/kg) in the
sediment. Silver concentrations (0.023 to 0.042 mg/l) in the surface water at Watson Creek exceeded the
recommended safe limit of 0.02 mg/l, outlined in Water Quality Criteria (National Academy of Sciences,
1972). Bioassays that were conducted using sediment samples determined that the contamination in the
sediment was at levels non-lethal to aquatic inhabitants.
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Section 2.0
Site History and Enforcement Activities
2.4.3 Hydrogeologic Investigation
In 1984, the USGS began a study to investigate the source, extent, and possible migration of
contaminants from the Old O-Field site. The final report by Vroblesky et al. (USGS, 1991) presents a
preliminary characterization of the contamination of the groundwater, surface water, and bottom sediment in
the O-Field area of APG, and describes the probable hydrologic and chemical effects of relevant remedial
actions on the groundwater at the site. Sampling in August 1985 revealed maximum detected concentrations
of the following metals in surface water arsenic (1.26 mg/L); cadmium (0.019 mg/L): copper (2.5 x 10'3
mg/L); and mercury (3.8 x 10"4 mg/L). Sediment sampling in November 1984 and August 1985 also
identified the following maximum detected concentrations: arsenic (30.6 mg/kg); chromium (39.4 mg/kg);
copper (66.7 mg/kg); lead (47.9 mg/kg); mercury (0.99 mg/kg); zinc (394 mg/kg); phenanthrene (65.1 jig/kg);
1,2-dichloroethene (0.2 jig/kg); and trichlorofluoromethane (98 jig/kg) (USGS, 1991).
2.4.4 Groundwater and Surface Water S' Tipllng, Fall 1991
In November 1991, the Army colle d groundwater samples from all existing monitoring w>
Surface water samples were also collected from Watson Creek and the Gunpowder River. The re
concluded that VOCs, SVOCs, polychlorinated biphenyls (PCBs), herbicides, pesticides, and explo
compounds were not detected in surface water samples collected from Watson Creek an>
Gunpowder River adjacent to O-Field; however, oxathiane (a CWM degradation product) was detecto . ..i
one sample collected from Watson Creek east of Old O-Field (at 7.8 ng/L).
2.4.5 Old O-FIeld Groundwater Treatment Remedy
A Focused Feasibility Study (FFS) was performed to evaluate remedial alternatives for the
groundwater, OU1, at Old O-Field (ICF Kaiser Engineers, Inc. (ICF KE], 1990). As part of this study, aquifer
tests were performed to aid in designing a groundwater extraction system (ICF KE. 1991 a). Treatability tests
were conducted to evaluate the implementability of various groundwater treatment technologies. A number of
promising technologies were tested at both the bench- and pilot-scale.
The data obtained from the treatability tests were used to select a preferred remedial technology.
Groundwater extraction and treatment using chemical precipitation for removal of the inorganic ana! $
followed by ultraviolet light catalyzed oxidation (UV/OX) for removal of the organic contaminants was seie- '
as the proposed remedial treatment technology (ICF KE. 1991b). Discharge of treated groundwater to : •
Gunpowder River was also proposed. Based on the results of the FFS, the aquifer tests, and the treatability
studies, a Proposed Plan was developed which addressed groundwater extraction and treatment for the Old
O-Field Area (U.S. Department of the Army, 1991 a). A ROD which documented the remedy selection was
signed by the Army and the U.S. Environmental Protection Agency (USEPA) Region III in September 1991
(U.S. Department of the Army, I991b).
ICF KE then developed the conceptual design for the groundwater extraction, treatment, and
discharge system (ICF KE. 1991c). The system was designed to intercept and treat the contaminated
groundwater emanating from Old O-Field and to prevent loading of contaminants into Watson Creek. Under
a separate contract, Roy F. Weston, Inc. completed the engineering design and construction of the GWTF.
In addition to the core processes of chemical precipitation and UV-OX specified in the ROD, air stripping and
granular-activated carbon (GAC) adsorption were added to the final design. The GWTF began operation in
April 1995.
2.4.6 Old O-Field Source Area Treatment Remedy
A FFS was performed by ICF KE to evaluate removal alternatives for the source area at Old O-
Field, OU2 (ICF KE, 1994). As part of this study, a hazar assessment was performed to evaluate the
hazards associated with explosions and dispersion of chemical agents within Old O-Field. Based on the
results of the hazard assessment and the FFS, a Proposed Plan was developed by ICF KE which addressed
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Section 2.0
Site History and Enforcement Activities
the source area at Old O-Field (U.S. Department of the Army, 1994a). Under this plan, a PIU, consisting of a
layer of sand and other granular materials, was proposed for the surface of Old O-Field. The PIU was
designed to: 1) reduce the threat of a release of chemical agents by covering the site with non-flammable
materials, which wilTserve to cut off the air flow to the surface of Old O-Field, stop erosion, and stabilize the
soil; 2) provide a blast resistant layer on top of the ordnance within Old O-Field; and 3) provide a vapor
barrier to reduce the emission of chemical agents from an underground release. Additionally, covering the
surface of Old O-Field will stop surface runoff from migrating off site to nearby surface water bodies (e.g.,
Watson Creek and the Gunpowder River).
Once the PIU is constructed and operating, treatability studies will be performed to evaluate the
feasibility of applying solutions through the PIU to enhance leaching of contaminants from the soil. The ability
of the groundwater extraction and treatment system to capture and treat the contaminated groundwater
emanating from Old O-Field and solutions applied to Old O-Field will be verified.
An interim ROD, which documents the remedy selection, was signed by the Army and USEPA
Region III in October 1994 (U.S. Department of the Army, 1994b). ICF KE then developed the design for the
PIU (U.S. Department of the Army, 1995). Under a separate contract, Roy F. Weston. Inc. has initiated
construction of the PIU. Completion is anticipated by early 1998.
2.4.7 O-Field Area Remedial Investigation/Feasibility Study
The Army performed a Remedial Investigation/Feasibility Study (RI/FS) of the entire O-Field study
area. The Rl consisted of the installation of monitoring wells and the collection and analysis of samples-from
surface water, sediment, groundwater, air, and soil. Extensive soil gas surveys and geophysical surveys were
also performed.
Because the toxicity of the military-specific compounds is not well 'known, toxicrty tests were
conducted to evaluate potential impacts to aquatic life. Macroinvertebrates were collected in sediments from
Watson Creek and the Gunpowder River and analyzed to evaluate the potential for bioaccumulatkm of
contaminants. Further hydrogeologic investigation of the area has been performed through aquifer testing
and groundwater flow modeling. Results of this investigation are presented in the Rl Report (ICF KE, 1995).
2.4.8 Watson Creek Sampling
Watson Creek sediment sampling events were conducted in September 1993 (Phase I), March 1995
(Phase II), and June 1996 (Phase III). Phases I and II were conducted during the Rl, and the results are
presented in the Rl Report (ICF KE. 1995). Data from the three phases of sampling indicate that humans
and aquatic life would not be adversely impacted by chemicals in the surface water in Watson Creek;
however, benthic-dwelling species may be impacted by the metals concentrations in sediment in Watson
Creek. Results from Phases I, II, and III are discussed in the FFS for Watson Creek (ICF KE, 1997a).
2.4.9 Focused Feasibility Study for Watson Creak
The FFS for Watson Creek evaluated the risks posed by the sediment in Watson Creek and the
potentially applicable remedial technologies for mitigating these risks (ICF KE. 1997a). The Proposed Plan
for Watson Creek (ICF KE, 1997b) and this ROD are based on the results of the FFS report
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3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION |
The FFS Report and Proposed Plan for OU3 were released to the public in July 1997. Both of these
documents are available in the Administrative Record and the information repositories maintained at the
Harford County Library • Aberdeen Branch, Aberdeen, MD; Harford County Library - Edgewood Branch,
Edgewood, MO; and Washington College - Miller Library, Chestertown, MO. The notice of availability of these
documents was published in the Aegis (Harford County), the Baltimore Sun, the Avenue (Baltimore County),
and the Kent County News on July 2,1997.
The 45-day comment period was held from July 2, 1997 through August 15, 1997. In addition, a
public meeting was held on July 28, 1997. At this meeting, representatives from APG, USEPA, and MOE
presented a summary of the site conditions and remedial alternatives under consideration. A response to the
comments received during this period is included in the Responsiveness Summary, which is part of this
ROD.
This decision document presents the selected remedial action for Watson Creek, OU3 of the Old O-
Field Study Area, APG, Maryland. The remedy has been chosen in accordance with CERCLA, as amended
by SARA, and, to the extent practicable, the NCP. In addition, this decision incorporates the findings of the
FFS, which evaluated the remedial alternatives for OU3. The decision for this OU is based on data contained
in documents found in the Administrative Record.
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4.0 SCOPE AND ROLE OF OPERABLE UNIT OR RESPONSE ACTION |
Past disposal operations at the 0-Field area have led to contaminated soil and groundwater at and
near O-Field. The &my has decided to manage the environmental contamination in the different media at the
O-Field area in a phased approach. This separation of environmental media into OUs allows the Army to
begin remediation prior to full assessment of the O-Field Area. The NCR provides that CERCLA National
Priorities List (NPL) sites 'should generally be remediated in OUs when earty actions are necessary or
appropriate to achieve significant risk reduction quickly, when phased analysis or response is necessary or
appropriate given the site or complexity of the site, or to expedite the completion of a total cleanup* (40 CFR
300.430(a)(l)(ii)(A)). The Army's phased approach to O-Field is consistent with these objectives.
An OU is defined by the NCP as a discrete action which is an incremental step toward comprehen-
sively mitigating site problems. The OUs for the O-Field area at APG have been defined as follows:
OU1: Contaminated groundwater beneath and immediately downgradient of the Old O-Field
disposal trenches which has been contaminated from past disposal practices;
OU2: Contaminant source area within the disposal trenches at Old O-Field;
OU3: Contaminated sediment and surface water within Watson Creek; and
OU4: Contaminated soil and groundwater at New O-Field.
The Army has already selected remedies for OU1 and OU2, as discussed in Sections 2.4.5 and
2.4.6. respectively, of this ROD. OU4 requires additional investigation and will be handled in a separate
action.
As mentioned in Section 1.0, Watson Creek (OU3) receives both surface water runoff and
groundwater from O-Field (which includes OU1, OU2, and OU4). This remedy for OU3 addresses the
potential adverse effects to benthic communities due to elevated concentrations of inorganics and 4.4-
dichlorodiphenyldichloroethvlene (4,4-OOE) in the Watson Creek sediment. This action will be consistent with
planned future activities, to the maximum extent practicable. In addition, the remedy for OU3 will be taken
into consideration during remedy selection for OU4.
