United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R04-92/126
September 1992
v°/EPA Superfund
Record of Decision:
Milan Army Ammunition Plant,
TN
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NOTICE
The appendices Hsted in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement, but adds no further applicable information to
the content of the document All supplemental material is, however, contained in the administrative record
for this site.
.e- ' e
.1 : .' ' i
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R04-92/126
3. Recipient' Acceedon Mo.
4. THIe end Subtitle
SUPERFUND RECORD OF .DECISION
Milan Army Ammunition Plant, TN
First Remedial Action - Interim
5. Report DM*
09/30792
7. Authors)
8- Performing Organization Rept No.
». Performing Organization Harm and Addrcu
10, Project/Taak/Work Unit No.
11. Contr»ct(C) or Grant(G) No.
(C)
(G)
12. Sponaorlng Organization Name end Addreae
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Conrad
800/000
15. Supplementary Note*
PB93-964022
16. Abatnct (Limit: 200 word*)
The 22,436-acre Milan Army Ammunition Plant (MAAP) is located in western Tennessee,
5 miles east of Milan, Tennessee. The facility was constructed in 1941 to produce and
store fuses, boosters, and small- and large-caliber ammunition. The site is located
in a primarily rural area where land use is predominantly agricultural, and there are
scattered residences to the north and east of the facility boundary. The Memphis Sand
aquifer of the Claiborne Group is used as the major source of potable water in this
area. The site lies within the coastal plain province of the Mississippi Embayment.
Of the original 13 onsite process areas, only seven are in use today. One of these is
the O-line area at MAAP, which was built in 1941. Its major function since then has
been to remove explosives from bombs and projectiles by injecting high pressure
streams of hot water and steam into the shells of the munitions. The types of
explosives handled at the facility include 2,4,6-trinitrotoluene (TNT) and RDX.
Wastewater contaminated with explosives was discharged from the washout operations
through a series of baffled concrete sumps where cooling caused significant amounts of
explosives to precipitate out of the waste stream. Effluent from the sumps was
(See Attached Page)
TN
17. Document AraJyaJ* a. Descriptor*
Record of Decision - Milan Army Ammunition Plant,
First Remedial Action - Interim
Contaminated Medium: gw
Key Contaminants: VOCs (carbon disulfide), other organics (HMX, RDX, 2,4,6-TNT,
2,4-DNT, 2,6-DNT, 1,3-DNB, 1,3,5-trinitrobenzene, nitrobenzene),
inorganics (nitrate)
b. UmtHiMV/Open-Emtad Term*
e. COSATI Reid/Group
18. Availability Statement
18. Security Clue (Thla Report)
None
20. Security Clue (Thi* Page)
None
21. No.olPag*»
70
22. Price
(S**ANSU38.18)
Set Instruction* on Renme
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-3S)
Department of Commerce
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EPA/ROD/R04-92/126
Milan Army Ammunition Plant, TN
First Remedial Action - Interim
Abstract (Continued)
initially discharged to an open ditch, which ran through the O-line area. In 1942,
eleven individual surface impoundments with a total capacity of 5.5 million gallons were
excavated to receive the effluent before discharge to the open ditch. In 1978, during
several investigations, the Army observed that all of the wastewater ponds were full and
overflowing into onsite soil, and that 3 of the 11 water supply wells sampled were
contaminated with explosives. After onsite ground water contamination was determined to
be a direct result of the improper use of 0-line ponds, use was discontinued. In 1981,
the ponds were drained and the effluent was treated in an offsite facility. A closure
plan was implemented in 1984, the ponds were filled and covered with clay, and the area
was revegetated. This ROD addresses an interim remedy for the contaminated ground water
beneath and immediately downgradient from the former ponds as OU1. Future RODs will
address contaminated soil, sediment, and surface water as well as any additional ground
water contamination further downgradient. The primary contaminants of concern affecting
the ground water are VOCs, including carbon disulfide; other organics, including HMX,
RDX, 2,4,6-TNT, 2,4-DNT, 2,6-DNT, 1,3-DNB, 1,3,5-trinitrobenzene, and nitrobenzene; and
inorganics, including nitrate.
The selected interim remedial action for this site includes pumping and pretreatment of
contaminated ground water immediately downgradient of the former 0-line ponds using
electrochemical precipitation to remove inorganics, followed by onsite filtration to
remove suspended solids, and UV oxidation to destroy the majority of the organic
contaminants, and granular activated carbon (GAC) to remove the remaining organic
compounds; re-injecting the treated water onsite upgradient of the former ponds;
analyzing the precipitated filter cake and the carbon filters for hazardous waste
characteristics and disposing of them offsite accordingly; monitoring ground water; and
implementing institutional controls, including ground water use restrictions. The
estimated present worth cost for this interim remedial action is $26,980,000, which
includes an annual O&M cost of $1,413,000 for 30 years.
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific ground water discharge levels are based on best practicable treatment,
are slightly higher than human health-risk standards (HBN) and SDWA MCLs, and include
nitrate 10,000 ug/1 (MCL); carbon disulfide 3,500 ug/1 (HBN); 1,3-dinitrobenzene 5 ug/1
(HBN); 2,4-dinitrotoluene 0.5 ug/1 (HBN); 2,6-dinitrotoluene 0.5 mg/1 (HBN); HMX
2,000 ug/1 (HBN); nitrobenzene 17.5 ug/1 (HBN); RDX 10 ug/1 (HBN); 1,3, 5-trinitrobenzene
20 ug/1 (HBN); and 2,4,6-TNT 10 ug/1 (HBN). Health-based standards will be fully met in
the final remedial action under one final ROD addressing ground water immediately
downgradient of the former ponds (OU1), soil in and around the former pond (OU2), and the
ground water plume (OU14).
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r. 7
MILAN ARMY
AMMUNITION PLANT (MAAP)
O-LINE PONDS
GROUNDWATER OPERABLE UNIT
Milan, Tennessee
INTERIM ACTION
RECORD OF DECISION
FINAL DOCUMENT
September 30, 1992
In accordance with Armyf Regulation 200-2, this document is
intended to comply with the National Environmental Policy Act
(NEPA) of 1969.
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DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
O-LJne Ponds Area, Milan Army Ammunition Plant (MAAP), Milan, Tennessee
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for Operable Unit One (OU 1) at
the O-Line Ponds Area, Milan Army Ammunition Plant, Milan, Tennessee. The selected remedial 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 CFR 300). This decision document explains the factual
basis for selecting the remedy for OU 1 and the rationale for the final decision. The information
supporting this remedial action decision is contained in the Administrative Record for this site.
The U.S. Environmental Protection Agency and the State of Tennessee concur 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
The goal of the overall cleanup activities at the site is to reduce the levels of contaminants to
below health-based concentrations, such that no adverse health effects will result from current and future
off-post or on-post use. Presently, more information is available concerning the nature and extent of
groundwater contamination than is known about soil, surface water, and sediment contamination within
the O-Line Ponds area Because contaminated groundwater potentially poses an unacceptably high level
of risk to human health and is better defined, this environmental medium has been separated from the
others. This separation of environmental media into Operable Units (OU) allows the Army to begin
groundwater cleanup prior to full assessment of the entire site.
The Operable Units are defined as follows: Operable Unit One (OU 1) addresses contaminated
groundwater beneath and immediately downgradient from the former ponds which has been contaminated
by past disposal practices at the ponds. Operable Unit Two (OU 2) addresses contaminated soils
beneath and around the former ponds and surface water and sediment in the drainage ditch that flows
along the east and north sides of the ponds, which may have become contaminated as a result of past
disposal practices. Operable Unit 14 (OU 14) addresses the area downgradient (to the north and
northwest) of OU 1 and OU 2, including Line K. This Record of Decision presents specific remedies that
were considered for OU 1 only. Remediation methods for OU 2 and OU 14 will be selected as separate
actions.
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The major components selected for remediating OU 1 are as follows:
Downgradieht extraction of contaminated groundwater using extraction wells;
On-site treatment of extracted groundwater using electrochemical precipitation to remove
inorganic constituents; ultraviolet (UV)-oxidation to destroy the majority of the organic
contaminants in the water; and granular activated carbon (GAC) to remove remaining
organic compounds;
Re-injection of treated groundwater upgradient of the former ponds;
Monitoring well installation to determine extraction effectiveness; and
Institutional controls will be used to prevent human exposure to the contaminated
groundwater.
The principal threat at this site, groundwater contaminated with explosives, will be addressed by
removing contaminated water from the aquifer and permanently treating the water with a combination of
electrochemical precipitation to remove inorganics and UV-oxidation with GAC to remove organic
contaminants from the water.
In pursuit of the overall site goal of reducing the levels of contaminants to health-based levels, UV-
oxidation, an innovative technology, will be used to remove explosives compounds from extracted
groundwater. This technology was selected because of uncertainties regarding the ability of more
commonly-used technologies in reducing the concentrations of contaminants to the health-based levels.
UV-oxidation has not previously been applied in full-scale systems to remove these contaminants;
however, it has the potential to meet the stringent criteria
The Army has elected to perform this phase of groundwater cleanup under an Interim Action
Record of Decision (ROD), which allows for treatment system design, construction, operation (using the
discharge limits listed herein, which for several explosives compounds are higher than health-based
concentrations), and performance evaluation for a set period of time. At the end of the performance
evaluation period, the treatment system capabilities and discharge levels will be reevaluated. If the health-
based levels for any of the contaminants of concern have changed in the interim, these new values will
be considered as the treatment goals. A final action remedy will be selected which satisfies all health
based clean-up levels or provides technical data, consistent with CERCLA and the National Contingency
Plan, which justifies alternative standards. The remedy selected in the interim action is consistent with
planned future actions to the extent possible.
Because this interim remedial action requires that the further migration of contaminated
groundwater within the O-Line Ponds area be stopped, and the concentrations of contaminants in
groundwater be greatly reduced, it is consistent with any planned future actions.
STATUTORY DETERMINATIONS
This interim action is protective of human health and the environment, complies with Federal and
State applicable or relevant and appropriate requirements for this limited scope action, and is cost
effective. Although this interim action is not intended to fully address the statutory mandate for
permanence and treatment to the maximum extent practicable, this interim action utilizes treatment and
thus is in furtherance of that statutory mandate. Because this action does not constitute the final remedy
for groundwater at the site, the statutory preference for remedies that employ treatment that reduces
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toxicity, mobility or volume as a principal element, although partially addressed in this remedy, will be
addressed by the final response action for groundwater. Subsequent actions are planned to address fully
the threats posed by the conditions in the groundwater at this site.
Because this remedy will result in hazardous substances remaining on site above health-based
levels, a review will be conducted to ensure that the remedy continues to provide adequate protection of
human health and the environment within five years after commencement of the remediation. Because
this is an interim action ROD, review of this site and of this remedy will be continuing as the Army
continues to develop final remedial alternatives for groundwater at the site.