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5.0 SUMMARY OF SITE CHARACTERISTICS
This section provides a summary of the nature and extent of contamination in Watson Creek.
5.1 CONTAMINANTS IN WATSON CREEK
Watson Creek sediments were sampled in 1964 and 1985 by the USGS (USGS, 1991). Sample
analyses revealed detectable, and in some cases elevated (as compared to sediment screening values),
levels of heavy metals, including arsenic, lead, and mercury (Section 2.4.3). Detectable levels of some
organic compounds were also found. The data indicated that additional sampling of sediment was needed to
evaluate temporal changes and to complete the data set to allow an Ecological Risk Assessment (ERA) to be
performed.
The Phase I sediment sampling locations were based on sample locations used during the
1984/1985 Watson Creek sediment sampling (USGS, 1991). Based on the Phase I bioassay results, Phase
II sampling locations were chosen to further characterize the impact of metals on the benthic communities in
Watson Creek. Phase III sample locations were selected to delineate areas which might be considered 'hot
spots' within Watson Creek. Sediment bioassays were collected throughout Watson Creek to determine if
benthic communities were being .impacted. Samples were collected and analyzed for VOCs, SVOCs,
pesticides/polychlorinated biphenyls (PCBs), and CWM degradation products to evaluate the presence of
these chemicals in sediment in Watson Creek. A summary of the chemicals detected in the Watson Creek
sediment is presented in Table 5-1.
5.1.1 Phase I Sediment Sampling
Phase I sampling activities occurred in October 1992 and September 1993. Background sediment
samples (DC8-1, PCB-1. and SCB-1) were collected from Dundee Creek and'Saltpeter Creek in October
1992. Phase I sediment samples (WC-1 through WC-12) were collected from Watson Creek in September
1993 (Rgure 5-1). All of the Phase I sediment samples were analyzed for metals, total phosphorus, Target
Compound List (TCL) VOCs, CWM degradation products and explosives compounds, ammonia, acid volatile
sulfide (AVS), grain-size distribution, and Unified Soil Classification System (USCS) classification. Three
sediment samples (WC-1, WC-4. WC-6) were also analyzed for SVOCs, dioxins, and furans. In addition to
the chemical and physical analyses, bioassays were collected at each sampling location to determine the
impact of sediment contamination on benthic communities in Watson Creek.
Results from the Phase I sediment sampling event indicated that contaminants of potential concern
(those analytes which were detected above background levels) are metals. These metals include aluminum,
arsenic, barium, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, mercury,
silver, sodium, and zinc. TCL VOCs. SVOCs. CWM degradation products, and explosives compounds were
not detected in sediment or background samples. Bioassay results indicate that the survival of Hyalella
azteca (H. azteca) in sediment collected from WC-3 was significantly lower than in the remaining samples
and the controls*. Additionally, growth of H. azteca in sediment collected from WC-9 was inhibited when
compared to the remaining sediment samples and the controls.
5.1.2 Phasa II Sediment Sampling
The results of sediment bioassays and chemical analyses from the Phase I sediment sampling event
indicated the potential for limited impacts to benthic-dwelling aquatic species in Watson Creek due to the
elevated concentrations of metals in the sediments. Based on the Phase I bioassay results, impacts to
benthic communities were most likely to occur at Phase I sample locations WC-3 and WC-9. Therefore, a
total of 23 locations (WC-13 through WC-35) were sampled within Watson Creek in March 1995, to provide
additional data regarding metals concentrations (Rgure 5-1). Additionally, bioassay tests similar to those
performed during Phase I were also performed on the Phase II samples.
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Serton 5.0
Summary of Silt Cnaracterisacs
Table 5-1
Summary of Chemicals Detected In
Watson Creek Sediment, O-Field Area
1993-19961"
Chemical
Inorganics (mg/kg):
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
Silver
Sodium
Vanadium
Znc
Frequency of
Detection
85/85
85/85
85/85
33/85
29/85
• 85/35
85/85
84/85
80/85
85/85
85/85
85/85
85/85
72/85
85/85
85/85
42/65
13/85
85/85
85/85
80/85
Organic* dig/kg):
Acetone
Bis(2-ethylhexyl)Dhthaiate
2-Butanone
Diethyl phthalate
Methylene chloride
4.4-DDE
5/27
5/18
3/27
5/27
2/27
4/18
Range of Detected
On-Site
Concentrations0"
281 -22,000
0.467 - 82.5
1.05-111
0.451 -3.35
1.36-4.62
179-4,510
1.22-132
4.3-31.3
0.737-305
771 -41,200
1.05-109
132-5.970
10.3-637
0.23-5.91
1.49-42.7
79-2.190
0.97-3.66
0.14-7.34
573-11.110
0.906-43.5
16.2-1.130
140-1.500
770-4.100
17-57
71 -180
31 -100
20.7-34.5
Range of Detected
Background
Concentrations'6'
10,100 • 16.300
4.8-7.1
50.8 - 74.3
2.4
NO
1.590-3.070
29.2 - 35.2
21.8-28.4
67.8 - 80.2
28.000-32.000
59.8-91.4
3,780-5.480
• 231 -367
NO
42.3-49.1
1.730-2,230
1.2-3.2
ND
4.210-8,190
41.7-58.8
283-410
ND
ND
ND
ND
ND
ND
CWM Degradation Products (mg/kg):
1.4-Oithiane
1/17
21,000
ND
Notes:
ND » Not Detected
w Chemicals not detected substantially above the levels reported in laboratory or field blanks (validated
as 'B'} were excluded from this summary.
w Summaiy of all three sediment sampling events at Watson Creek: Phase I-September 1993;
Phase II • March 1995; and Phase III -June 1996.
"' Background samples were collected from Dundee Creek and Saltpeter Creek in October 1992.
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Section 5.0
Summary of Site Characteristics
Results from Phase II sediment sampling confirmed that contaminants of potential concern (those
analytes which were detected up to nine times the background levels) are metals. These metals included
aluminum, arsenic^ cadmium, chromium, cobalt, copper, iron, manganese, mercury, selenium, and zinc.
Although arsenic and mercury were detected above background levels throughout Watson Creek, the
remaining metals were detected in localized areas. Bioassay results from Phase II sampling indicate that the
survival of H. azteca in sediment collected from two samples were significantly lower than in the remaining
samples and the controls. However, there did not appear to be any correlation between the bioassay and
chemical results from either the Phase I or Phase II Watson Creek sediment samples.
5.1.3 Phase III Sediment Sampling
Phase III sampling was conducted in June 1996 to further characterize the extent of contamination in
Watson Creek sediment and to evaluate the potential impact of contaminated sediment on benthic
organisms in the creek from the presence of metals or other compounds (e.g., organics) which were not
identified in previous investigations. The first objective was met by collecting additional sediment, subsurface
soil, and groundwater samples in and along the border of Watson Creek. The second objective was met by
performing sediment bioassays to evaluate sediment toxicity. Results of the Phase III sediment sampling
event were used to revise the Watson Creek sediment ERA.
The sediment sampling locations were chosen to delineate 'hot spots,' which were defined by: 1)
locations where elevated chemical concentrations in sediment; 2) toxicity based on the results of sediment
bioassay tests; and 3) a combination of both elevated chemical concentrations in sediment and toxicity
based on the results of the sediment bioassays. Four sample areas were chosen for the Phase III sampling
event: Area 1 (grid sampling at G-1 through G-37 and WC-3); Area 2 (WC-9, WC-27. WC-28, and WC-44);
Area 3 (WC-36 through WC-40); and Area 4 (WC-41 through WC-43). The sediment sampling locations are
shown on Figure 5-1.
All 50 of the Phase III sediment samples were analyzed for Target Anafyte List (TAL) metals and
physical analysis. Fifteen samples were analyzed for TCL VOCs, SVOCs, pesticides/PCBs; and five samples
were analyzed for CWM degradation products. In addition to collecting sediment samples for chemical
analysis during Phase III, 13 samples were collected for H. azteca bioassays.
Results from the Phase III sediment sampling event confirmed the presence of elevated metals in
Watson Creek. These metals included aluminum, arsenic, barium, beryllium, cadmium, calcium, chromium,
copper, iron, lead, manganese, mercury, silver, and zinc. Arsenic, copper, mercury, and zinc were detected
above background in all areas of Watson Creek. The remaining metals were detected above background in
localized areas of Watson Creek.
in addition to the elevated metals, a few VOCs and SVOCs were detected in Watson Creek
sediment. Acetone, 2-butanone, and methylene chloride were detected in localized regions of Areas 1 and 3
sediment. Bis(2-ethylhexyl) phthalate and diethyl phthalate were detected in scattered locations throughout
Watson Creek. Many of the detected VOCs and SVOCs are used as common laboratory solvents; therefore.
it is highly probable that the detections are the result of contamination during analysis. The pesticide
degradation product 4,4-DDE was detected in localized areas of the southern region of Watson Creek
(WC-39, WC-41, and WC-43). Based on the locations where 4,4-OOE was detected, the concentrations are
most likely due to contamination from New O-Field. Pesticides have been detected in New O-Field marsh
samples collected in the vicinity of Watson Creek. 1,4-Dithiane was detected in WC-3 downgradient of Old
O-Field, but not in the duplicate sample for that location. Bioassay results from Phase III sampling indicated
there were no statistically significant differences in the survival and growth of H. azteca between the sediment
samples collected from Watson Creek and the control sample.
5.2 POTENTIAL ROUTES OF CONTAMINANT MIGRATION AND ROUTES OF EXPOSURE
The Risk Assessment (RA) prepared as part of the Rl for the O-Field Area indicated that no
complete pathways exist by which humans could be exposed to chemicals in the surface water or sediment
of Watson Creek under current or future land-use scenarios. Furthermore, the results of surface water
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Section 5.0
Summary of Site Characteristics
analysis indicated that aquatic life would not be adversely affected by chemicals in surface water. Based on
discussions with the USEPA Region III Biological Technical Advisory Group (STAG), the evaluation of
potential adverse effects to aquatic life from the presence of chemicals in sediment was identified as the
most viable potential exposure pathway and was selected for evaluation in the ERA. Results of the ERA are
discussed in Section 6.0 of this ROD.