Everette B. Grumpier III Date
Lieutenant Colonel, U.S. Army
Commanding Officer, Milan Army Ammunition Plant
Lewis D. Walker Date
Deputy Assistant Secretary of the Army
(Environment, Safety, and Occupational Health)
in
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f\ /7 3 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
* k i *./
.^ REGION IV
«i ooo-1
345 COURTLANO STREET. N.E.
ATLANTA. GEORGIA 3O365
SEP 3 0 1992
4WD-FFB
CERTIFIED MAIL
RETURN RECEIPT REQUESTED
Mr. Lewis D. Walker
Deputy Assistant Secretary of the Army
(Environment, Safety and Occupational Health)
Attn: SAILE-ESOH
The Pentagon, Room 2E577
Washington, D.C. 20310-0110
Re: Interim Remedial Action Record of Decision
0-Line Ponds Groundwater Operable Unit
Milan Army Ammunition Plant
Milan, Tennessee
Dear Mr. Walker:
The United States Environmental Protection Agency (EPA) has
reviewed the Department of the Army's Interim Remedial Action
Record of Decision for the 0-Line Ponds Groundwater Operable Unit
at the Milan Army Ammunition Plant pursuant to the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980,
as amended by the Superfund Amendments and Reauthorization Act of
1986. EPA concurs in the findings and selected remedy presented
in the Interim Record of Decision.
Sincerely yours,
Patrick M. Tobin
Deputy Regional Administrator
cc: Commissioner J. A. Luna, Tennessee Department
of Environment and Conservation
Lt. Colonel Everette B. Grumpier III,
Commanding Officer, MAAP
iv
Printed on Recycled Paper
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STATE OF TENNESSEE
DEPARTMENT OF ENVIRONMENT AND CONSERVATION
Mr. Lewis D. Walker
Deputy Assistant Secretary of the Army
OSHA-I, LE
Office of the Assistant Secretary
Department of the Army
Washington, D.C. 20310-0103
Ref. 27-505 MAAP O-Line Ponds OPU-1 ROD
Dear Mr. Walker:
The Tennessee Department of Environment and Conservation has
reviewed the final Interim Action Record of Decision
submitted on September 30, 1992. This document has reference
to the groundwater remediation operable unit at the O-Line
Ponds Area at the Milan Army Ammunition Plant located in
Milan, Tennessee. The Department concurs with the findings
and the selected interim remedial action stated in this
Record of Decision.
If you should have any questions regarding this matter please
contact me at (615) 532-0228 or Mr. Ron Sells, TDEC Project
Manager at (901) 423-6600.
Sincere
_ :ing
Administrator, Bure^V of Environment
Tn Dept of Environment & Conservation
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TABLE OF CONTENTS
Section Page
DECLARATION FOR THE RECORD OF DECISION i
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY CONCURRENCE LETTER . iv
STATE OF TENNESSEE DEPARTMENT OF ENVIRONMENT AND CONSERVATION
CONCURRENCE LETTER v
1.0 SITE NAME. LOCATION AND DESCRIPTION 1-1
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 2-1
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 3-1
4.0 SCOPE AND ROLE OF OPERABLE UNIT OR RESPONSE ACTION 4-1
5.0 SITE CHARACTERISTICS 5-1
5.1 HYDROGEOLOGIC SETTING 5-1
5.2 CONTAMINATION ASSESSMENT 5-1
5.Z1 Summary of Remedial Investigation Results 5-3
5.2.2 Summary of Post-RI Sampling and Analysis 5-3
5.2.3 Extent of Groundwater Contamination 5-3
6.0 SUMMARY OF SITE RISKS 6-1
6.1 CHEMICALS OF POTENTIAL CONCERN 6-1
6.2 EXPOSURE ASSESSMENT 6-5
6.3 TOXICITY ASSESSMENT 6-5
6.4 RISK CHARACTERIZATION 6-5
6.5 FUTURE OFF-SITE HUMAN HEALTH RISKS 6-6
6.6 ECOLOGICAL IMPACTS : 6-6
6.7 BASELINE RISK ASSESSMENT SUMMARY 6-7
7.0 DESCRIPTION OF ALTERNATIVES 7-1
7.1 ALTERNATIVE T-1: NO ACTION 7-1
7.2 ALTERNATIVE T-2: LIMITED ACTION 7-1
7.3 COMMON ELEMENTS IN TREATMENT ALTERNATIVES T-3 THROUGH T-8 . . . 7-1
7.3.1 Interim Remedial Action Treatment System Goals 7-2
7.3.2 Extraction System 7-2
7.3.3 Discharge Options 7-3
7.3.4 Other Assumptions Used in the Cost Estimates 7-3
7.4 ALTERNATIVE T-3: UV-OXIDATION/RE-INJECTION 7-3
7.5 ALTERNATIVET-4: PRECI PITATION/U V-OXIDATION/ION
EXCHANGE/SURFACE WATER DISCHARGE 7-4
7.6 ALTERNATIVE T-5: PRECIPFTATION/GRANULAR ACTIVATED CARBON
(GACJ/RE-INJECTION 7-5
vi
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TABLE OF CONTENTS (Continued)
Section Page
7.7 ALTERNATIVE T-6: PRECIPITATION/GRANULAR ACTIVATED CARBON
(GAC)/ION EXCHANGE/SURFACE WATER
DISCHARGE 7-6
7.8 ALTERNATIVE T-7: PRECIPITATION/UV-OXIDATION/GAC/RE-
INJECTION 7-6
7.9 ALTERNATIVE T-8: PRECIPITATION/UV-OXIDATION/GAC/ION
EXCHANGE/SURFACE WATER DISCHARGE 7-7
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 8-2
8.4 LONG-TERM EFFECTIVENESS AND PERMANENCE 8-3
8.5 REDUCTION OF TOXICITY, MOBILITY OR VOLUME THROUGH
TREATMENT 8-3
8.6 SHORT-TERM EFFECTIVENESS 8-4
8.7 IMPLEMENTABIUTY 8-4
8.8 COST 8-4
8.9 STATE ACCEPTANCE 8-6
8.10 COMMUNITY ACCEPTANCE 8-6
8.11 SUMMARY OF DETAILED EVALUATION 8-6
g.O SELECTED REMEDY 9-1
9.1 EXTRACTION SYSTEM 9-1
9.2 TREATMENT AND DISCHARGE SYSTEM: ALTERNATIVE T-7 9-1
9.2.1 Electrochemical Precipitation 9-4
9.2.2 UV-Qxidation ; 9-4
9.2.3 Granular Activated Carbon 9-4
9.2.4 Re-iniection 9-5
9.3 PERFORMANCE MONITORING 9-5
9.3.1 Effluent Monitoring Program 9-5
9.4 TREATMENT SYSTEM PERFORMANCE EVALUATION 9-6
9.5 INSTITUTIONAL CONTROLS 9-6
9.6 REMEDIATION GOALS 9-7
9.6.1 Federal MCLs and Tennessee Groundwater Standards 9-7
9.6.2 Health Advisories 9-7
9.6.3 Other Risk-Based Guidance 9-9
9.6.4 Estimate of Off-Site Concentrations of Contaminants after
Remediation 9-9
9.6.5 Achievement of Remediation Goals 9-11
9.7 COST OF THE SELECTED REMEDY 9-11
10.0 STATUTORY DETERMINATIONS 10-1
10.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT 10-1
VII
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TABLE OF CONTENTS (Continued)
Section Page
10.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS 10-1
10.2.1 Action-Specific ARARs 10-1
10.2.2 Chemical-Specific ARARs 10-4
10.2.3 Location-Specific ARARs 10-4
10.3 COST EFFECTIVENESS '. 10-4
10.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE TREATMENT
TECHNOLOGIES (OR RESOURCE RECOVERY TECHNOLOGIES) TO THE
MAXIMUM EXTENT PRACTICABLE 10-4
10.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT 10-7
11.0 DOCUMENTATION OF SIGNIFICANT DIFFERENCES 11-1
12.0 REFERENCES 12-1
APPENDIX A
RESPONSIVENESS SUMMARY
vili
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UST OF FIGURES
Figure Page
1-1 Location of MAAP in Western Tennessee 1-2
1-2 Active Process Areas Within MAAP 1-3
2-1 O-LJne and 0-Line Ponds Location 2-2
2-2 Schematic of O-U'ne Ponds During Use 2-3
5-1 Groundwater Flow Directions and Horizontal Hydraulic Gradients 5-2
5-2 RDX Concentrations Downgradient of the O-LJne Ponds Area 5-4
5-3 2,4,6-TNT Concentrations Downgradient of the O-Line Ponds Area 5-5
9-1 Location of Extraction and Re-Injection Well Systems 9-2
9-2 Alternative T-7 Flow Diagram .9-3
UST OF TABLES
Table Page
6-1 Chemicals of Potential Concern in Groundwater Immediately Downgradient of the O-
Line Ponds 6-2
6-2 Potential Risks Associated With Ingestion of Groundwater by Future Residents Under
the Residential Land Use Scenario 6-4
8-1 Comparison of Costs for Groundwater Treatment/Discharge Alternatives 8-5
9-1 Discharge Levels for Contaminants of Concern 9-8
9-2 Summary of Costs for Extraction System 9-12
9-3 Summary of Costs for Alternative T-7: Precipitation/UV-Oxidation/GAC/Re-lnjection ... 9-13
10-1 Identification of Action-Specific ARARs and To-Be-Considered Guidance 10-2
10-2 Identification of Chemical-Specific ARARs and To-Be-Considered Guidance 10-5
10-3 Identification of Location-Specific ARARs and To-Be-Considered Guidance 10-6
ix
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1.0 SITE NAME. LOCATION AND DESCRIPTION
Milan Army Ammunition Plant (MAAP) is located in western Tennessee, 5 miles east of Milan,
Tennessee, and 28 miles north of Jackson, Tennessee (Figure 1-1). MAAP is a government-owned,
contractor-operated installation with Martin Marietta Ordnance Systems, Inc., as the operating contractor.
The facility was constructed in 1941 to produce and store fuzes, boosters, and small- and large-caliber
ammunition. At present, the facility comprises 22,436 acres.
MAAP lies within the coastal plain province of the Mississippi Embayment, west of the Western
Valley of the Tennessee River and east of the Mississippi River Valley. The topography of MAAP and
surrounding area is gently rolling to flat. It slopes regionally westward and contains numerous small
streams, creeks, and drainage ditches. The elevation of the plant varies from a high of approximately 590
feet above mean sea level (ft-msl) on the south side to a low of approximately 320 ft-msl on the north
boundary of the plant.
Numerous perennial and ephemeral surface water features occur within the installation and flow
to the north-northwest. The entire facility, except for its extreme southern portion, drains via small creeks
and ditches to the Rutherford Fork of the Obion River. The northern portions of MAAP contain several
well-developed, ephemeral, natural drainage bodies that join the Rutherford Fork along the northern
boundary of the installation. The two parent streams, the Forked Deer River and the Obion River, empty
into the Mississippi River about 60 miles west of MAAP.
Qroundwater is a primary source of potable and non-potable water in this area of Tennessee.
At MAAP, the Memphis Sand of the Claibome Group is the major aquifer, and is thick, laterally continuous,
and highly transmissive. Groundwater flow in the MAAP area is generally to the west, in the direction of
the regional dip of these sands, and also trends northerly because of the topographic influence. On a
general scale, there are no abrupt hydrologic boundaries in the aquifer. The formation is recognized as
sand with clay lenses and clay-rich zones.
The facility is located in a rural area, with agriculture being a primary land use. There are
scattered residences to the north and east of the facility boundary. North of the facility, the nearest
residences are located north of the Rutherford Fork, which probably acts as a shallow groundwater divide.
These residences are downgradient from the O-LJne Ponds area and are approximately 1.5 miles from the
O-LJne Ponds. On the east side of the facility, residences are located along the facility property line.
These homeowners are not at risk from the contamination emanating from the O-LJne Ponds because they
are cross-gradient and upgradient from the O-LJrie Ponds. Within the facility, the Army performs regular
monitoring of the potable water production wells to ensure that no contamination is present Therefore,
under current land use conditions, humans are not exposed to the contaminated groundwater in the O-
Line Ponds area. Future land use scenarios may present potential human health risks if the property is
developed for residential use.
Of the thirteen process areas active by the end of World War II, only seven lines are in use today.
As shown in Figure 1-2, the active process areas are distributed through the northern half of the facility.
O-LJne is located in the north central portion of MAAP. Immediately north of O-LJne are the O-LJne Ponds
(now closed), which historically received wastewater from the operations conducted at O-LJne.
Contaminated groundwater that is addressed in this ROD emanates from the O-LJne Ponds area, which
is described in more detail in the next section.
1-1
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MISSISSIPPI
ALABAMA
Figure 1-1
Location of MAAP In Western Tennessee
1-2
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3979-
3978-
3977-
3976-
3975-
J2 3974 -
32
"3
3973 -
^M
Z)
3972-
3971 -
3970-
3969-
3968-
3967-
3966-
3965-
3964
Univ. of T«nn.
AgnculftjrM
R«s»«/cn ATM
E3 National Guard Area
Q Operating Units of MAAP
O Private Ownership
341 342 343 344 345 346 347 348 349 350
UTM Coordinates (kilometers)
351 352
Figure 1-2
Active Process Areas Within MAAP
1-3
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2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
The O-Line area (Figure 2-1) at MAAP was built as part of the initial plant construction activity in
1941, and has operated since 1942 as an ordnance demilitarization facility. From the start, the major
function of the line has been to remove explosives from bombs and projectiles by injecting a high-
pressure stream of hot water and steam into the steel shell of the munitions. The types of explosives
handled in the facility include 2,4,6-trinitrotoluene (TNT) and RDX.
Wastewater contaminated with explosives was discharged from the 0-Line washout operations
through a series of baffled concrete sumps where cooling caused significant amounts of explosives to
precipitate out of the waste stream. Effluent from the sumps was initially discharged to an open ditch
which ran through the O-LJne area In 1942, 11 individual surface impoundments were excavated to
receive the O-Line effluent before discharge to the open ditch. The ponds (Figure 2-2) reportedly were
excavated into native soil and the excavated material was used to form the pond dikes.
. The ponds were 3-5 feet deep, had a total capacity of 5.5 million gallons, and covered an area
of about 280,000 square feet (USATHAMA, 1982a). The ponds were interconnected with a series of
spillways, open ditches, and distribution boxes allowing several pond configurations to be used in series.
Effluent from the last pond flowed through a bank of sawdust-filled tanks before discharge to Ditch B.
The drainage ditch that received effluent from the final pond discharged to the Rutherford Fork of the
Obion River which runs along the northern boundary of MAAP as shown in Figure 2-1.
In 1978, USATHAMA conducted an Installation Assessment of MAAP (USATHAMA, 1978), which
consisted of a records search and interviews with employees. It was reported in this document that
between 300 to 500 pounds of explosives could be washed out in an 8-hour shift, and that many types
of explosive materials were handled in this area At the time of the survey, all of the wastewater ponds
were full and signs of overflow were obvious. The overflow entered the open ditch near O-LJne.
Also in 1978, the U.S. Army Environmental Hygiene Agency's (USAEHA) water well sampling
program (USAEHA, 1978) revealed that three of MAAP's 11 water supply wells were contaminated with
explosive constituents. The affected wells were near a number of production areas, including O-LJne.
MAAP facility personnel ceased using the O-LJne Ponds since the ponds were determined to be
one of the most likely sources of groundwater contamination. As a result, the O-LJne operation was
placed in a standby status in December 1978, and effluent has not been discharged to the ponds since
that time. The impounded effluent remained in the ponds until 1981, when the supernatant was pumped
out and treated in a newly constructed pink water treatment facility (PWTF), consisting primarily of carbon
adsorption units and fabric filtration units. The effluent from the PWTF was discharged to the open ditch
under the facility's NPDES permit A PVC liner was placed on top of the pond sediments in 1981 and the
liner was filled with fresh water to stabilize it.
MAAP subsequently prepared and submitted a closure plan for the pond site (USATHAMA,
1982b). The closure plan was approved by the Tennessee Department of Health and the Environment
0"DHE) and implemented in 1984. The closure plan called for the construction of a multilayered cover
system for the ponds. The ponds were filled with clean inorganic fill, and two clay layers were placed on
top and compacted. A gravel drainage layer was placed between the clay layers. Topsoil was placed
on top of the upper clay layer and a vegetative cover was then established.
2-1
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Figure 2-1
O-Une and O-Une Ponds Location
2-2
-------
Feet
Wastewater
from O-Line
Figure 2-2
Schematic of O-Une Ponds During Use
2-3
-------
The rationale for taking the ponds out of service and placing a liner on top of the contaminated
soil was to decrease hydraulic loading on the source. The cap was designed to further minimize hydraulic
loading on the contamination source by providing a multilayered cover system.
However, in May 1984, because of the level of contamination in the groundwater, the facility was
proposed for listing on the National Priorities List (NPL). The NPL is EPA's list of hazardous waste sites
that present the greatest potential threat to human health and the environment if remediation does not
occur. Final listing on the NPL took place in August, 1987.
In 1990-1991, the U.S. Army Toxic and Hazardous Materials Agency (USATHAMA) conducted a
Remedial Investigation (Rl) at MAAP (USATHAMA, 1991). The Rl was conducted to identify the type,
concentration, and extent of contamination. Some of the results of the Rl are as follows:
The levels of explosives in groundwater samples collected near the ponds are very high
(more than 10,000 times higher than EPA's health advisory levels). The concentrations
of explosives in groundwater decrease as the distance from the O-LJne Ponds increases.
Available data indicate that the area of groundwater contamination associated with the
ponds themselves is approximately 2,500 feet in length and possibly as much as 1,500
feet wide.
The vertical extent of the groundwater contamination appears to extend from the water
table to a maximum depth of 170 feet below the ground surface.
It is likely that other sources of contamination exist downgradient of the ponds which have
contributed to the total area of groundwater contamination. These areas are being
addressed in additional studies.
The contaminants of concern include explosives such as 2,4,6-trinitrotoluene (TNT), 2,4-
dinitrotolueneand2,6-dinitrotoluene(DNT),RDX, HMX, nitrobenzene, 1,3,5-trinrtrobenzene
(TNB), and 1,3-dinitrobenzene (DNB).
In order to respond as rapidly as possible to the potential threat posed by contaminated
groundwater in the vicinity of the O-LJne Ponds, the Army has elected to separate the O-Line Ponds area
from the remainder of the facility and to address remediation of this unit while further investigation of other
units continues. In 1991-1992, a Focused Feasibility Study (FFS) of the O-Line Ponds area groundwater
(OU 1) was conducted (USATHAMA, 1992a). The purpose of the FFS was to identify remedial
technologies that are capable, singly or in combination, of mitigating the risks posed by the Operable Unit.
Because several of the most promising technologies identified in the FFS have not been widely deployed,
limited data are available to fully assess their potential effectiveness for the Operable Unit-specific
conditions and contaminants. To fill this data gap, treatability studies were performed in 1992 to further
evaluate the effectiveness, implementability, and cost of the most promising technologies.
Based on the information gathered and presented in the FFS report (and on the results of the
treatability studies), the Army selected a preferred remedy for the O-LJne Ponds area groundwater. The
rationale behind the remedy was presented to the public in a Proposed Plan (USATHAMA, 1992b).
2-4
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3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
The Rl report for MAAP was released to the public in December 1991 and presented at a public
meeting held during the same month. The FFS report and Proposed Plan were released to the public in
July 1992. All of these documents are available in both the Administrative Record and the information
repository maintained at the Army Chief Engineer's Office at MAAP and the Mildred G. Fields Library,
Milan, TN. The notice of availability of these documents was published in The Mirror Exchange on June
24, 1992 and The Jackson Sun on June 27, 1992.
A 45-day public comment period was held from July 1, 1992 through August 15, 1992. In
addition, a public meeting was held on July 16,1992. At this meeting, representatives from MAAP, EPA
and TDEC answered questions about problems at the site and the remedial alternatives under
consideration. Comments and responses from the July 16,1992 Public Meeting have been captured in
the meeting transcription, which is included in the Responsiveness Summary (Appendix A). No written
comments were received during the comment period.
This decision document presents the selected remedial action for the 0-Line Ponds Area, Milan
Army Ammunition Plant, Milan, TN, chosen in accordance with CERCLA, as amended by SARA, and, to
the extent practicable, the National Contingency Plan. In addition, this decision incorporates the findings
of treatabilrty studies conducted to determine the effectiveness of the treatment technologies selected as
a result of the FFS. The decision for this site is based on the Administrative Record.
3-1
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4.0 SCOPE AND ROLE OF OPERABLE UNIT OR RESPONSE ACTION
Past disposal practices at the 0-Line Ponds contaminated soil and groundwater near the former
ponds. The goal of the overall cleanup activities at MAAP is to reduce the levels of contaminants to below
health-based concentrations, such that no adverse health effects will result from future use of the facility.
Presently, more information is available concerning the nature and extent of groundwater contamination
than is known about soil, surface water, and sediment contamination within the O-LJne Ponds area.
Because contaminated groundwater potentially poses an unacceptably high level of risk to human health,
this environmental medium has been separated from the others. This separation of environmental media
into Operable Units (OU) allows the Army to begin groundwater cleanup prior to full assessment of the
entire NPL site.
An Operable Unit (OU) is defined by the National Oil and Hazardous Substances Pollution
Contingency Plan (40 CFR 300.5) as a discrete action which is an incremental step towards
comprehensively mitigating site problems. The Operable Units for the NPL site at MAAP have been
defined as follows:
OU 1: Contaminated groundwater beneath and immediately downgradient from the
former ponds which has been contaminated by past disposal practices at the
ponds.
OU 2: Contaminated soils beneath and around the former ponds and surface water and
sediment in the drainage ditch that flows along the east and north sides of the
ponds, which may have become contaminated as a result of past disposal
practices.
OU 14: Soil and water media in the area downgradient (to the north and northwest) of
OU 1 and OU 2, including Line K.
This Interim Action ROD applies to OU 1. OU 2 and OU 14 require additional investigation and will be
handled as separate actions. A final action ROD will be prepared to comprehensively address OU 1, OU
2, and OU 14, which make up the NPL site.
OU 1 consists of groundwater that has been contaminated by explosives compounds that seeped
from the ponds during past waste disposal operations. The primary contaminants in groundwater are
HMX, RDX, 2,4,6-TNT, 1,3,5-TNB, 2,4-DNT, 2,6-DNT, 1,3-DNB, and nitrobenzene.
Because drinking water wells are not located in the area of contaminated groundwater, there is
currently no risk posed to facility workers or area residents by the Operable Unit However, the baseline
risk assessment conducted as part of the FFS (USATHAMA, 1992a) indicates that the explosives
contamination in groundwater may pose a threat to human health should the area be developed for
residential use in the future. Contaminant migration toward the installation boundary is projected to lead
to an unacceptable health risk level for off-post residential use of groundwater.