5.3 SITE-SPECIFIC FACTORS THAT MAY AFFECT REMEDIAL ACTIONS AT THE SITE
Although there is no risk of human exposure to chemicals in the sediment at Watson Creek, there is
potential risk to human health due to the possible presence of ordnance in Watson Creek. Many areas within
the Gunpowder Neck peninsula were at one time used as impact areas for the testing of ordnance. In
addition, there is the likelihood that ordnance was ejected into Watson Creek from Old O-Field during
explosions in the late 1940s. For these reasons, the Army believes it is likely that ordnance is buried within
the Watson Creek sediment The presence of ordnance may limit the activities that are considered safe to
perform at Watson Creek.
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16.0 SUMMARY OF SHE RISKS |
The Remedial Investigation for the 0-Field area evaluated the full range of potential human and
ecological receptorsnn Watson Creek. The results of this assessment indicated that there was no risk of
human exposure to chemicals in the surface water or sediment of Watson Creek under current or future
land-use scenarios. Furthermore, the results of surface water analysis indicated that aquatic life would not be
adversely affected by chemicals in surface water. Based on discussions with the USEPA Region III BTAG,
the potential adverse effects from the presence of chemicals in the Watson Creek sediment was identified as
the most likely potential exposure pathway to aquatic life and was selected for evaluation in the FFS ERA.
Risk estimates were developed using the results of the three phases of chemical and biological
analysis. The chemical analysis results for the sediment samples indicated that certain metals (specifically
arsenic, copper, mercury, silver, and zinc) and one pesticide degradation product (4,4-DDE) are present at
concentrations high enough to have the potential to cause limited adverse effects to sediment-dwelling
organisms (such as clams, crabs, tubeworms, etc.). However, the chemical data indicate that the
concentrations are just above the levels of concern, thus, any impacts that may occur are expected to be
small and would not threaten the overall health of the sediment-dwelling community (Table 6-1).
Sediment samples were also collected during the three phases for toxicity testing, which consisted of
the introduction of test aquatic species-into the sample for a period of time. The aquatic species used in
these toxicity tests are known to be sensitive to chemicals. During the tests, measurements of survival and
growth of the test aquatic species were made to assess the effect of chemicals within the sample on the
organism. . .
The results of the Phase III toxicity tests performed with Watson Creek sediment samples indicated
that adverse effects to sediment-dwelling organisms are unlikely at the sampled locations. The results of
Phase I and II toxicity tests were not taken into consideration, because low survival in the laboratory controls
invalidated the results. Although toxicity tests were only performed for 13 of the SO Phase III sediment
sampling locations, samples which were tested were taken from locations where survival was lowest during
the Phase I and II toxicity tests (e.g., WC-3, WC-27. and WC-28) and where the greatest chemical
concentrations were detected in the Phase III chemical analyses (e.g., WC-3). Because no reduction in
survival or growth of the test aquatic species occurred for these sample locations where adverse effects were
considered most likely, it is unlikely that a reduction in survival or growth would have occurred for the sample
locations which were not tested in Phase III. Thus, adverse effects to the overall health of the sediment-
dwelling community in Watson Creek are unlikely.
The risk assessment concludes that Watson Creek surface water does not pose a threat to human
health, terrestrial species, or aquatic species; therefore remediation of surface water is not needed. In
addition, the results of the sediment sampling indicate that there mavbe a small threat posed to sensitive
sediment-dwelling organisms by the metals detected in the sediment: however, the overall health of the
sediment-dwelling community does not appear to be threatened based on the Phase III toxicity test results.
The principal contaminant migration pathways from OW O-FieW to Watson Creek have been partially
mitigated by the OU1 action (interception of contaminated groundwater, treatment, and discharge into the
Gunpowder River which is already in the operational phase) and the OU2 action (construction of the PIU on
the Old O-FieW source area which is in the construction phase). Furthermore, gradual redistribution of the
fine-grained sediment particles is expected to occur naturally over time throughout the creek bed (due to
changes in water elevation, movement of fish and other organisms, etc.). In addition, other chemical and
physical processes, such as reduction, complexation, and ton exchange, may naturally tower the bioavailabte
metals concentrations in the sediment. It is therefore reasonable to expect that the concentrations of metals
within Watson Creek sediment will decrease over time, even in the absence of active remediation.
Although the toxicity tests from Phase III sampling indicate that metals in Watson Creek sediment
have no observed adverse effects on the health of the sediment-dwelling organisms, previous toxicity results
from Phase I & II sampling (since voided due to poor control group performance) prompted the Army to
examine the remedial alternatives that could be performed to reduce the concentrations of metals in Watson
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Section 6.0
Summary of Site RisXj
Table 6-1
Chemicals of Potential Concern
Chemical
Arsenic
Copper
Mercury
Silver
Zinc
4.4-DDE
Max. Detected
Concentration
(mg/kg)
82.5
305
5.91
7.34
1,130
0.0345
ER-L
(mg/kg)
8.2
34
0.15
1.0
150
0.0022
EEQ (L)
10.1
9.0
39.3
7.3
7.5
15.7
ER-M
(mg/kg)
70
270
0.71
3.7
410
0.027
EEQ (M)
1.2
1.1
8.3
2.0
2.8
1.3
Effects Range Low (ER-L): Approximate concentration of a given compound at which
effects are likely to occur in sensitive life stages and/or species.
Effects Range-Median (ER-M): .Approximate concentration of a given compound at which
effects are likely to occur in most species.
Environmental Effects Quotient (EEQ): Ratio of contaminant concentration to ER-L/ER-M
values.
EEQ<=1 Adverse effects considered unlikely
EEQ> 1 Potential for adverse effects to occur
EEQ>10 Moderately high potential risk
EEQ>100 Extreme risk
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Section 6.0
Summary of Site Risks
Creek sediment. The purpose of such a remedial action would be to lower the overall concentrations to a
level that is not expected to result in adverse impacts to sediment-dwelling organisms, or to remove the
shallow sediment aod replace it with clean material.
The remediation of sediment is often a difficult problem and can result in greater harm to the aquatic
and sediment-dwelling species than the risk originally posed by contaminants. Removal (dredging) of creek
sediments will invariably cause a substantial resuspension of fine-grain sediments into the water column.
Many metals are preferentially adsorbed to the finer-grained sediment components. As such, resuspending
the fine-grained sediment component during a remedial action may effectively remobilize the metals
contamination increasing the likelihood that aquatic species, and possibly terrestrial species, would be
exposed to the metals.
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7.0 DESCRIPTION OF ALTERNATIVES ~"~~~~ I
During the technology screening conducted as part of the FFS (ICF KE, 1997a). applicable remedial
technologies were Identified, evaluated, and assembled into remedial alternatives as follows:
No Action;
Limited Action;
Full-Scale Dredging/Solidification/Landfill;
"Hot Spot" Removal/Solidification/Landfill; and
Aquatic Phytoremediation.
This section describes the alternatives that were considered for remediating OU3.
7.1 APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
As required by the NCR, the selected alternative must be in compliance with all "applicable or
relevant and appropriate requirements" (ARARs). ARARs are the cleanup standards, standards of control,
and other substantive environmental requirements, criteria, or limitations promulgated under Federal or State
law that specifically address a hazardous substance, pollutant, contaminant remedial action, location, or
other circumstance of a Superfund site.'
Chemical-specific ARARs are not available for sediment; however, State surface water quality
standards and Federal Ambient Water Quality Criteria (AWQC) apply for surface water at Watson Creek.
Location-specific ARARs include Federal and State regulations protecting endangered or threatened species;
migratory birds; and bald and golden eagles. Action-specific ARARs relevant to Watson Creek indude
Federal and State regulations regarding hazardous wastes; environmental quality; floodplain management;
wetland protection; and storm water, erosion, and sediment control.
7.2 ALTERNATIVE A: NO ACTION
Under this alternative, no action would be taken to address the contaminated sediment at Watson
Creek. The No Action alternative is intended to serve as a baseline with which to compare the risk reduction
effectiveness of the other alternatives that are under consideration. Based on its location in the Edgewood
Area, access would remain restricted; however, no additional land-use restrictions would be imposed at
Watson Creek. Risks to benthic communities due to contaminants in the sediment would not be reduced or
controlled under the No Action alternative.
The No Action alternative would not involve active treatment or containment Therefore, there would
be no significant reduction in toxteity, mobility, or volume of contaminants in Watson Creek.
There would be no implementation time or cost associated with the No Action alternative because no
remedial activities would be implemented at the site.
7.3 ALTERNATIVES: LIMITED ACTION
The Limited Action alternative would include implementation of the following actions, which are
detailed further in Section 9.0:
Institutional controls;
Physical security measures;
Public education programs;
Long-term monitoring of site conditions; and
Five-year reviews.
The purpose of this alternative is to continue limiting access to the site, inform the public of site
hazards, provide a database of site conditions, and evaluate changes over time. Long-term environmental
monitoring of site conditions would consist of periodic sediment sampling and tissue sampling (if possible) of
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Section 7.0
Description of Alternatives
fish and/or invertebrates within Watson Creek. Site conditions would be reviewed at least every five years,
as required by the NCP for all sites where contaminants remain at or above levels that allow for unlimited use
and unrestricted exposure. This alternative does not use any technology that reduces the toxicity, mobility, or
volume of contaminants. Land use restrictions would be inputted into APG's Geographical Information
System (GIS) which is utilized in the development of APG's Real Property Master Plan.
All components of Alternative B would be feasible and easily implemented. All necessary equipment
and materials required for implementation of this alternative are readily available. Administrative
implementation of this alternative would require coordination between APG, the State of Maryland, and the
USEPA to ensure continuity of the long-term management and monitoring of the site. Implementation would
not affect additional future actions at the site. In fact, all components of Alternative B are also components of
each of the active remedial alternatives evaluated for Watson Creek.
Capital costs are estimated to be $38,000, and annual operation and maintenance (O&M) costs are
$46,000. Total present worth costs for this alternative based on a 30 year (5% discount rate) implementation
period are $615,000. Contingencies associated with the alternative would be minimal because the alternative
does not include any treatment or design components.
7.4 ALTERNATIVE C: PULL-SCALE DREDGING/SOUDIFICATION/LANDFILL
Under this alternative, sediment covering the entire area of Watson Creek (approximately 60
acres) would be dredged due to the widely dispersed inorganic contamination. Approximately 100,000 yd3
(a one-foot layer of sediment) would be removed. Prior to conducting any remedial activities at Watson
Creek, areas which contain UXO would need to be identified, and the UXO would be removed by qualified
personnel.