The clean-up objectives for OU 1 are to extract and treat contaminated groundwater to prevent
current or future exposure to explosive compounds. The overall strategy consists of the following three
steps:
4-1
-------
. Contaminated groundwater will be pumped out of the aquifer;
Extracted groundwater will be treated with a combination of metals and explosives
treatment technologies; and
Treated groundwater will be safely disposed; possible methods include re-injection or
discharge to surface water.
In pursuit of the overall goal of reducing the levels of contaminants to health-based levels, UV-
oxidation, an innovative technology, will be used to remove explosives compounds from extracted
groundwater. This technology was selected because of uncertainties regarding the ability of more
commonly-used technologies in reducing the concentrations of contaminants to the health-based levels.
UV-oxidation has not previously been applied in full-scale systems to remove these contaminants;
however, it has the potential to meet the stringent criteria
The Army has elected to perform this phase of groundwater cleanup under an Interim Record of
Decision (ROD), which allows for treatment system design, construction, operation (using the discharge
limits listed in Section 9.0, which for several explosives compounds are higher than health-based
concentrations), and performance evaluation for a set period of time. At the end of the performance
evaluation period, the treatment system capabilities and discharge levels will be reevaluated. If the health-
based levels for the contaminants of concern have changed in the interim, these new values will become
the treatment goals. A final remedy will be selected which satisfies all health based clean-up levels or
provides technical data, consistent with CERCLA and the National Contingency Plan, which justifies
alternative standards.'
The interim remedial action will greatly reduce the potential human health risks associated with
the hypothetical ingestion, dermal contact, or inhalation of contaminants in groundwater. Treatment of
the groundwater will destroy and remove explosives, thereby reducing the toxicity and volume of
contaminants in groundwater. In addition, groundwater extraction will serve to eliminate the migration of
contaminated groundwater to off-site areas.
Because this interim remedial action requires that the further migration of contaminated
groundwater within the O-LJne Ponds area be stopped, and the concentrations of contaminants in
groundwater be greatly reduced, it is consistent with any planned future actions.
4-2
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5.0 SITE CHARACTERISTICS
This section provides an overview of the 0-Line Ponds characteristics related to OU 1 including
a summary of the hydrogeologic setting, the nature and extent of groundwater contamination, potential
routes of contaminant migration and exposure, and a summary of human health and ecological risks. The
information presented in this section was summarized from the Rl (USATHAMA, 1991) and FFS
(USATHAMA, 1992a).
5.1 HYDROGEOLOGIC SETTING
Sands in the Claibome and Wilcox Group are the principal sources of groundwater in western
Tennessee. The major aquifer at MAAP occurs within the Memphis Sand of the Claibome Group, which
are deposits of Tertiary age in the Gulf Coastal Plain of western Tennessee. The total depth of this
unconfined aquifer is on the order of 250 feet in the areas of interest at MAAP, and the major controls on
groundwater movement are the dip of the sediments, surface topography, and surface recharge and
discharge patterns. Groundwater flow in the MAAP area is generally to the west, in the direction of
regional dip of these sands, and also trends northerly because of the topographic influence. The gradient
of the sands is estimated to be about 20 feet/mile to the northwest. On a general scale, there are no
abrupt hydrologic boundaries in the aquifer. The sandy formation contains local clay lenses and clay rich
zones which may locally alter vertical groundwater flow, and stratification of the sediments also tends to
make vertical conductivities lower than horizontal conductivities.
Groundwater flows in a direction perpendicular to groundwater contour lines at a rate determined
by the hydraulic gradient, i =£» hA L, (i.e., the hydraulic head over a given distance); the specific yield of
the aquifer; and the hydraulic conductivity (estimated from aquifer test results to be approximately 27 feet
per day). The pathlines shown in Figure 5-1 illustrate the general flow directions for groundwater beneath
MAAP. The horizontal hydraulic gradient is very low at MAAP, resulting in a low velocity for groundwater
flow. From water level data, the horizontal hydraulic gradient is estimated as 0.0015 ft/ft. For an aquifer
specific yield of 20% (a representative value for this aquifer material), the average groundwater flow
velocity is calculated to be 0.20 ft/day. Small variations in flow velocity are expected for various areas of
the facility, depending on variations in the controlling factors.
In the vicinity of the O-LJne Ponds, groundwater is recharged by precipitation infiltration in the
higher-elevation southern portion of the facility, arid infiltration is enhanced through the floor of the
drainage ditches in the area Partial discharge of groundwater to the Rutherford Fork of the Obion River
is indicated by considering the relationships between elevations of the water table, the variation of
hydraulic potential with depth, and the elevation of the stream surface.
5.2 CONTAMINATION ASSESSMENT
The results of the Rl (USATHAMA, 1991) indicate the principal sources of explosives contamination
in groundwater at MAAP are the O-LJne Ponds and the drainage ditches from this area The groundwater
in this area of the installation contains organic contaminants (the explosives compounds 2,4,6-TNT, HMX,
RDX, nitrobenzene, 2,4-DNT, 2,6-DNT, 1,3,5-TNB, and 1,3-DNB). Of the contaminants found in the near
vicinity of the O-Line Ponds, 2,4,6-TNT, RDX, and the DNT isomers are present in the highest
concentrations and/or pose the greatest risk. 2,4-DNT and 2,6-DNT are Class B2 carcinogens (meaning
they are probable human carcinogens based on sufficient data from animal studies and inadequate data
from human studies) and RDX and 2,4,6-TNT are designated as Class C carcinogens (they are possible
human carcinogens based on inadequate evidence from human studies and limited evidence from animal
5-1
-------
GRADIENT
0.0015 ft/ft
LEGEND
STREAM/DRAINAGE
PROPERTY LINE
MONITORING WELL
GROUNDVATER CONTOUR
APPARENT SURVEY ERROR
i GRADIENT
0.0012 ft/ft
i
GRADIENT
0.0019 ft/ft
Figure 5-1
Groundwater Flow Direction* and Horizontal Hydraulic Gradients
5-2
-------
studies). Section 6.0 of this Record of Decision provides more detail concerning the baseline risks and
potential routes of human and environmental exposure of these contaminants.
5.2.1 Summary of Remedial Investigation Results
The groundwater data collected during the Rl show that explosives-contaminated groundwater
near the O-LJne Ponds is migrating slowly toward the north. Figures 5-2 and 5-3 show the concentrations
of RDX and 2,4,6-TNT, respectively, detected in the wells downgradient and cross-gradient of the O-Line
Ponds area during the Rl field investigation. Concentration plots for the other explosives-related
contaminants exhibit this same general configuration, but are smaller in areal extent. High concentrations
in the southern portion of the contaminated zone are attributed to inputs from the O-Line Ponds, and the
extended areas exhibiting lower concentrations in the northern portion of the contaminated zone are
attributed to inputs from the drainage ditches. The action under consideration addresses only the
groundwater in the near vicinity of the O-Line Ponds; therefore, only the southern portion of the
contaminated zone shown in Figures 5-2 and 5-3 are of interest. (The remaining contamination arising
from the drainage ditches will be addressed in a separate action).
The movement of contamination in groundwater from the vicinity of the O-Line Ponds toward the
north is explained by advective-dispersive processes. Mechanical dispersion appears to be the dominant
process causing lateral spread of contamination.
5.2.2 Summary of Post-RI Sampling and Analysis
In January-February of 1992, additional field work was conducted to further evaluate the nature
and extent of contamination at the O-Line Ponds area Data from chemical analysis of groundwater
samples indicate that the levels of explosive compounds in the shallow aquifer near the O-Line Ponds
have decreased from the time that the Rl sampling occurred; the reason for this is not known. The data
further show that the only detectable organic compounds in groundwater immediately downgradient of
the capped area are explosives residues, and inorganic constituents (metals) are only of concern in
regard to possible interference with organic treatment processes.
5.2.3 Extent of Groundwater Contamination
The chemical data collected during the Rl show that shallow groundwater in the zone immediately
downgradient of the O-LJne Ponds (e.g., from wells MI001 and MI058) had very high levels of explosives.
Groundwater from an intermediate depth in the aquifer (e.g., from wells MI057 and MI075) show much
lower concentrations of explosives, indicating that the levels of contaminants falls off rapidly with depth.
However, explosives were detected above health advisories in well MI075, which is located directly
downgradient of the O-LJne Ponds, at a depth of 170 feet (the depth to groundwater is approximately 45
feet in this area). Based on the configuration of contaminated zones developed during the Rl and the
depth at which contamination has been detected, it is estimated that the zone of contaminated
groundwater comprising this operable unit has approximate dimensions of 1,500 feet in width, 2,500 feet
in length and 125 feet in depth. Using these dimensions and a soil porosity of 20%, it is estimated that
approximately 1 X 108 gallons of water may be contaminated to an extent such that extraction and
treatment should be considered.
5-3
-------
D' LINE
PONDS
(CLOSED
349000
330000
Figure 5-2
RDX Concentrations Downgradlent of the O-Une Ponds Area
(Detected In 1990)
5-4
-------
Figure 5-3
2,4,6-TNT Concentrations Oowngradlent of the O-Une Ponds Area
(Detected In 1990)
5-5
-------
6.0 SUMMARY OF SITE RISKS
Risk assessment consists of the evaluation of the types and levels of contaminants present within
the Operable Unit, the pathways by which receptors could potentially be exposed to these contaminants,
and the toxicity and/or carcinogenicfty of the contaminants. A quantitative estimate of the potential for
adverse health effects to occur in the future can be constructed from these data In estimating these
risks, the assumption was made that no remedial action would be taken to address contamination within
the Operable Unit; the resulting analysis is referred to as a baseline risk assessment. The main focus of
this baseline risk assessment is to evaluate potential risks associated with the use of, and exposure to,
untreated groundwater immediately adjacent to the O-LJne Ponds (OU 1).
As discussed in Section 1.0, there are scattered residences to the north and east of the facility
boundary. Downgradient of the O-LJne Ponds area, the nearest residences are located north of the
Rutherford Fork and at a distance of approximately 1.5 miles from the O-LJne Ponds. Homeowners on
the east side of the facility are not at risk from the contamination emanating from the O-LJne Ponds
because they are cross-gradient and upgradient from the O-LJne Ponds. Within the facility, the Army
performs regular monitoring of the potable water production wells to ensure that no contamination is
present. Therefore, under current conditions, humans are not exposed to the contaminated groundwater
in the O-LJne Ponds area
Although MAAP is a currently operating government facility which is not scheduled for realignment
under the Base Closure and Realignment Act, the most stringent possible future land use scenario was
used in estimating the risks. This was done to ensure that the potential risks would not be
underestimated. The most stringent future land-use conditions consist of residential development of the
O-LJne Ponds area Under these conditions, the residents living at the O-LJne Ponds would be exposed
to contaminated groundwater via ingestion, which is the exposure pathway that poses the greatest threat
to human health.
Homeowners in this area of western Tennessee tend not to install drinking water wells deeper than
necessary to obtain sufficient quantities of water. The high permeability of the Memphis Sand aquifer
results in adequate well yield even at shallow depths within the aquifer. Therefore, the assumption was
made in this baseline risk assessment that on-site residents would be exposed to levels of contaminants
immediately downgradient from the O-LJne Ponds and shallow within the aquifer. The two monitoring wells
corresponding to these conditions are MI001 and MI058.