The removal activities would be performed using a cutterhead dredge hydraulic technique. This
technique was chosen because it is a widely used and economical method for removing large quantities of
sediment, which also minimizes sediment suspension. Once removed, the dredged sediment would be
replaced with a one-foot layer of sand. Replacement of the dredged sediment would provide a layer of
clean material for the benthic organisms to burrow while providing a barrier from any residual
contamination remaining in the Watson Creek sediment
The removed sediment would then be dewatered to reduce the water content to an acceptab
level. This dewatered sediment would then be mixed with a cementitious material in order to encapsuls
the contaminants within the sediment, isolating the contaminants from the environment. Although u
volume of the contaminants in the dredged sediment would not be reduced, contaminant mobility would be
significantly reduced because inorganic contaminants would be bound in the solidified sediment/cement
monolith through treatment The cured cement/sediment monolith would be sent to an off-site solid waste
landfill for final disposal.
Dredging normally*!* a simple construction process, and all equipment required for dredging is
available near the site. However, dredging at Watson Creek would be complicated by the unique hazards
associated with the site. Normal dredging methods may not be applicable to Watson Creek due to UXO
hazards. Techniques which minimize the suspension and migration of contaminated fines will be utilized
during UXO and dredging operations to reduce short-term effects to the aquatic environment and to protect
surface water quality in Watson Creek.
In addition to the dredging activities, Alternative C also includes all components of Alternative B (i.e.,
institutional controls, maintenance of existing physical security measures, public education programs, long-
term monitoring of site conditions, and five-year reviews).
The chemical-specific ARARs that apply to this remedial action are surface water criteria. The quality
of surface water in Watson Creek and the Gunpowder River would be protected during UXO clearance and
planting operations by utilizing techniques which would minimize the suspension and migration of
contaminated fines. All components of this alternative would be in compliance with action- and location-
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Section 7.0
Description of Alternatives
specific ARARs. Solidification, if properly implemented and performed within the established operating
parameters, would allow the treated sediment to pass TCLP and Paint Filter Liquid Tests. Disposal of the
treated sediment in_an off-site landfill would be conducted in accordance with the appropriate regulations:
Implementation of this option would take approximately 12 to 18 months for the design phase,
approximately 12 months for the surface clearance work, and approximately 12 to 18 months for the
dredging and treatment phase. These time estimates include regulatory review of the design, but do not take
potential delays due to weather and eagle nesting season into account.
The total capital costs to implement Alternative C are estimated at $156,000,000 and the total annual
O&M costs are estimated at $46,000. The total present worth of these costs, calculated with a 5% discount
rate over a lifetime of 30 years, is $157,000,000.
7.5 ALTERNATIVE D: "HOT SPOT" REMOVAL/SOUDIFICATION/LANDFILL
Under this alternative, 'hot spots" or areas of elevated concentration would be dredged from Watson
Creek. This alternative will help remove the highest concentrations of inorganics in the sediment, while
providing a significant cost savings compared to full-scale removal. The primary difference between
Alternative D and Alternative C is the volume of sediment to be removed. Under this alternative, only 'hot
spots" will be removed. Based on the identification of "hot spots," a volume of approximately 20,000 yd3
would be removed from Watson Creek. As discussed in Section 7.4, a one-foot layer of sediment would be
removed and replaced with sand, to ensure protection of benthic communities in these areas.
The same procedures used for full-scale dredging would be followed during "hot spot" removal
including: UXO clearance; sediment dredging; sand placement; and sedirjrtent dewatering, solidification,
and final disposition. In addition to the dredging activities. Alternative 0 also includes all components of
Alternative B (i.e., institutional controls, maintenance of existing physical security'measures, public education
programs, long-term monitoring of site conditions, and five-year reviews).
The dredging, treatment, and off-site disposal proposed in this alternative would remove the
contaminated sediment which could adversely affect benthic communities. The dredged sediment would be
treated using solidification to reduce the mobility of contaminants which could leach from the sediment, and
would be disposed in an off-site landfill. Although the volume of the contaminants in the dredged sediment
would not be reduced, contaminant mobility would be significantly reduced because inorganic contaminants
would be bound in the solidified sediment/cement monolith through treatment
Dredging normally is a simple construction process, and all equipment required for dredging is
available near the site. However, dredging at Watson Creek would be complicated by the unique hazards
associated with the site. Normal dredging methods may not be applicable to Watson Creek due to UXO
hazards. Techniques which minimize the suspension and migration of contaminated fines will be utilized
during UXO and dredging operations to reduce short-term effects to the aquatic environment and to protect
surface water quality in Watson Creek.
The chemical-specific ARARs that apply to this remedial action are surface water criteria. The quality
of surface water in Watson Creek and the Gunpowder River would be protected during UXO clearance and
planting operations by utilizing techniques which would minimize the suspension and migration of
contaminated fines. All components of this alternative would be in compliance with action- and location-
specific ARARs. Solidification, if properly implemented and performed within the established operating
parameters, would allow the treated sediment to pass TCLP and Paint Filter Liquid Tests. Disposal of the
treated sediment in an off-site landfill would be conducted in accordance with the appropriate regulations.
Implementation of this option would take approximately 10 to 16 months for the design phase,
approximately 8 months for the surface clearance work, and approximately 6 to 9 months for the dredging
and treatment phase. These time estimates include regulatory review of the design, but do not take potential
delays due to weather and eagle nesting season into account.
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Description ot Alternatives
The total capital costs to implement Alternative D are estimated at $36,000.000 and the total annual
O&M costs are estimated at $46,000. The total prese -t worth of these costs, calculated with a 5% discount
rate over a lifetime of 30 years, is $37.000,000.
7.6 ALTERNATIVE E: AQUATIC PHYTOREMEDIATION
Uptake of metals by emergent and aquatic plants is a passive approach to removing the metals from
the Watson Creek sediment. Under this alternative, emergent and aquatic plants capable of removing metals
from submerged sediment would be planted in the sediment. The plants would take up the metals in their
root systems; and deposit the metals in their roots, stems, and leaves. Eventually the plants would die, and
the low levels of metals within these plants would be dispersed within Watson Creek and the Gunpowder
River. Although plants used for aquatic phytoremediation are not generally preferred by terrestrial or
aquatic organisms as food sources, there is a possibility that these organisms could become exposed to
the metals in trie plants. This alternative would not address the potential pesticide contamination (an
estimated 0.5% of the total volume), but it is anticipated that the pesticide concentrations will diminish over
time due to natural processes occurring in the sediment The basic procedures used under this alternative
would be to clear Watson Creek of UXO, plant the emergent and a ic plants within the sediment anc
monitor the sediment for reductions in metals.
In addition to the planting activities. Alternate. a E also includ< ..I components of Alternative B (i.e..
institutional controls, maintenance of existing physical security measures, public education programs, long-
term monitoring of site conditions, and five-year reviews).
The chemical-specific ARARs that apply to this remedial action are surface water criteria. The quality
of surface water in Watson Creek and the Gunpowder River would be protected during UXO clearance and
planting operations by utilizing techniques which would minimize the suspension and migration of
contaminated fines. All components of this alternative would be in compliance with action- and location-
specific ARARs.
Implementation of this option would take approximately 12 to 18 months for the design phase,
approximately 12 months for the surface clearance work, and approximately 6 months for the planting phase.
These time estimates include regulatory review of the design, but do not take potential delays-due to weather
and eagle nesting season into account.
The total capital costs to implement Alternative E are estimated at $5,070,000 and the total annual
O&M costs are estimated at $46,000. The total present worth of these costs, calculated with a 5% discount
rate over a lifetime of 30 years, is $5,780,000.
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8.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
This section evaluates and compares each of the alternatives described in Section 7.0 with respect
to nine criteria used^o assess remedial alternatives as outlined in Section 300.430(e) of the NCP. Each of
the nine criteria are briefly described below. To aid in identifying and assessing relative strengths and
weaknesses of the remedial alternatives, this section provides a comparative analysis of alternatives. As
previously discussed, the alternatives are as follows:
No Action;
Limited Action;
Full-Scale Dredging/Solidification/Landfill;
'Hot Spot" Removal/Solidification/Landfill; and
Aquatic Phytoremediation.
These five alternatives are compared to highlight the differences between the alternatives and to identify
trade-offs in meeting the criteria.
8.1 NINE EVALUATION CRITERIA
Section 300.430(e) of the NCP lists nine criteria by which each remedial alternative must be
assessed. The acceptability or performance of each alternative against the criteria is evaluated individually so
that relative strengths and weaknesses may be identified.
The detailed criteria are briefly defined as follows:
Overall Protection of Human Health and the Environment is used to denote whether a
remedy provides adequate protection against harmful effects-and describes how human
health or environmental risks are eliminated, reduced, or controlled through treatment,
engineering controls, or institutional controls.
Compliance with ARARs addresses whether a remedy will meet all of the applicable or
relevant and appropriate requirements of Federal and State environmental statutes or
provides a basis for invoking a waiver.
Long-term Effectiveness and Permanence refers to the magnitude of residual risk and
the ability of a remedy to maintain reliable protection of human health and the environment,
over time, once clean-up goals have been met
Reduction of Toxlcity, Mobility, or Volume through Treatment is the anticipated
performance of the remedial actions as employed for each alternative.
'Short-term 'Effectiveness refers to the speed with which the remedy achieves protection,
as well as the remedy's potential to create adverse impacts on human health and the
environment during the construction and implementation period.
Implementability is the technical and administrative feasibility of a remedy, including the
availability of materials and services needed to implement the chosen solution.
Cost includes both capital and O&M costs.
State Acceptance indicates whether, based on its review of the FFS Report and Proposed
Plan, the State concurs with, opposes, or has no comment on the preferred alternative.
Community Acceptance assesses the public comments received on the FFS Report and
the Proposed Plan.
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Section 8.0
Summary of Comparative Analysis of Alternatives
The NCR (Section 300.430(0) states that the first two criteria, protection of human heatth and the
environment and compliance with ARARs, are the "threshold criteria* which must be met by the selected
remedial action. The-next five criteria are the "primary balancing criteria", and the trade-offs within this group
must be weighed. The preferred alternative is that alternative which is protective of human health and the
environment, is ARAR-compliant, and provides the best combination of primary balancing criteria attributes.
The final two criteria, state and community acceptance, are "modifying criteria" which are evaluated following
comments on the FFS report and the Proposed Plan.
8.2 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
The land-use condition assumed under Alternative A, No Action, would allow for unrestricted
residential, industrial, or recreational use. The levels of contamination in the Watson Creek sediment are
not a threat to human health. However, localized areas may exist where the levels of contaminants could
potentially adversely affect benthic communities. No controls would be implemented to prevent the
disturbance of the sediment; therefore, aquatic and terrestrial species could become exposed to the
contaminants within the fine-grained particles. The threshold criterion of protection of human health and
the environment would not be achieved by Alternative A.