To evaluate the risk posed by all organic and inorganic constituents within the shallow aquifer,
the wells were sampled in January 1992. These data present the most complete and up-to-date picture
of conditions immediately downgradient from the O-LJne Ponds; therefore, the baseline risk assessment
was performed using these analytical data
6.1 Chemicals Of Potential Concern
Chemicals of potential concern are those chemicals believed to be associated with past activities
at the O-LJne Ponds. Table 6-1 lists all of the chemical analytes detected in monitoring wells MI001 and
MI058 in January 1992. All of the listed analytes were used in estimating the potential risk; however, many
of the analytes are not considered chemicals of concern. The chemicals that are not of concern are those
inorganic analytes that are essential nutrients or were detected at levels well
6-1
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Table 6-1
CHEMICALS OF POTENTIAL CONCERN IN GROUNDUATER
IMMEDIATELY DOWNGRADIENT OF THE 0-LINE PONDS
(ug/L)
Well
MI001 (a)
Well
MI058 (a)
Organics (b):
* Carbon Disulfide (CS2)
* 1,3-Dinitrobenzene (13DNB)
* 2,4-Dinitrotoluene (240NT)
* 2,6-Dinitrotoluene (260NT)
* HMX (HMX)
* Nitrobenzene (N8)
2-Propanol (2-PROL)
* RDX (RDX)
1,1,2,2-Tetrachloroethane (TCLEA)
" 1,3,5-Trinitrobenzene (135TN8)
* 2,4.6-Trinitrotoluene (246TNT)
Inorganics:
9.00E+00
7.80E+01
6.60E+01
1.60E+01
1.20E+03
3.58E+01
NO
6.40E+03
ND (<1)
7.50E+02
6;50E+03
50E+00
.95E+01
1.80E+02
.OOE+01
1.10E+03
1.53E+01
7.00E+00
7.80E+03
2.67E+00
2.15E+03
1.55E+04
Aluminum (AL)
Barium (BA)
Calcium (CA)
Cyanide (CYN)
Iron (FE)
Lead (PB)
Magnesium (MG)
Manganese (MN)
Mercury (HG)
Potassium (K)
Sodium (NA)
Vanadium (V)
Zinc (ZN)
1.90E+03
2.37E+02
8.98E+03
1 .43E+01
1 .05E+03
1.25E*00
2.97E+03
5.96E+02
1 .OOE+00
1.71E+03
6.03E+05
8.75E*00
3.90E+01
9.61E+01
. 1 .09E+02
2.08E+04
4.08E+01
6.95E*01
ND <<1)
6.93E+03
1 .08E+03
ND (<0)
3.17E+03
6.05E+03
ND (<11)
3.70E+01
* = Selected as a chemical of potential concern,
ND = Not detected. Detection limit provided in parentheses.
(a) Concentrations reported in duplicate samples were averaged together.
(b) USATHAMA chemical codes are listed in parentheses.
6-2
-------
below hearth-based limits, and those organic compounds that are considered sampling or laboratory
artifacts. This is further discussed below.
Of the organic compounds selected as chemicals of potential concern, three were detected at the
highest concentrations in both monitoring wells MI001 and MI058: HMX (1,200 pg/L and 1,100 /jg/L,
respectively), RDX (6,400 /jg/L and 7,800 pg/L, respectively), and 2,4,6-TNT (6,500 //g/L and 1 5,500 pg/L,
respectively). 1,3,5-TNB was also present in significant quantities in well MI058. The other explosives
compounds were detected at levels less than 750 /jg/L and are also included in the risk assessment.
The organic compounds carbon disulfide, 2-propanol, and 1 , 1 ,2,2-tetrachloroethane were detected
at very low levels. 2-Propanol was used to decontaminate sampling equipment and is therefore
considered an artifact of the sampling activity. 1,1,2,2-Tetrachloroethane is a common solvent and may
be a laboratory artifact; the fact that it was detected in only one of the shallow wells makes this more
likely. These two chemicals have been retained in the risk assessment, but are not considered chemicals
of concern because of the likelihood that they were detected in error. Carbon disulfide was detected in
both shallow wells and is therefore considered a chemical of concern; however, as will be discussed in
Section 6.4, the concentration at which this contaminant was detected is too low to indicate potential
adverse health effects could occur through lifetime ingestion of groundwater.
Of the inorganic chemicals detected in monitoring wells MI001 and MI058, the six essential
nutrients (aluminum, calcium, iron, magnesium, potassium and sodium) were detected at the greatest
concentrations. Barium and manganese were also detected at significant concentrations in both wells
(109 to 237 /jg/L and 596 to 1,080 /jg/L, respectively). All other inorganic chemicals were detected at
levels less than 40.8 /jg/L
6.2 Exposure Assessment
This risk assessment focused solely on potential human health risks associated with ingestion of
untreated groundwater from monitoring wells MI001 and MI058. Persons using untreated groundwater
as a domestic water supply could be exposed to chemicals in groundwater via ingestion of drinking water.
However, under current land-use conditions, untreated groundwater is not used by residents or other
individuals; therefore, no complete exposure pathways exist. Under future land-use conditions, potential
exposures and risks associated with ingestion of groundwater have been evaluated to provide a risk-
based measure of the levels of contamination associated with the suspected source area
Chronic daily intakes (GDIs) are calculated for residential drinking water exposures using the
estimated exposure point concentrations presented in Table 6-2. A reasonable maximum exposure (RME)
case was evaluated in accordance with EPA guidance. It was assumed that chemical concentrations in
the monitoring wells would remain constant over the duration of the exposure period. GDIs were
estimated for groundwater ingestion using the equation and assumptions presented below:
BW* AT* Days
6-3
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CD
Table 6-2
POTENTIAL RISKS ASSOCIATED WITH INGESTION OF GROUNDUATER
BY FUTURE RESIDENTS UNDER THE RESIDENTIAL LAND USE SCENARIO (a)
Chemicals Exhibiting
Carcinogenic Effects (c)
Organics:
2,4-Dinitrotoluene (24DNT)
2,6-Dini trotoluene (260NT)
RDX (RDX)
1.1,2,2-Tetrachloroethane (TCLEA)
2,4,6-Trinitrotoluene (246TNT)
Total
Chemicals Exhibiting
Noncarcinogenic Effects (c)
Organics:
Carbon Oisulfide (CS2)
1,3-Dinitcobenzene (13DNB)
HMX (HMX)
Nitrobenzene (NB)
ROX (RDX)
1.1.2,2-Tetrachloroethane (TCLEA)
1,3.5-Trinitrobenzene (135TNB)
2.4.6-Trinitrotoluene (246TNT)
Inorganics:
Barium (BA)
Cyanide (CYN)
Manganese (MN)
Mercury (HG)
Vanadium (V)
Zinc (Zn)
Hazard Index
Well MI001
Chronic Daily
Intake (CDI)
(mg/kg-day)
1.1E-03
2.6E-04
1.0E-01
NA
1.1E-01
Chronic Dai ly
Intake (CDI)
(mg/kg-day)
3.4E-04
3.0E-03
4.6E-02
2.7E-03
2.4E-01
NA
2.8E-02
2.5E-01
9.0E-03
1.0E-03
2.3E-02
3.8E-OS
4.6E-04
1.5E-03
Well MI058
Chronic Dai ly
Intake (CDI)
(mg/kg-day)
2.9E-03
1.6E-04
1.3E-01
1.1E-04
2.5E-01
Chronic Dai ly
Intake (CDI)
(mg/kg-day)
1.3E-04
3.0E-03
4.2E-02
1.1E-03
3.0E-01
2.7E-04
8.2E-02
5.9E-01
4.2E-03
1.5E-03
4.1E-02
NA
NA
1.4E-03
Cancer Slope .
Factor
(mg/kg-day)- 1
6.8E-01
6.8E-01
1.1E-01
2E-01
3E-02
Reference Dose
(mg/kg-day)
[Uncertainty
Factor] (d)
1E-01 [100]
1E-04 (3,000]
SE-02 [1.000]
5E-04 [10,000]
3E-03 [100]
4.6E-04 [1,000]
5E-05 [10,000]
5E-04 [1,000]
7E-02 C3]
2E-02 [500]
1E-01 [1]
3E-04 [1,000]
7E-03 [100]
2E-01 [10]
Weight of
Evidence (b)
[82]
[B2]
[C]
[C]
[C]
Toxicological
Endpoint (e)
fetotoxicity
spleen
liver .
liver/kidney
prostate
liver, UBC
spleen
liver
> blood pressure
neurological
neurological
kidney
liver, kidney
anemia
Well MI001
Upper Bound
Excess Lifetime
Cancer Risk
7E-04
2E-04
1E-02
NA
3E-03
1E-02
Risk
CDI:RfD
Ratio
3E-03
3E+01
9E-01
5E+00
8E+01
NA
6E+02
5E+02
1E-01
5E-02
2E-01
1E-01
7E-02
7E-03
1E+03
Well Ml 058
Upper Bound
Excess Lifetime
Cancer Risk
2E-03
1E-04
1E-02
2E-05
8E-03
2E-02
Risk
CDI:RfD
Ratio
1E-03
3E+01
8E-01
2E+00
1E+02
6E-01
2E+03
1E+03
6E-02
8E-02
4E-01
NA
NA
7E-03
3E+03
NA = Not applicable. CDI not calculated because this chemical was not selected as a chemical of potential concern in this well.
(a) Risks are calculated for those chemicals of potential concern with toxiciy criteria.
(b) USEPA Height of Evidence for Carcinogenic Effects:
[B2] Probable human carconogen based on inadequate evidence from human studies and adequate evidence from animal studies;
[C] Possible human carcinogen based on limited evidence from animal studies in the absence of human studies.
(c) USATHAMA chemical codes are listed in parentheses.
(d) Uncertainty factors represent the amount of uncertainty in extrapolation from the available data.
(e) Toxological endpoints arc endpoints most likely given a chemical's toxic effects. RfDs are based on toxic effects
in the toxological endpoint. If an RfD were based on a study in uhich a toxological endpoint were not identified,
the endpoint listed is one. known to be affected by the particular chemical of concern.
-------
where
GDI. = chronic dajly intake (mg/kg-day),
Cw = chemical concentration in groundwater (mg/0,
IR = water ingestion rate (I/day),
EF = frequency of exposure (days/year),
ED = duration of exposure (years),
BW = average body weight (kg),
AT = averaging time (70 years for carcinogens, 30 years for noncarcinogens), and
Days = conversion factor (365 days/year).
Drinking water exposures are evaluated for a resident between the ages of 0 through 30. For
persons 0-30 years of age, a time-weighted average body weight of 48 kg (based on data in USEPA
1989d), and a drinking water rate of 1.9 liters/day are used as parameters for the reasonable maximum
exposure (RME) case. The drinking water consumption rate has been calculated assuming a
consumption rate of 1 liter/day for individuals up to 10 kg (approximately 3 years of age), and a rate of
2 liters/day for persons over 3 years of age. An exposure duration of 30 years, the upper-bound time at
one residence, is assumed for residents (USEPA 1991, 1989a).
GDIs for carcinogens and for noncarcinogens in groundwater at the O-Une Ponds are presented
in Table 6-2.
6.3 Toxictty Assessment
Quantitative risk assessment involves combining intakes for exposed populations with reference
doses (RfDs, defined as acceptable daily doses for noncarcinogens) or slope factors (for carcinogens)
to derive estimates of noncarcinogenic hazard, or excess lifetime cancer risks, of the potentially exposed
populations. Table 6-2 presents chronic oral health effects criteria (slope factors and RfDs) for the
chemicals of potential concern to be quantitatively evaluated in this assessment.
No oral health effects criteria are available for aluminum, calcium, iron, lead, magnesium,
potassium, 2-propanol and sodium; therefore, potential risks associated with ingestion of these chemicals
will not be quantitatively evaluated. Exclusion of these chemicals from the quantitative evaluation is not
expected to result in significant underestimates of risk. The essential nutrients (aluminum, calcium, iron,
magnesium, potassium, and sodium) are not likely to pose adverse health effects at the concentrations
present in groundwater within the O-LJne Ponds area
6.4 Risk Characterization
For carcinogens, potential risks are calculated as the product of the chronic daily intake (GDI) and
slope factors. Risks were compared to EPA's target risk range of 10"4 to 10"6. An excess lifetime cancer
risk of 10"6 indicates that an individual's risk of cancer, over a lifetime, is increased by one in a million due
to exposure to the carcinogen. For noncarcinogens, potential hazards are presented as the ratio of the
GDI to the reference dose (CDI:RfD), and the sum of the ratios is referred to as the hazard index. In
general, hazard indices that are less than one are not likely to be associated with adverse health effects,
and are therefore less likely to be of regulatory concern than hazard indices greater than one.
Carcinogenic and noncarcinogenic risks associated with the ingestion of untreated groundwater
from monitoring wells MI001 and MI058 by future residents are presented in Table 6-2. The estimated
upper bound excess lifetime cancer risks for ingestion of groundwater from MI001 is 1x10~2. This risk
6-5
-------
exceeds EPA's target risk range of 10"6 to 10"4 range for human health protectiveness, and is due
primarily to RDX and 2,4,6-TNT, although 2,4-DNT and 2,6-DNT also contributed to the elevated risks. -
The excess lifetime cancer risk for a future resident ingesting groundwater from MI058 is 2x10"2
as presented in Table 6-2, and this value also exceeds EPA's risk range for human health protectiveness.
The primary chemicals contributing to this risk are RDX, 2,4,6-TNT and 2,4-DNT. It is important to note
that RDX and 2,4,6-TNT are Class C carcinogens, and therefore their carcinogenic risks could be over-
estimated. The carcinogenic risks from such possible human carcinogens are based on inadequate
evidence from human studies and limited evidence from animal studies. Therefore, the carcinogenic risk
levels are calculated conservatively and could be over estimated. For noncarcinogenic chemicals, the
hazard index exceeded one for both MI001 (Hl= 1,000) and MI058 (Hl= 3,000) due to 1,3-DNB,
nitrobenzene, RDX, 1,3,5-TNB1 and 2,4,6-TNT.
The highest detected concentration of lead was 1.25 /jg/L in monitoring well MI001. This
concentration is less than the suggested EPA final 'clean-up* level of 15 pg/L for lead in groundwater
(USEPA 1989b). Groundwater concentrations of 15 /jg/L lead are considered protective by EPA (USEPA
I990a) and are likely to correlate with blood lead levels below 10 ug/L in roughly 99 percent of young
children who are not exposed to excessive lead paint hazards or heavily contaminated soils. Therefore,
the lead in groundwater is not likely to contribute to the overall risk to future residents.
6.5 FUTURE OFF-SITE HUMAN HEALTH RISKS
There are no current pathways whereby human health could be adversely affected from exposure
to the groundwater near the O-LJne Ponds. Therefore, the Rl focused on evaluating the potential future
risks associated with eventual migration of contaminated groundwater from the O-Une Ponds area to off-
post areas where exposures via residential use could occur. This future-exposure scenario was evaluated
using a groundwater model based on advective-dispersive flow to determine future concentrations in the
event that no control on migration or removal of contaminants is implemented. The model predicted that
many decades would be required before contamination from the O-Line Ponds area would reach the
facility boundary, but unacceptably high risks ultimately may be present if migration is allowed to continue
unabated. The results showed that the combined lifetime cancer risks from potential exposure to
groundwater at the facility boundary would exceed the 10"5 risk level, and the hazard indices for
noncarcinogenic health effects also would be excessive.
6.6 ECOLOGICAL IMPACTS
The Rl did not identify any unacceptable on-site ecological risks due to contaminated
groundwater. An evaluation of the ecological risks associated with contaminated soil, surface water, and
sediment in the vicinity of the O-LJne Ponds area is being performed as part of the FFS for OU 2. In
addition, any off-site ecological impacts will be addressed in the Ecological Risk Assessment for the entire
Milan Army Ammunition Plant, targeted for publication in 1994.
1The U.S. Army Biological Research and Development Laboratory is currently conducting sub-chronic
animal studies of the toxicity of this compound.
6-6
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6.7 BASELINE RISK ASSESSMENT SUMMARY
The following conclusions may be drawn from the baseline risk assessment:
Groundwater contamination associated with past use of the 0-LJne Ponds does not pose
any short-term risk to human health or the environment under current land use conditions
because groundwater in this area is not used as drinking water;
Human health impacts are possible, however, if the O-Line Ponds area is developed for
residential use and groundwater is used as a source of drinking water;
Carcinogenic risk under the future residential land use scenario is due principally to the
presence of high levels of explosive compounds in shallow groundwater immediately
downgradient of the O-Line Ponds;
Adverse health effects posed by noncarcinogens under the future residential land use
scenario are also due principally to explosive compounds;
The quantrtation of risk indicates that the inorganic analytes are not at levels high enough
to cause adverse health effects.
The baseline risk assessment indicates that groundwater quality in the O-Line Ponds area has
been impacted and that use of this groundwater, currently or into the foreseeable future, for drinking water
would result in significant human health risks. The removal of explosive compounds from groundwater
will reduce the overall carcinogenic and noncarcinogenic risks to acceptable levels.
This interim remedial action will stop the further migration of contaminated groundwater in the
immediate vicinity of the O-Line Ponds area through extraction of groundwater from the aquifer.
Groundwater extraction and treatment will greatly reduce the concentrations of the chemicals of concern.
Therefore, implementation of this interim remedial action will result in significant reduction of the risks
potentially posed by the Operable Unit. The goal of the final remedy for the site is to reduce the
concentrations of contaminants in groundwater to below health-based levels. The final action remedy will
ensure that treatment of groundwater will occur to the maximum extent practicable, consistent with
CERCLA and the National Contingency Plan.
Actual or threatened releases of hazardous substances from this site if not addressed by
implementing the response action selected in this ROD, may present a current or potential threat to public
health, welfare or the environment
6-7
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7.0 DESCRIPTION OF ALTERNATIVES
Groundwater remedial alternatives were developed for OU 1 to satisfy the following remediation
objectives:
Protect human health and the environment;
Reduce the levels of contaminants to concentrations such that off-site future groundwater
users will not be exposed to the contaminants above health-based levels;
Use permanent solutions and treatment technologies; and
Achieve a remedy in a cost-effective manner.
This section describes the extraction system and the treatment and discharge alternatives for
groundwater.
7.1 ALTERNATIVE T-1: NO ACTION
The NCP requires that the 'no action* alternative be evaluated at every site to establish a baseline
for comparison. Under this alternative, no remedial action would occur to prevent current or future
exposure to the groundwater contamination. Alternative T-1 does not have associated capital and
operation and maintenance costs, and will not require any time for implementation.
7.2 ALTERNATIVE T-2: LIMITED ACTION
Alternative T-2 consists of long-term monitoring, physical barriers, and administrative actions. The
limited action* alternative does not reduce the toxicity, mobility, or volume of contamination but would
reduce the probability of physical contact with contaminated media Institutional controls such as deed,
access and land use restrictions would be implemented to reduce physical contact with contaminated
groundwater. Public education programs would be designed to inform the workers and local residents
of the potential site dangers. In addition, emergency provisions would provide a plan of action in the
event of an accidental exposure or sudden increase in risks associated with the Operable Unit. Long-term
environmental monitoring will be conducted at the O-Line Ponds area as well as quarterly sampling for
target pollutants in groundwater and surface water. The data collected from the monitoring program will
be reviewed at a minimum of every five years as required by the NCP at all sites where hazardous
chemicals remain untreated.
The purpose of this alternative is to inform the public, provide a data base, and evaluate changes
in site conditions over time. Alternative T-2 has an estimated capital cost of $49,000 and annual operation
and maintenance costs of $171,000. Present worth is estimated at $2,678,000 for a thirty year period at
a five percent discount rate.
7.3 COMMON ELEMENTS IN TREATMENT ALTERNATIVES T-3 THROUGH T-8
The remaining groundwater treatment alternatives contain a number of common features. Except
for the 'No Action* and 'Limited Action" alternatives (Alternatives T-1 and T-2), all of the alternatives now
being considered for the Operable Unit include collection technologies, on-site treatment, and discharge.
7-1
-------
Collection technologies involve the removal of contaminated groundwater from the aquifer through use
of extraction wells. The extracted water will be piped to an on-site treatment system, through an
aboveground piping system. On-site treatment would consist of a combination of chemical and physical
treatment technologies. The treatment alternatives vary only in the combination of these chemical and
physical processes used to meet required treatment effectiveness and different discharge criteria.
7.3.1 interim Remedial Action Treatment System Goals
The goal of this interim remedial action is to reduce the human health risks posed by conditions
within the Operable Unit. This goal will be pursued by preventing future human exposure to contaminated
groundwater through the use of both active groundwater remediation (extraction, treatment, and
discharge) and institutional controls. .
To lower the potential carcinogenic and noncarcinogenic risks to acceptable levels within the area
of interest, the concentrations of explosives compounds must be reduced to extremely low levels (this is
further discussed in Section 9.0). At present, it is not known if any currently-available treatment
technologies are capable of achieving this level of efficiency on a consistent basis for the required high
flow rate and for this combination and concentration of contaminants. The FFS for this Operable Unit
identified the most promising technologies and both bench- and pilot-scale treatability studies have been
performed to evaluate the effectiveness of these technologies. -However, the technologies were tested
at relatively small scale and the impact of system scale-up on treatment plant efficiency is not known.
For this reason, the Army has elected to choose the most promising remedial technology and
apply it to the Operable Unit under this Interim Action ROD. At a minimum, the treatment system will be
operated such that health-based levels will not be exceeded at the facility boundary; off-site residents will
therefore be protected from the contaminants associated with the Operable Unit. At the same time,
institutional controls will preclude human exposure to the contaminated groundwater.
The treatment technologies introduced and described in this section were selected not only for
their ability to protect off-site users but also for their potential to reduce the on-site concentrations of
contaminants to health-based levels. The ARARs and To Be Considered (TBC) standards relevant to this
OU are described in Table 10-1 through 10-3. In addition, Federal Ambient Water Quality Criteria and
Tennessee Surface Water Standards are ARARs for Alternatives T-4, T-6, and T-8, which include
discharges to surface waters.
7.3.2 Extraction System
Each of Alternatives T-3 through T-8 make use of an extraction well system to remove
contaminated groundwater from the aquifer immediately downgradient of the O-Line Ponds area.