Alternative 8, Limited Action, would provide reduction in adverse effects to benthic communities
by limiting future use and development of the affected area. Limited Action would include no further
actions to reduce or eliminate the contaminant source, or to reduce contaminant migration. However, the
principal contaminant migration pathway between Old O-Field and Watson Creek has been mitigated by
the construction of the QWTF. Additionally, unlike active treatment alternatives, the Limited Action
alternative would limit any activities which would disturb the sediment: thereby releasing contaminants
within the sediment into the surface water and negatively affecting aquatic communities within Watson
Creek. The long-term monitoring and review components of Alternative B would ensure that the action
provides an adequate protection of human health and the environment.
Alternatives C and D both involve dredging the contaminated sediment and then immobilizing the
contaminants in the dredged sediment by ex-situ solidification techniques. They differ only by the total
volume of sediment removed. In each case, the solidified sediment would be disposed in an off-site
landfill. Benthic communities would be protected from residual contamination by replacing the dredged
sediment with a layer of sand. However, by removing the sediment, the benthic communities presently
living in Watson Creek would also be removed and would not be protected.
Under Alternative E. the metals in the Watson Creek sediment would be removed by plant uptake.
However, as the plants die, they would distribute the metals back into the environment. This would result
in further mixing of the metals but. most likely, no net loss in the mass of metals. Additionally, the
emergent and aquatic plants added to Watson Creek could completely fill the entire area of free standing
water within Watson Creek, adversely affecting both aquatic and terrestrial communities dependent on the
current state of Watson Creek. This alternative would not address the pesticide contamination in the
southwestern tip of Watson 'Creek, except by the long-term decrease in concentrations due to naturally
occurring processes in the sediment.
Although implementation of Alternatives C, 0, and E would remove contaminants from Watson
Creek sediment, active removal of the sediment or planting operations could have adverse impacts on
both human health and the environment. Watson Creek is located adjacent to Old O-Field, an area known
for the presence of UXO. During dredging (Alternatives C and D) or planting operations (Alternative E),
there would be the potential for encountering UXO not only adjacent to Old O-Field, but throughout
Watson Creek. In the event that UXO was encountered, there would be potential for an explosion and/or
CWM release, resulting in detrimental effects to human health and the environment. Additionally, the
disruptive nature of UXO clearance, dredging (Alternatives C and D), and planting operations (Alternative
E) could cause a portion of the fine sediment particles to become suspended in the surface water in
Watson Creek. Disturbing these fine materials could mobilize the contaminants and adversely affect
aquatic organisms within Watson Creek. However, by temporarily closing the gate on the culvert between
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Section 8.0
Summary of Comparative Analysis of Alternatives
Watson Creek and the Gunpowder River during the field operations, the migration pathway for suspended
solids into the Gunpowder River would be eliminated.
8.3 COMPLIANCE WITH ARARS
Compliance with ARARs is a threshold criterion which must be met by the selected remedial
action. Chemical-specific ARARs for sediment, aside from surface water criteria, do not exist.
Alternatives B, C, 0, and E would all be capable of meeting.location-specific ARARs (including
Federal and State endangered species and migratory bird acts; water management and wetlands
regulations; and erosion and sediment control regulations). Surface water criteria and location-specific
ARARs will be considered during all sampling to minimize disturbance of the environment at Watson
Creek. In addition, during the more active alternatives, the quality of nearby surface water would be
protected by proper sediment control measures (chemical* and location-specific ARARs). The quality of
surface water in Watson Creek would be protected during UXO clearance, dredging (Alternatives C and
0), or planting operations (Alternative E) by utilizing techniques which would minimize the suspension of
contaminated fines (chemical- and location-specific ARARs). The quality of the surface water in the
Gunpowder River would be protected by closing the gate on the culvert between Watson Creek and the
Gunpowder River (chemical- and location-specific ARARs).
All components of Alternatives C, D, and E would be in compliance with action-specific ARARs.
Solidification, if properly implemented and performed within the established operating parameters, would
allow the treated sediment to pass TCLP and Paint Filter Liquid Tests. Disposal of the treated sediment in
an off-site landfill would be conducted in accordance with appropriate regulations. Selection of emergent
and aquatic plants and planting techniques would be performed in compliance with State and Federal
regulations. There are no action-specific ARARs for Alternatives A and B.
8.4 LONG-TERM EFFECTIVENESS AND PERMANENCE
Alternative A. No Action, would not meet this criterion because the risk would not be reduced
beyond current risks posed by the site. The principal contaminant migration pathway between Old O-Field
and Watson Creek has been mitigated by the construction of the GWTF. However, because activities
which could disturb the sediment and expose aquatic communities to the contaminants within the
suspended sediment would not be prevented under this alternative, the effectiveness of the No Action
alternative would be uncertain over the long term.
Alternative B, Limited Action, would provide long-term protection of human health and the
environment. Institutional restrictions currently in place at APG (i.e., access restrictions and security
measures) along with additional land-use restrictions (i.e., prohibiting any activities at Watson Creek other
than future monitoring) would prevent activities which could disturb the sediment: thereby preventing
aquatic communities from .being exposed to contaminants within the suspended sediment.
Alternatives C. D, and E would provide effective long-term and permanent protection by treating
the contaminated sediment within Watson Creek. The ecological receptor exposure pathway defined in
the RA would be eliminated using these alternatives.
Dredging combined with solidification as the treatment method under Alternatives C and D would
provide the greatest degree of long-term effectiveness and permanence by removing the top layer of
sediment and replacing it with a layer of sand. Once treated, the solidified sediment would be disposed in
an off-site landfill. Therefore, adverse impacts on benthic communities due to direct contact with the
contaminated sediment would be eliminated under these alternatives. However, the use of dredging would
remove existing benthic communities and aquatic plants. Although the benthic communities and aquatic
plants are expected to recover, it is not known if the removal of natural sediment and replacement with
sand would have long-term ecological effects on benthic communities within Watson Creek.
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Section 8.0
Summary or Comparative Analysis of Alternatives
Alternative E would provide long-term reduction of contaminant concentrations by removing
metals in the sediment using aquatic plant uptake. Adverse effects to benthic communities via direct
contact with the contaminants in the sediment would eventually be eliminated over a period of time under
Alternative E. The long-term effectiveness of phytoremediation depends on the ability of the introduced
emergent and aquatic plants to survive within Watson Creek, remove the metals from the sediment, and
evenly distribute the metals around Watson Creek once the plants die. Additionally, it is not known if the
plants introduced into Watson Creek would out-compete indigenous aquatic plants, benthic organisms,
and aquatic organisms. Therefore, the overall long-term effectiveness of Alternative E depends on the
survival of the introduced aquatic and emergent plants and their ability to co-exist with existing
communities within Watson Creek.
8.5 REDUCTION OF TOXICITY, MOBILITY OR VOLUME THROUGH TREATMENT
Alternatives A and B would not provide any reduction of toxicity, mobility, or volume of the
contaminants because removal or treatment of the contaminated sediment would not be components of
these alternatives. However, unlike active treatment alternatives, these alternatives would not include any
activities which would disturb the sediment, thereby releasing contaminants within the sediment into the
surface water and adversely affecting aquatic ecosystems within Watson Creek.
The dredging, treatment, and off-site disposal of contaminated sediment proposed under
Alternatives C and 0 would reduce the mobility of contaminants within the Watson Creek bottom
sediment. However, solidification processes will increase the total volume of sediment for disposal.
Aquatic plant uptake under Alternative E would passively remove the contaminants within the Watson
Creek sediment. The volume of the contaminants would not be reduced under Alternative E; however,
inorganic contaminants would be temporarily bound in the aquatic plants. The mobility of the inorganics
could increase as the plants die and disperse throughout Watson Creek.
8.6 SHORT-TERM EFFECTIVENESS
The length of time which would be required to implement the remediation alternatives follows in
increasing order Alternative B; Alternative 0; Alternative C; and Alternative E. Alternative B, the Limited
Action, could be implemented in 1 year. Alternative 0 would require approximately 10 to 16 months to
design and procure materials for dredging and solidification treatment; approximately 8 months to perform
surface clearance work; and approximately 6 to 9 months to treat and dispose of the dredged sediment.
Alternative C would require approximately 12 to 18 months to design and procure materials for dredging
and solidification treatment; approximately 12 months to perform surface clearance work; and
approximately 12 to 18 months to treat and dispose of the dredged sediment Alternative E would require
approximately 12 to 18 months to design and procure all necessary equipment for planting the aquatic
plants; approximately 12 months to perform surface clearance work; approximately 6 months for planting;
and over 30 years to reduce the levels of contaminants in the Watson Creek sediment to prevent adverse
effects to benthie communities. These time estimates include regulatory review of the design, but do not
take potential delays due to weather and eagle nesting season (Mid-December through Mid-April) into
account.
There would be no short-term adverse effects on the public, workers, or environment from
Alternatives A and B, because no active remedial actions would be implemented at Watson Creek.
Alternatives C, 0, and E would require that extensive UXO surveys be performed to ensure that
the equipment used in the actual remediation does not accidentally encounter UXO. Underwater UXO
surveys are difficult and expensive to implement, and are not likely to be 100% effective. However,
Alternatives C, 0, and E would each be designed to provide for short-term protection of the public,
workers, and the environment during implementation. In addition, proper personal protective equipment
would be required for all site workers.
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Section 8.0
Summary of Comparative Analysis of Alternatives
Secondly, elements of Alternatives C. D, and E each require that the sediment be disturbed. This
would likely result in the mixing and suspension of fine-grained particles through the water column, which
could expose aquatic and terrestrial species to the metals adsorbed onto these particles. However, proper
measures would bemused to minimize the suspension of contaminated fines in the surface water during
intrusive activities to protect the aquatic ecosystems within Watson Creek.
8.7 IMPLEMENTABILITY
Alternatives A and B would be the most easily implemented. Alternative A would require no
change in existing controls, and nearly all of the institutional control components of Alternative B are
already in place. Administrative implementation of Alternative B would require continued coordination
between APG, the State-o^ftJafytand, and the USEPA to ensure continuity of the long-term management
and monitoring of the sjtevvf'-
The equipment and materials required for dredging and treating the sediment proposed for
Alternatives C and 0 are commercially available. However, normal dredging methods may not be
applicable to Watson Creek due to UXO hazards. UXO are inherently dangerous under any
circumstances. UXO found in the creek will likely be in poor condition, making them even more unstable
and dangerous to handle. This greatly increases the safety concerns and environmental effects
associated with these alternatives. The logistics of successfully performing a UXO clearance over a large
body of water also affects the implementability of Alternatives C and 0. UXO clearance and dredging
methods which would minimize the suspension of contaminated sediment particles into the surface water
within Watson Creek would need to be implemented to prevent adverse effects on aquatic organisms. The
solidification technology selected for Alternatives. C and 0 has been demonstrated to be easily
implementable for the remediation of contaminated sediment at other sites. However, the large volume of
sediment to be removed and treated under Alternative C may cause logistical problems; therefore.