Continuous pumping from the extraction wells will also lower the water table in this area and reverse the
hydraulic gradient on the downgradient side. Further migration of the groundwater currently within the
contaminated area will therefore be prevented by this system.
Because of the large lateral and vertical extent of contamination within the area to be remediated,
multiple extraction wells will be needed. It was assumed in developing the extraction system cost estimate
that six 6-inch diameter wells will be installed to depths of 125 feet. Submersible pumps will be used to
pump water to ground level. The piping from the wells to the treatment plant will be corrosion-resistant
and heated to prevent freezing.
The extraction system has an estimated capital cost of $327,000 and annual operation and
maintenance costs of $16,000. Present worth is estimated at $573,000 for a thirty year period at a five
7-2
-------
percent discount rate. These costs must be added to the cost estimates for each treatment/discharge
alternative to arrive at a total system cost. .
7.3.3 Discharge Options
The two discharge options under consideration are re-injection into the aquifer and surface water
discharge. Alternatives T-3, T-5, and T-7 include re-injection as the discharge method. In these
alternatives, a series of injection wells will be installed upgradient of the former ponds. As treated water
is re-introduced into the aquifer, the hydraulic gradient between the injection wells and the extraction wells
will increase, and this will result in a higher rate of groundwater flow between the sets of wells. It is
anticipated that use of the re-injection discharge option (and resulting control over the hydraulic gradient)
will increase extraction system efficiency and shorten the amount of time needed to extract the
groundwater currently within the contaminated area Upgradient re-injection offers the additional
advantage of creating a closed-loop system. The potential for adverse environmental impacts to occur
is reduced because the treatment system effluent will not leave the Operable Unit.
Alternatives T-4, T-6, and T-8 include surface water discharge of the treatment system effluent.
Because of the high expected flow rate (possibly as high as 500 gallons per minute), it is expected that
this discharge method will consist of piping the treated water to the Rutherford Fork of the Obion River.
It is not expected that the on-site drainageways could safely handle both the large treatment plant output
and the runoff from precipitation events without significant modification. Discharge to the river offers the
additional advantage of providing a mixing zone for the effluent However, because the treated water will
continuously be added to the river, the potential exists for ecological impacts to occur.
7.3.4 Other Assumptions Used In the Cost Estimates
The volume of groundwater which requires remediation is estimated to be as large as 108 gallons.
The on-site treatment systems have a proposed flow rate of 500 gpm in order to reverse the groundwater
gradient. It has been estimated that the systems may have to operate for thirty years or more. Due to
the long period of treatment anticipated, extensive administrative oversight will be required to ensure the
proper operation and maintenance and overall performance of this alternative. Long-term monitoring of
influent and effluent concentrations, residual characteristics, and the effectiveness of the alternative will
be required. Five year reviews will also be required as part of the long-term monitoring program.
Institutional restrictions, public awareness programs, and emergency provisions similar to Alternative T-2
would be implemented.
Details of the treatment process would be determined in the Remedial Design phase through
engineering design and analysis and the competitive bidding process. Implementation of each treatment
alternative will require the construction of a treatment building and parking/staging area; building heating
and lighting; long-term influent and effluent and groundwater monitoring; and a five-year review of
Operable Unit conditions.
7.4 ALTERNATIVE T-3: UV-OXJDAT1ON/RE-INJECTION
Alternative T-3 uses ultraviolet (UV) -oxidation to reduce the concentrations of the organic
contaminants in the extracted groundwater. UV-oxidation is an emerging technology that uses ozone as
an oxidant and UV light to break down organic contaminants such as explosives. The UV light enhances
the reactivity of ozone by transforming these molecules into highly reactive hydroxyl radicals. These
powerful oxidants react with the contaminants in the water, cleaving the chemical bonds and breaking
down the organic contaminants into simpler molecules. When carried to completion, the end products
of the oxidation process are carbon dioxide, water, and inorganic oxidation products such as nitrates.
7-3
-------
In this system, the ozone is generated on-site using air and electricity; after use, it is catalyzed
into oxygen and vented from the system. To reduce the risks associated with storage and handling of
reagents, chemical oxidants will not be used in this system. No off-gases or treatment residuals requiring
disposal are generated by this process. Following treatment in the UV-oxidation chamber, the effluent
is discharged by re-injection wells back into the aquifer. Therefore, the potential environmental risks
associated with operation of this system are negligible.
This alternative is expected to reduce the levels of organic compounds to levels such that health-
based limits will not be exceeded at the facility boundary. However, this alternative does not remove
inorganic constituents from the groundwater. The results of the baseline risk assessment indicate that
the levels of inorganic analytes currently do not pose a threat to human health; however, fouling of the
pipingAreatment system may result if the groundwater is not treated to remove these inorganic analytes.
This could potentially lead to increased system maintenance costs. In addition, it is possible that the
levels of inorganic analytes in extracted groundwater could rise above health-based limits either due to
extraction from a more contaminated area or the addition of groundwater extracted from other Operable
Units. In this case, the treatment system must be modified to provide for treatment of inorganic analytes.
UV-oxidation has not previously been applied in a full-scale treatment system for these
contaminants. To assess the potential performance of this technology, the Army has performed bench-
and pilot-scale treatability studies of UV-oxidation using groundwater extracted from a highly contaminated
monitoring well immediately downgradient of the O-LJne Ponds. The results of these studies indicate that
significant reduction of the concentrations of explosives compounds can be achieved.
Alternative T-3 has an estimated capital cost of $4,216,000 and annual operation and maintenance
costs of $1,243,000. Present worth is estimated at $23,325,000 for a thirty year period at a five percent
discount rate.
7.5 ALTERNATIVE T-4: PRECIPITATION/UV-OXIDAT1ON/ION EXCHANGE/SURFACE WATER
DISCHARGE
This alternative incorporates physical and chemical processes to treat the groundwater to levels
acceptable for surface water discharge. As in Alternative T-3, UV-oxidation is used to reduce the
concentrations of the organic compounds. No treatment residuals are produced through the use of this
process.
To ensure that aquatic life will not be impacted by the treatment plant effluent, a series of metals
removal technologies are used. Electrochemical precipitation and ion exchange are two treatment
technologies which are capable of removing metals from water. Electrochemical precipitation involves the
removal of metallic compounds from solution by adsorption and co-precipitation with a ferric hydroxide
floe. These solids are eventually dewatered by compression and disposed after proper characterization.
If the levels of inorganic analytes in the water must be further reduced, the ion exchange process may
be used. Low levels of metals such as cadmium, iron and zinc, are captured in the resin and less toxic
ions such as hydrogen or sodium are released. Once the resin is exhausted, the ion exchange unit must
be replaced. In some cases, it is possible to recover the metals from the exhausted resin.
Although electrochemical precipitation is not a widely used technology, it employs a simple
process and is readily implementable. Both bench- and pilot-scale treatability studies were conducted
using groundwater extracted from a highly contaminated monitoring well located immediately
downgradient of the O-LJne Ponds area The results of these studies indicate that the technology is
capable of reducing the concentrations of inorganic analytes to very low levels.
7-4
-------
The reagents needed for the electrochemical precipitation process include sodium hydroxide and
hydrochloric acid for pH control, a polymer to aid in settling of precipitated solids, and hydrogen peroxide
to increase precipitation efficiency. These reagents must be shipped, stored, and handled properly to
minimize risks to workers and the environment. In addition, the process generates a filter cake consisting
of iron and the inorganics removed from the groundwater. Although the filter cake is not expected to be
a hazardous waste, it must still be handled and disposed as a solid waste.
The ion exchange technology is widely-applied and reliable. Chemical reagents are not needed
in this process. However, the exhausted resin must be handled and disposed.
This alternative relies on technologies that require chemical reagents and/or require proper
handling and disposal of treatment residuals. These treatment residuals are not expected to constitute
a hazardous waste but must be treated as solid waste. In addition, the treatment system effluent is
discharged directly to surface water. Therefore, low to moderate environmental risks are posed by this
alternative.
Alternative T-4 has an estimated capital cost of $6,030,000 and annual operation and maintenance
costs of $2,691,000. Present worth is estimated at $47,397,000 for a thirty year period at a five percent
discount rate.
7.6 ALTERNATIVE T-5: PRECIPITATION/GRANULAR ACTIVATED CARBON (GAC)/
RE-INJECTION
This alternative incorporates GAC to reduce the levels of explosives such that health-based levels
will not be exceeded at the facility boundary. GAC is a widely-applied and well-understood technology
for removal of organic compounds from water. This process relies on the physical adsorption of organic
molecules onto a porous carbon matrix containing active adsorption sites. The rate of adsorption is
compound-specific, and compounds that are less soluble in water are more likely to be adsorbed. The
explosives compounds are moderately soluble and therefore have a moderate affinity for carbon.
The facility currently uses GAC to treat all process water; therefore, performance data are available
to evaluate this technology for the Operable Unit-specific contaminants. However, the discharge levels
set for the facility treatment plants are much higher than the health-based limits for the explosives
compounds; therefore, it is not known if GAC is capable of achieving these extremely low levels. In
general, the removal efficiency of GAC is reduced at low contaminant concentrations, especially at high
flow rates. This is most likely due to channeling within the carbon beds.
Spent carbon loaded with explosives compounds cannot be regenerated (due to the low volatility
of the explosives compounds), cannot be efficiently regenerated, and therefore is typically disposed. The
spent carbon may constitute a hazardous waste and therefore must be handled in accordance with the
requirements of RCRA Subtitle C. Because explosives compounds would be highly concentrated on the
spent carbon, and because the weak forces holding the explosives molecules to the carbon are reversible,
mismanagement of the carbon may result in further human health risks and/or environmental damage.
The carbon usage rate for this alternative is estimated to range from 500 to 1,600 IDS of carbon per day.
Chemical reagents must be handled and stored on site for use in the precipitation system. This
alternative utilizes technologies that generate treatment residuals; namely, a large amount of spent carbon
and a small amount of filter cake containing iron and other inorganic analytes. The re-injection wells used
to discharge the treatment system effluent form a closed loop with the extraction wells. Therefore, the
environmental risks posed by this technology are expected to be low to moderate.'
7-5
-------
Under this alternative, the treated water would be discharged through re-injection wells back into
the aquifer.. .....
Alternative T-5 has an estimated capital cost of $3,376,000 and annual operation and maintenance
costs of $1,964,000. Present worth is estimated at $33,567,000 for a thirty year period at a five percent
discount rate.
7.7 ALTERNATIVE T-6: PRECIPITATION/GRANULAR ACTIVATED CARBON (GAC)/
ION EXCHANGE/SURFACE WATER DISCHARGE
This alternative is similar to Alternative T-5 except that it may incorporate additional inorganics
treatment in order to satisfy surface water discharge requirements. An ion exchange system may follow
the GAC treatment to ensure protection of aquatic life.
The electrochemical precipitation unit requires that chemical reagents be handled and stored on
site. Residuals generated through the implementation of this alternative are filter cake from the
electrochemical precipitation process, a large amount of spent carbon from the GAC units, and exhausted
resin from the ion exchange units. In addition, the treatment system effluent is discharged to surface
water. The potential environmental risks posed by this alternative are expected to be low to moderate.
Alternative T-6 has an estimated capital cost of $3,701,000 and annual operation and maintenance
costs of $3,163,000. Present worth is estimated at $52,324,000 for a thirty year period at a five percent
discount rate.