Alternative D may be more feasible.
The equipment and materials required for planting aquatic plants proposed under Alternative E
are commercially available. However, much like Alternatives C and 0, UXO hazards at Watson Creek
would complicate planting operations. Care would need to be taken during UXO clearance and planting
operations to minimize the suspension of contaminated fines into the surface water within Watson Creek
which could adversely affect aquatic organisms. Planting of aquatic plants has been demonstrated to be
easily implementable at other sites; however, proliferation of emergent and aquatic plants in Watson
Creek may cause problems in implementing Alternative E. It is also possible that the Watson Creek
sediment may not sustain a viable population of aquatic plants capable of metals uptake.
8.8 COST
Table 8-1 provides a comparison of the costs of the five alternatives under consideration. Total
capital costs, annual O&M costs, and present worth (30 years at a discount rate of 5%) for each alternative
are presented. The progression of total present worth from least expensive to most expensive alternative is:
Alternative A (no cost); Alternative B; Alternative E; Alternative 0; and Alternative C. Alternatives C and 0
are the most expensive alternatives because of the large quantities of sediment that would require removal,
treatment, and disposal.
8.9 STATE ACCEPTANCE
Based on a thorough review of the remedial alternatives and public comments, MDE concurs with
the preferred alternative.
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Section 8.0
Summary of Comparative Analysis of Alternatives
TABLE 8-1
COMPARISON OF COSTS FOR
WATSON CREEK REMEDIAL ALTERNATIVES
Alternative
A
B
C
0
E
Description
No Action
Limited Action
Full-Scale Dredging/
Solidification/
Landfill
'Hot Spot" Removal/
Solidification/
Landfill
Aquatic Phytoremediation
Costs in 1996 Dollars
Capital Cost
$0
$38,000
$156,000,000
$36,000,000
$5,070,000
Annual
O&M Cost
$0
$46,000
$46,000
$46,000
$46,000
Present
Worth
(30 yr, 5%
discount rate)
$0
$615,000
$157,000,000
$37,000,000
$5,780,000
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8-6
Record of Decision
Operable Unit 3
Final Document
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Section 8.0
Summary of Comparative Analysis of Alternatives
8.10 COMMUNITY ACCEPTANCE
A full transcript of the public meeting, held on July 28,1997, is available in the Administrative Record.
In general, the community appears to be in support of the selected remedy. Responses to written comments
received from the community are presented in the Responsiveness Summary (Appendix A).
8.11 SUMMARY OF DETAILED EVALUATION
The following is a brief summary of the evaluation of alternatives:
Alternative A (No Action) would not prevent the disturbance of the sediment by
trespassers or future development of the site. Therefore, Alternative A has been judged to
be incapable of providing overall protection of human health and the environment.
The implementation of Alternative B, Limited Action, would result in the establishment of
institutional controls to restrict access to the site, prevent development and disturbance of
the site, and inform workers and the public of the risks.
The active remediation alternatives. Alternatives C. D, and E. would result in the
remediation of the contaminated sediment. However, these alternatives pose relatively
high risks during implementation due to the potential presence of UXO in the sediment.
These alternatives would also result in the disturbance, and possible suspension, of the
sediment in the water column. This suspension may cause the aquatic and terrestrial
species who use Watson Creek to become exposed to the metals that are adsorbed onto
the fine-grained sediment particles.
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9.0 SELECTED REMEDY
Based upon consideration of the requirements of CERCLA, the detailed analysis of the alternatives,
and public comments, the Army and USEPA, with the concurrence of MDE, have chosen Alternative B,
Limited Action, as the most appropriate remedy for OU3 at Watson Creek in the O-Field Area of APG, MD.
As mentioned in Section 7.3, the selected remedy shall involve implementation of the following actions at
Watson Creek:
Institutional Controls. Institutional controls such as access restrictions and land-
use restrictions are currently in place at OU3. Watson Creek is located in a
restricted area of APG; therefore, access to this area is strictly enforced by APG
security. The restricted area is also subject to random patrols by armed security
personnel. Additional access restrictions may be required at Watson Creek in the
future if security practices are downgraded, however this is not anticipated
considering the current activities at APG.
Land-use restrictions will include: 1) the posting of signs prohibiting unauthorized
entry into Watson Creek; 2) the prohibition of activities at Watson Creek other than
future monitoring; 3) inputting these restrictions into APG's GIS, which is utilized in
the development of APG's Real Property Master Plan; and 4) incorporation of these
restrictions/prohibitions into any real property documents necessary for transferring
ownership from the Army, in the unlikely event that the Army sells this property.
The real property documents would also include a discussion of the NPL status of .
the site, as well as a description of the contamination at this site. The final wording,
and the location and number of signs would be determined during the workplan
development phase and through negotiations with USEPA and MDE. In addition,
the Directorate of Safety, Hearth and Environment (DSHE) would certify to the
USEPA on an annual basis that there have been no violations of these prohibitions.
If a violation has occurred, a description of the violation and corrective actions to be
taken would be provided.
Physical Security Measures, In conjunction with institutional controls, existing
physical security measures shall be maintained and additional security measures
will be implemented, as needed. Physical security measures include the posting of
' signs and maintenance of fences within the restricted area.
Public Education Programs. Educational programs shall be developed to inform
workers and local residents of the potential hazards due to the presence of UXO in
the sediment, and potential impacts to the aquatic environment caused by the
disturbance of contaminated sediment in Watson Creek..
, Long-Term jMonitoring of Site Conditions. Site conditions shall be monitored at
least once every five years in conjunction with the reviews described below.
Monitoring in Watson Creek will indicate whether any unforeseen changes would
raise the human health or ecological risks associated with Watson Creek. A long*
term sampling plan shall be developed for Watson Creek, by the Army, USEPA,
and MDE, to monitor the levels of contaminants in the sediment and
fish/invertebrate tissue. Because metals and 4.4-DDE are the contaminants of
concern in Watson Creek, all samples shall be analyzed for metals, and samples
collected in the vicinity of WC-39 shall also be analyzed for pesticides. Additional
analytes may also be added, as needed, to future monitoring. Based on the results
of chemical analysis, additional toxicity tests may also be warranted in the future.
Five-Year Reviews. Although this remedy does not allow for unrestricted use and
exposure, all available data shall be analyzed as part of the five-year review process
to determine whether additional remedial actions or site controls are required.
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Section 9.0
Selected Remedy
Most components of Alternative B have been implemented and are being maintained at the site.
Institutional controls and other provisions of this alternative are expected to minimize the risks posed to
aquatic communities-Jiving within Watson Creek. Implementation of this alternative shall not create any
adverse environmental impact.
9.1 BASIS FOR SELECTION
Alternative B will achieve risk reduction through institutional controls to prevent site access and
future development, and public education and awareness of the potential hazards due to the presence of
UXO in the sediment. Although Alternative B will not reduce the contaminant concentrations in the short term
as the more active remedial alternatives (Alternatives C, 0, and E), it will result in lower risks in the short term
and better overall protection of the aquatic environment Therefore, Alternative B is believed to provide the
best balance of trade-offs among alternatives with respect to the evaluation criteria.
9.2 COST OF SELECTED REMEDY
The total capital cost for implementation of Limited Action (Alternative B) at Watson Creek is
estimated at $38,000 and the total annual costs are estimated at $46,000. The total present worth of these
costs, calculated with a 5% discount rate over a lifetime of 30 years, is $615,000. Contingencies associated
with the alternative would be minimal because the alternative does not include any treatment or design
components. The costs for implementation of Alternative B are outlined in Table 9-1.
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Section 9.0
Selected Remecy
TABLE 9-1
. SUMMARY OF COSTS FOR THE SELECTED REMEDY
ALTERNATIVES: LIMITED ACTION
ITEM
COST
Capital Costs
Administrative Actions
Contingencies (60% of Capital Subtotal)
Permitting & Coordination
$23.000
$13.000
$2,000
Annual Operation and Maintenance Costs
Program Oversight
Long-Term Monitoring & Five- Year Reviews
Contingencies (25% of Annual Subtotal)
Present Worth of Annual O&M
(30 years, 5% discount rate)
Total Present Worth
(Capital and Annual Costs, 30 years at 5% discount rate)
. «w,ooa;
^^9,00*
$9.000
$577.000
$615,000
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10.0 STATUTORY DETERMINATIONS
The Army^ primary responsibility at its NPL sites is to undertake remedial actions that achieve
adequate protection-of human health and the environment. When complete, the selected remedial action for
this site must comply with applicable or relevant and appropriate environmental standards established under
Federal and State environmental laws unless a statutory waiver is justified. The selected remedy also must
be cost-effective and utilize permanent solutions and alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. Finally, the statutory preference for remedies that employ
treatment that permanently and significantly reduce the volume, toxicity, or mobility of hazardous waste as
their principal element should be satisfied, to the maximum extent practicable. The following sections discuss
how the selected remedy meets these statutory requirements.
10.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
The selected remedy protects human health and the environment by limiting disturbance of the
sediment and potential UXO which could occur through future use and development of the affected area.
10.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
Aside from surface water criteria, chemical-specific ARARs for sediment do not exist In addition,
there are no action-specific ARARs related to the components of the selected remedy. However, the
selected remedy is in compliance with location-specific ARARs, therefore meeting this criterion (Table 10-1).
10.3 COST-EFFECTIVENESS
The selected remedy is cost-effective because it has been determined to provide overall
effectiveness proportional to its costs, the net present worth being $615,000.
10.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE TREATMENT
TECHNOLOGIES (OR RESOURCE RECOVERY TECHNOLOGIES) TO THE MAXIMUM
EXTENT PRACTICABLE (MEP)
The Army, USEPA, and MDE have determined that the selected remedy represents the maximum
extent to which permanent solutions and treatment technologies can be utilized in a cost-effective manner for
action at Watson Creek. Removal and treatment options were considered in the FFS for this site, but were
eliminated because those alternatives posed a relatively high risk (due to the potential presence of UXO) and
could result in the suspension of sediment in the water column.
10.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
Based on the most accurate information available at this time, the Army, USEPA, and MDE believe
the selected remedy is protective of human health and the environment, complies with ARARs, is cost-
effective, and utilizes permanent solutions and alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. Although there is a statutory preference for remedies that
involve treatment as a principal element, the Army believes that the preferred alternative represents the most
effective means of risk reduction for the site, given the limited scope of the action.
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11.0 DOCUMENTATION OF SIGNIFICANT CHANGES |
The proposed plan for OU3. Watson Creek, 0-Field Area, APG. Aberdeen, MD. was released for
public comment 6» July 2, 1997. The Proposed Plan identified Alternative 8, Limited Action, as the
preferred alternative. The Army, USEPA, and MDE reviewed and considered all comments received
during the public meeting and during the public comment period. Upon review of these comments, it was
determined that no significant changes to the remedy, as originally identified in the Proposed Plan, are
necessary.
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12.0 REFERENCES )
Holland, A.F., Shayghnessay, AT., Scott, L.C., Dickens, V.A., Gerritsen, J.R.. and J.A. Rnansinghe.
1989. Long-term Benthic Monitoring and Assessment Program for the Maryland Portion of
Chesapeake Bay: Interpretive Report. Maryland Oept. Nat. Res., Power Plant Prog., Annapolis
MD. Report No: CBRM-LTB/EST-89-2.
ICF Kaiser Engineers, Inc. (ICF KE). 1990. Focused Feasibility Study of Groundwater Treatment Alternatives
for Old 0-Field, Aberdeen Proving Ground. Prepared for the U.S. Army Environmental Center.
ICF Kaiser Engineers, Inc. (ICF KE). 1991 a. Old 0-Field Aquifer Testing Program. Prepared for the U.S.
Army Environmental Center.
ICF Kaiser Engineers, Inc. (ICF KE). 1991b. Old O-FiekJ Groundwater Treatability Studies. Prepared for the
U.S. Army Environmental Center.
ICF Kaiser Engineers, Inc. ICF KE). 1991c. Old O-Field Groundwater Extraction and Treatment System
Conceptual Design. Prepared for the U.S. Army Environmental Center.
ICF Kaiser Engineers, Inc. (ICF KE). 1994. Focused Feasibility Study for the Old O-Field Source Area. Final.
Prepared for the U.S. Army Environmental Center. June 1994.
ICF Kaiser Engineers, Inc. (ICF KE). 1995. Remedial Investigation Report for the O-Field Area • Phase I.
Aberdeen Proving Ground, Maryland. Draft Final Document. Prepared for the U.S. Army
Environmental Center. August 1995.
ICF Kaiser Engineers, Inc. (ICF KE). 1997a. Focused Feasibility Study for Watson Creek, Edgewood Area,
Aberdeen Proving Ground • Maryland. Final Document. Prepared for the U.S. Army Environmental
Center. June 1997.
ICF Kaiser Engineers, Inc. (ICF KE). 1997b. Proposed Plan for Remedial Action, Aberdeen Proving Ground,
Watson Creek Sediment, Operable Unit 3. Final Document. Prepared for the U.S. Army
Environmental Center. June 1997.
Nemeth, G.. Murphy, J.M, Jr., and J.H. Zarzycki. 1983. Environmental Survey of the Edgewood Area of
Aberdeen Proving Ground, Maryland: U.S. Army Toxic and Hazardous Materials Agency. Aberdeen
Proving Ground, Maryland, Report No. DRXTH-AS-FR-82185.
Nemeth, G. 1989. RCRA Facility Assessment Report, Edgewood Area, Aberdeen Proving Ground, Maryland.
U.S. Army Environmental Hygiene Agency. Aberdeen Proving Ground, Maryland.
U.S. Army Environmental Hygiene Agency (USAEHA). 1977. An Assessment of Surface Waters. Aberdeen
Proving Ground. Edgewood Area, Maryland. Water Quality Biological Survey No. 24-0043-78.
U.S. Department of the Army. 1991a. Interim Action Proposed Plan. Old O-Field Site, Aberdeen Proving
Ground, MD. Prepared by ICF Kaiser Engineers.
U.S. Department of the Army. 1991b. Interim Action Record of Decision, Old O-Field Site, Aberdeen Proving
Ground, MD. Prepared by ICF Kaiser Engineers.
U.S. Department of the Army. 1994a. Proposed Plan for Interim Remedial Action, U.S. Army Aberdeen
Proving Ground, Old 0-Field Source Area (O-Field Operable Unit 2), Aberdeen Proving Ground,
Maryland. June 1994.
U.S. Department of the Army, 1994b. Interim Action Record of Decision, Old O-Field Source Area, Aberdeen
Proving Ground, MD. September 1994.
DAAA15-91-0-0014 12^1 ! Record of Decision
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Section 12.0
References
U.S. Department of the Army. 1995. Design Report for the Old O-Field Source Area. Final. Prepared by ICF
Kaiser Engineers. February 1995.
U.S. Geological Survey (USGS), U.S. Department of the Interior. 1991. Ground-Water, Surface-Water, and
Bottom-Sediment Contamination in the O-Field Area, Aberdeen Proving Ground, Maryland, and the
Possible Effects of Selected Remedial Actions on Ground-Water. Open-File Report 89-399.
Yon, R.L, Wenz, D.J., and C. Brenner. 1978. Information Relevant to Disposal of Hazardous Material at O-
Field, Aberdeen Proving Ground. Maryland. Record Evaluation Report 1978-1, Chemical Systems
Laboratory, Aberdeen Proving Ground, Maryland.
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APPENDIX A. RESPONSIVENESS SUMMARY |
The final component of the Record of Decision is the Responsiveness Summary. The purpose of
the Responsiveness Summary is to provide a summary of the public's comments, concerns, and
questions about Watson Creek and the Army's responses to these concerns.
During the public comment period, written comments were received by APG.
APG held a public meeting on July 28, 1997 to formally present the Focused Feasibility Study
Report and Proposed Plan, to answer questions, and to receive comments. The transcript of this meeting
is part of the administrative record for the site. All comments and concerns summarized below have been
considered by the Army and USEPA in selecting the final cleanup methods for Watson Creek.
This responsiveness summary is divided into the following sections:
A.1 Overview.
A.2 Background on community involvement.
A.3 Summary of comments received during the public comment period and APQ's
responses.
A.4 Sample newspaper notice announcing the public comment period and the public meeting.
A.1 OVERVIEW
At the time of the public comment period, the Army and USEPA had endorsed a preferred
alternative for the cleanup of Watson Creek. The preferred alternative consisted of long-term monitoring
of site conditions, continuation of access controls, and administrative actions..The Maryland Department
of the Environment (MDE) stated the proposed actions seemed appropriate based on the findings of the
risk assessment; however, MDE would consider the public's comments before providing a final
concurrence on the project
The community generally seems to be in support of the preferred alternative, with a few residents
preferring excavation.
A.2 BACKGROUND ON COMMUNITY INVOLVEMENT
Citizens' interest in the O-Field Study Area has been high, with the focus primarily on the
groundwater and the Old O-Field landfill, the primary source of contamination. Specific interest in Watson
Creek has been limited primarily to discussions at Restoration Advisory Board meetings and comments
by the APG Superfund Citizens Coalition. However, area residents are heavy recreational users of the
waterways surrpunding AP.Q and are concerned about any possible impacts to these waterways.
APG has maintained an active public involvement and information program regarding the O-Field
Study Area. Highlights of APG's community relations activities for Watson Creek follows:
APG began discussing possible cleanup methods for Watson Creek at Restoration
Advisory Board meetings in January 1995. Other meetings where APG presented
information on Watson Creek included July 1995, June 1996, and March 1997.
APG released the Proposed Plan for Watson Creek for public comment on July 2.1997.
Copies were available to the public at APG's information repositories at the Aberdeen and
Edgewood Branches of Harford County Library and Miller Library at Washington College.
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Appendix A
Responsiveness Summary
APG issued a press release announcing the availability of the Proposed Plan, the dates
of ffie public comment period, and the date and time of the public meeting to APG's
media list.
A 45-day public comment period on the Proposed Plan ran from July 2, 1997 to
August 15,1997.
APG placed newspaper advertisements announcing the public comment period and
meeting in The Aegis, the Cecil Whig, the Essex Times, The Avenue, and the Kent
County News.
APG prepared and published a fact sheet on the Proposed Plan. APG mailed copies of
this fact sheet to over 2,590 citizens and elected officials on its Installation Restoration
Program mailing list. The fact sheet included a form which citizens could use to send APG
their comments.
On July 28,1997, APG held a public meeting at the Edgewood Senior Center .
Edgewood, Man/tend, .Representatives of the Army, USEPA. and the MOE presented
information on ir.e site and their respective positions on the proposed cleanup
alternatives.
A.3 SUMMARY OP COMMENTS RECEIVED DURING THE PUBUC COMMENT PERIOD AND
AGENCY RESPONSES
Comments raised during the Watson Creek public comment period on the Focused Feasibility
Study Report and the Proposed Plan are summarized below. The comments are categorized by source.
COMMENTS FROM QUESTIONNAIRE INCLUDED WITH FACT SHEET
As part of its fact sheet on the Pre-osed Plan. APG included a ques- "naire that residents could
return with their comments. APG receiver 2 completed returns. The folio win 3 -.umber of responses were
in favor of:
0 No Action
7 Limited Action
1 Limited Action and Aquatic Phytoremediation
1 Full-Scale Dredging
1 Full-Scale Dredging and Aquatic Phytoremediation
2 Limited Removal
0 Aquatic Phytoremediation
Comments included on the forms were:
Comment 1: One resident expressed a preference for Limited Action combined with aquatic
Phytoremediation. He stated that if aquatic Phytoremediation is successful, the level of security and
monitoring could be phased down over time. He also stated he believes the Army has a responsibility to
neutralize and restore those areas.
APG Response: APG is studying phytoremediation and agrees it may be a valuable tool at certain sites.
Analysis of its use at this site showed that while it may help decrease the 'i-nited impacts to sediment-
dwelling organisms, the plants could completely fill the free-standing water within Watson Creek. This
could adversely affect aquatic life, waterfowl, and terrestrial animals which depend on the present state of
Watson Creek.
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Appendix A
Responsiveness Summary
It is unlikely the level of security would be decreased as long as the Army continues to own the site. APG
agrees that monitoring can be adjusted over time and phased down if appropriate. Also, the Army agrees
it has a responsibility to restore areas wherever necessary or practicable and this is a goal of the cleanup
program.
Comment 2: Thank you for your continued efforts to keep the community informed. This fact sheet does
an excellent job of explaining the situation and possibilities. It is not easy to communicate these issues
and your fact sheets always seem to be able to do it. I was at the Tollchester Fair last weekend with out of
town guests and your staff graciously took the time to discuss with them your program. You are to be
commended on your efforts. Keep it up!
APG Response: APG acknowledges and appreciates the comments.
Comment 3: One resident asked why the fact sheet did not contain the results on amphipod survival and
growth. The person also asked for further explanation on the statement that a person's contact with
sediment would be minimal since the water would wash it away. The commenter stated that a wader's
feet and leg skin is exposed to sediment.
APQ Response: APG will supply the commenter with the charts from the Focused Feasibility Study which
summarize the survival and growth results. APG will also supply the commenter with the information
repository locations which have copies of the full report for public review. The fact sheets present only a
brief summary of all the voluminous data gathered during the studies.
APG agrees that a wader's skin is in contact with the sediment. However, the risk assessment assumed
a person exposed to Watson Creek sediment would be trespassing and would not likely be standing in
one place long enough to result in an exposure route. Also, the sediment samples from Watson Creek
and the Gunpowder River were collected under at least two feet of water. This led to the conclusion the
water would be washing away the sediment and the length of time the wader's skin would be in contact
with the sediment would be minimal.
Comment 4: A resident commented that any unexploded ordnance should be located where possible and
destroyed.
APQ Response; APG is working on the issue of unexploded ordnance, particularly in areas near APG's
boundaries and along shoreline areas. This work includes looking at technology that is on the cutting
edge for locating the ordnance, determining what its contents are, and disposal methods. APG will
continue to keep residents informed about these studies and actions.
Comment 5: A resident commented that her main concern is drinking water. She stated it is most
important that APG constantly monitor the levels of impurities and be sure the water is safe at all times at
any cost.
APG Response: APG agrees that ensuring any contamination found at APG does not impact drinking
water supplies is a priority. The Installation Restoration Program has installed an extensive monitoring
well network, with an emphasis along the APG boundaries, and is conducting comprehensive geologic
studies to ensure any contamination is not moving off-post. Protection of public health and the
environment is more highly weighted than cost in the remediation process.
Comment 6: A resident expressed a preference for Alternative C, full-scale dredging, with disposal in a
concrete vault where it cannot leach out. She also stated toxins must be kept out of the environment.
even diluted.
APG Response: Dredging followed by solidification was selected for detailed analysis because this
process would immobilize the contaminants (primarily metals) in concrete blocks. Prior to disposal, the
solidified blocks would be required to pass two tests, the Toxicity Characteristic Leaching Procedure
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Appendix A
Responstvqnasa Summary
(TCLP) and Paint Filter Tests, to ensure that the contaminants in the blocks would not readily migrate into
the environment. However, APG's analysis found this alternative to be less favorable than Limited Action
in terms of overall protection of human health and the environment and cost-effectiveness. Full-scale
dredging could also have short-term impacts on human health and the environment, due to potential UXO
and the suspension and migration of contaminated fines. Therefore. APG and USEPA selected Limited
Action which will be more protective of human health and the environment than full-scale dredging. Under
the Limited Action alternative, the contaminants in the sediment would be left undisturbed; thereby
minimizing adverse impacts on the environment.
COMMENTS AT JULY 28.1997 PUBLIC MEETING
No oral or written comments were presented at the July 28 public meeting on the Proposed Plan.
A full transcript of the meeting is available at APG's information repositories.
COMMENTS FROM APG SUPERFUND CITIZENS COALITION
APGSCC is the recipient of two Technical Assistance Grants from the U.S. Environmental
Protection Agency. The Coalition submitted comments prepared by their consultant the University of
Maryland Program in Toxicology. APGSCC stated it supports the preferred alternative of Limited Action.
They also had several specific comments which are summarized below:
Comment?; The Toxicology Program noted it has raised previous concerns regarding the adequacy of
using one bioassay to assess bioavailability, without other supporting science and logic.
APG Response; Hyalella azteca (H. azteca) was selected as the organism for further testing at Watson
Creek after giving serious consideration to several test alternatives, one of which was to use two
bioassays at each sample location. H. azteca was used in all sampling rounds to maintain a consistent
test organism throughout all phases of testing, allowing the comparison of data from all sampling phases.
The use of H. azteca was approved by the U.S. Environmental Protection Agency and Maryland
Department of the Environment, as well as the multi-agency Biological Technical Assistance Group. Also.
the scientific literature suggests that H. azteca is generally a sensitive indicator of sediment toxicity. As
part of the long-term monitoring, APG will be again evaluating which organisms are appropriate.
Comment 8: The Toxicology Program questioned the accuracy of the costs presented for the other
alternatives and suggested APG's current budget needed to be considered n selecting an alternative.
APG Response; APG believes the costs presented for the alternatives are reasonably accurate
estimates. The Focused Feasibility Study report contains detailed cost information on the components that
make up the total cost of each alternative. APG agrees that priorities need to be set in deciding which
areas to address first. However, cost is not the primary factor considered in the selection of an
appropriate remedy. Cost is considered only in relation to remedies that are equivalent in effect but vary
in their cost Protection of p"ublic health and the environment is the factor which receives the greatest
weight in the evaluation of an appropriate cleanup plan.
Comment 9; The Toxicology Program questioned whether APG would be further investigating the marsh
area south of Watson Creek. They stated it would not make sense to excavate the sediment if the marsh
is a potential source.
APG Response: APG plans to conduct additional sampling in the New O-Field marsh area, located south
of Watson Creek, in late 1997. Based on an analysis of historical information and the results of this
investigation, APG will issue a proposed plan for any required actions to the public for review.
A.4 SAMPLE NEWSPAPER NOTICE ANNOUNCING THE PUBLIC COMMENT PERIOD AND THE
PUBLIC MEETING
The following is a copy of the newspaper notice printed in the Cecil Whig on July 2.1997.
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US ARMY
ENVIRONMENTAL CENTER
-------
U.S. ARMY INVITES PUBLIC COMMENT
ON PROPOSED PLAN FOR WATSON CREEK
Aberdeen Pjpving Ground (APC) invites the public to comment on its Proposed Plin for an environmental action
3t Watson Creek, located in the Edgewood Area of A PC. The public may submit written comments on the
Proposed Plan during the 45-day comment period which runs from July 2 to August 15.1997. Comments must b«
postmarked by-August 15 and may be sent to:
Mr. Ken Stichiw, U.S. Army Aberdeen Proving Ground *
Oirectorateof Safety, Health, and Environment
A TIN: STEAP-SH-ER. Aberdeen Proving Ground, MO
:iOIO-5523:or
Mr. Steve Hirjh. U.S. Environmental Prelection Agencv Rtfton III
341 Chestnut Building(3HW50). Philadelphia^ 'l 9107; or
Mr. John Fairbank. MarylandDeparunentof the Environment
Waste ManagementOivision
2500 Broening Highway, Baltimore. MD 21224
PUBLIC MEETING
APG invites Republic to attend a public meeting on:
DATE: Monday, Jury 28.. 1997-. ".:?•"
TIME: 7:00 pjn. - poster sewion •' '. . -^..
7:30 pjn. • presentation
8:15 pjn. -comments/poster session
PLACE: Edgewood Senior Center
• 1000 Gatewsy Road . •
Edgewood, MO 21040 :
A PC has prepared a fact sheet on the Proposed Plan which includes a comment form that can be returned to
APG. You can request a copy of the fact sheet by calling APG's 24-hour Environmental Information Line at
(410)272-3342 or (300) APG-9998.
SITE HISTORY AND ENVIRONMENTAL STUDIES -
. Watson Creek is a 60-acrc body of water that lies east of the O-Field Study Area. The study arcs includes Old
0-Field and New O-Field. From the late 1930s until 1953. the Army used the five-acre landfill at Old O-Field for
(he disposal of chemical warfare agents, munitions, equipment and other waste materials. New O-Field was'
primarily an open burning and disposal area from the mid-1950s to the late 1970s. APG no longer uses either area
for disposal. Since 1995 APG has been treating the groundwater at Old O-Field. The Army also is installing e>-
multi-layer cover system over the Old O-Field landfill.
APG initiated studies of the Watson Creek surface water and sediment to examine any impacts from historical
and testing activities. Studies found no human health impacts and limited or no impacts to aquatic life from (1m
sediment in Watson Creek.
ALTERNATIVES FOR SEDIMENT REMEDIATION
APG. EPA and MOE evaluated the following alternatives for reducing the possible limited impacts to aquatic life
posed by the sediments in Watson Creek.
Alternative A: No Action - The law requires APG evaluate taking no action to establish a baseline for comparison
with other alternatives. Cost: SO
Alternative 8: Limited Action • Limited action consists of long-term monitoring of site conditions, continuation
of access controls, and administrative actions. This alternative would reduce adverse effects to sediment-dwelling
communities by limiting future use and development, thus limiting the disturbance of the sediment which could
have adverse impacts on the organisms. The Army would conduct long-term environmental monitoring of sice
conditions through periodic sediment sampling. Cost: Ml5,000 over JO yean
Alternative C: Full-Scale Dredging, Solidification, and Disposal in an Off-Site Landfill - The Army would
remove the first foot pf sediment (about 127.000 tons) by dredging. After removing the sediment. APG would
place clean sand in Watson Creek. The dredged sediment would be dewatered. solidified on site, and disposed at
an off-site industrial waste landfill or rubble landfill. Cost: SI 57.000,000 over 30 yean
Alternative D: Limited Removal, Solidification, and Disposal in an Off-Site Landfill - Thi. alternative
involves the same activities as Alternative C. except the Army would remove limited areas of sediment amounting
to 25.000 tons. Cost: $37,000,000 over 30 yean
Alternative E: Aquatic Pnytoremediatlon • The Army would place about 110.000 aquatic plants capable of
removing metals from sediment in Watson Creek. The plants would take up the metals into their roots, stems, and
leaves. Eventually the plants would die and the low levels of metals within these plants would be dispersed in
Watson Creek and the Gunpowder River. Cost: S5.780.000 over 30 years
Based on their analysis. APG and EPA prefer Alternative B. Limited Action. The MOE will
finalize its position after reviewing public comments. •
The preferred alternative may be modified or a new alternative may be developed based on public input. The
final remedy selected will b« documented in a Record of Decision (hat summarizes (he decision-making process.
APG will summarize and respond to all written comments received during the comment period as pan of the
Record of Decision. Copies of the Focused Feasibility Study and the Proposed Plan are at the APG information
repositories located at the Edgewood and Aberdeen branches of Harford County Library and Miller Library at
Washington College in Kent County.
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