7.8 ALTERNATIVE T-7: PRECIPITATION/UV-OXIDATION/GAC/RE-INJECTION
This alternative incorporates both organic and inorganics treatment processes to ensure that
levels of contaminants at the facility boundary will not exceed health-based limits. Extracted groundwater
is pretreated using the electrochemical precipitation system described in Alternative T-4. Metals treatment
is implemented to prevent fouling within the piping or the GAC system which follows. Although the
concentrations of metals detected in groundwater are not at high enough levels to pose a threat to human
health, the implementation of this technology provides inorganics treatment should the levels of metals
in the influent increase. After the precipitation process, UV-oxidation is used to reduce the levels of
explosives compounds (see Alternative T-3). GAC (see Alternative T-5) is then used as a secondary
treatment step to further reduce the concentrations of organic compounds to levels that provide protection
of off-site residents. This second organic treatment step is used to treat any organic compounds which
were not completely oxidized in the UV-oxidation system and to increase the cost efficiency of the overall
system.
The bulk of the explosives compounds are expected to be destroyed through UV-oxidation.
Therefore, GAC will be used at a much lower rate through the implementation of this alternative than rates
estimated in Alternatives T-5 and T-6. The carbon usage rate for this system is estimated to be between
70 to 150 IDS per day; this is a reduction of 90% from the carbon usage rate estimated for Alternatives
T-5 and T-6.
This alternative requires the handling and storage of chemical reagents. The treatment residuals
generated from the implementation of this alternative are filter cake from the electrochemical precipitation
process and a relatively small amount of spent carbon from the GAC units. The re-injection wells used
to discharge the treatment system effluent form a closed loop with the extraction wells. Therefore, the
environmental risks posed by implementation of this alternative are expected to be low.
7-6
-------
Alternative T-7 has an estimated capital cost of $5,259,000 and annual operation and maintenance
costs of $1,413,000. .Present worth, is estimated at $26,980,000 for a thirty year period at a five percent
discount rate.
7.9 ALTERNATIVE T-8: PRECIPITATION/UV-OXIDATION/GAC/ION EXCHANGE/SURFACE
WATER DISCHARGE
This alternative is similar to Alternative T-7 in that it combines UV-oxidation and GAG to reduce
the levels of explosives compounds in water. Treatment through ion exchange may be needed to
supplement the electrochemical precipitation treatment of inorganics for discharge to surface water.
Chemical reagents must be handled and stored on site for the electrochemical precipitation unit.
The treatment residuals include filter cake from the precipitation system and exhausted resin from the ion
exchange system. In addition, the effluent is discharged to surface water. Therefore, the potential
environmental risks posed by implementation of this system are low to moderate.
Alternative T-8 has an estimated capital cost of $5,583,000 and annual operation and maintenance
costs of $2,611,000. Present worth is estimated at $45,720,000 for a thirty year period at a five percent
discount rate.
7-7
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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 the nine criteria used to assess remedial alternatives as outlined in Section 300.430 (e) of the
NCP. Each of the nine criteria are briefly described below. All of the alternatives which include active
treatment and discharge of groundwater (Alternatives T-3 through T-8) were evaluated to meet the
threshold criteria of protection of human health and the environment and compliance with ARARs.
However, each alternative meets the primary balancing criteria to different degrees. To aid in identifying
and assessing relative strengths and weaknesses of the different remedial alternatives, this section
provides a comparative analysis of alternatives. As previously discussed, the alternatives are as follows:
Alternative T-1, No Action;
Alternative T-2, Limited Action;
Alternative T-3, UV-Oxidation/Re-injection;
Alternative T-4, Precipitation/UV-Oxidation/lon Exchange/Surface Water Discharge;
Alternative T-5, Precipitation/GAC/Re-injection;
Alternative T-6, Precipitation/GAC/lon Exchange/Surface Water Discharge;
Alternative T-7, Precipitation/UV-Oxidation/GAC/Re-injection; and
Alternative T-8, Precipitation/UV-Oxidation/GAC/lon Exchange/Surface Water.Discharge.
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 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 and/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 Toxlctty, Mobility, or Volume through Treatment is the anticipated
performance of the treatment technologies employed in a remedy.
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 that may result during the construction and implementation period.
Implementabllity is the technical and administrative feasibility of a remedy, including the
availability of materials and services needed to implement the chosen solution.
8-1
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Cost includes both capital and operation and maintenance costs.
State Acceptance indicates whether, based on its review of the RI/FS Report and
Proposed Plan, the State concurs with, opposed, or has no comment on the preferred
alternative.
Community Acceptance assesses in the Record of Decision following a review of the
public comments received on the RI/FS Report and the Proposed Plan.
The NCP (Section 300.430 (f)) states that the first two criteria, protection of human health and the
environment and compliance with ARARs, are threshold criteria1 which must be met by the selected
remedial action. The next five criteria are 'primary balancing criteria", and the trade-offs within this group
must be balanced. The preferred alternative will be that alternative which is protective of human health
and the environment, is ARAR-compliant, and provides the best combination of primary balancing
attributes. The final two criteria, state and community acceptance are "modifying criteria" which are
evaluated following comment on the RI/FS reports and the Proposed Plan.
8.2 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
The six alternatives which incorporate groundwater treatment and discharge (Alternatives T-3
through T-8) provide protection of human health and the environment. When implemented with an
extraction system, the contaminated groundwater can be contained and removed from the ground for
treatment thereby eliminating the exposure pathway by which off-site residents may be exposed to
contaminants currently within the area defined by this Operable Unit. Although these alternatives may
not be capable of reducing the concentrations of contaminants to levels below health-based limits,
institutional controls will prevent contact with this groundwater, thereby eliminating the exposure pathway
within the facility boundary. Alternatives T-3 through T-8 prevent the future degradation of the condition
of the off-site groundwater due to contamination currently within this Operable Unit.
Alternative T-1, No Action, will not meet this criterion because no actions are taken to eliminate,
reduce or control exposure pathways. Because this alternative does not meet this threshold criterion of
protection of human health and the environment, it will not be considered further in the comparison of
alternatives. Alternative T-2, Limited Action, does provide some protection in that it limits access to, and
use of, the contaminated groundwater through institutional controls. However, these controls do not
permanently reduce access to contaminated groundwater.
8.3 COMPLIANCE WITH ARARS
Treatment alternatives T-3 through T-8 are capable of meeting either groundwater ARARs or
surface water ARARs; and with the exceptions described below and in Section 9.0, are capable of meeting
health-based limits (including EPA Health Advisories and Drinking Water Equivalency Levels established
by RfDs and slope factors). Alternatives T-3, T-5 and T-7 are capable of treating the contaminants present
to levels acceptable for re-injection (in compliance with groundwater ARARs). Alternatives T-4, T-6, and
T-8 incorporate additional treatment technologies to meet surface water ARARs. However, it cannot be
determined without additional performance data if any of the alternatives proposed for this remedial action
will remediate the groundwater within the facility boundary to the levels set by the EPA Health Advisories
for RDX, 2,4,6-TNT, 1,3-DNB, and by the RfD for 1,3,5-TNB.
The Limited Action alternative, Alternative T-2, does not provide any action to reduce the levels
of explosive compounds which are presently above the Health Advisories and other health-based levels.
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Over long periods of time, levels may decrease due to natural degradation and dilution. .In this case,
eventual compliance with ARARs may be achieved. However, the length of time before this occurs may
be extensive. Because this alternative does not meet this threshold requirement of compliance with
ARARs, it will not be considered further in the comparison of alternatives.
8.4 LONG-TERM EFFECTIVENESS AND PERMANENCE
Each of the remaining alternatives provide long-term effectiveness and permanence for this limited
scope action. Alternatives using UV-oxidation 0"-3. T-4, T-7 and T-8) are the most effective in the long-
term and the most permanent because, if properly designed and optimized, this process leaves no
residual waste. However, if complete oxidation is not achieved, intermediates could be formed which may
be toxic. Alternative T-3 uses UV-oxidation as the sole treatment process. This alternative has the
potential to be very effective in the long term and very permanent. In addition, UV-oxidation can easily
be adjusted to accommodate future fluctuations in groundwater contaminant levels. The processes used
in Alternative T-4 generate filter cake and exhausted resin from the additional inorganics treatment
(precipitation and ion exchange) implemented. These residuals must be disposed properly.
Residuals generation is more of a concern in the remaining alternatives which utilize GAG.
Alternative T-7 and T-8 utilize GAG as a polishing step and, therefore, generate a relatively small amount
of spent carbon. This polishing step ensures that intermediates which may be generated by the UV-
oxidation system are not discharged. Alternatives T-5 and T-6 use GAG alone for the removal of organic
compounds and, therefore, generate large quantities of spent carbon. Alternatives T-5 through T-8 also
generate residuals associated with the removal of inorganic analytes. All four of these alternatives
implement precipitation, which produces a filter cake, and Alternatives T-6 and T-8 implement ion
exchange, which generates exhausted resin. These residuals, in addition to the spent carbon, must be
disposed.
The effectiveness of Alternatives T-3 and T-7 has been evaluated in treatability tests. Both
alternatives are capable of reducing the level of explosives to those suitable for discharge. Although the
levels of inorganic analytes in the groundwater tested during the treatability tests were suitable for
groundwater discharge and required no treatment, future levels may be higher and inorganics treatment
may be necessary. Such treatment is not provided under Alternative T-3.
8.5 REDUCTION OF TOXICITY, MOBILITY OR VOLUME THROUGH TREATMENT
Alternatives T-3 through T-8, when used with an extraction alternative, all provide reduction of
toxicity, mobility or volume. Each of these alternatives has the potential to treat contaminants to below
the specified ARARs. Those alternatives which produce the smallest amount of residuals reduce the
toxicity and volume most permanently. Alternative T-3 produces the smallest amount of residuals.
Alternative T-4 produces a minimal amount of residuals which include filter cake from the precipitation unit
and exhausted resin from the ion exchange units.
Alternative T-7 generates a relatively small quantity of spent carbon as well as filter cake from the
precipitation process. Alternative T-8 generates exhausted ion exchange resin in addition to the residuals
generated by Alternative T-7. The largest quantities of residuals are produced by Alternative T-5 and T-6
which use GAG alone for organics treatment. Between these two, Alternative T-6 generates more
residuals than T-5 because ion exchange is also utilized.
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8.6 SHORT-TERM EFFECTIVENESS
Alternatives T-3 through T-8 would take approximately equal amounts of time and effort to
implement. All alternatives require that a treatment plant be built and that a discharge system such as
re-injection wells or a surface water discharge system be constructed. No additional risks are incurred
in the implementation of one alternative as compared to another.
8.7 IMPLEMENTABILITY
All of the alternatives are relatively easy to implement and readily available. However, some
alternatives are easier to implement over the long term due to their relatively low maintenance and
replacement requirements. Alternative T-3 may the easiest to implement because this system does not
require downtime for the replacement and disposal of spent carbon or ion exchange units; however,
untreated inorganics in the water may cause downtime due to system fouling. Alternative T-4 requires
frequent replacement of ion exchange units. Alternatives T-5 through T-8 all require replacement and
disposal of spent carbon. Alternatives T-5 and T-6 have higher carbon usage rates than T-7 and T-8 and
must be changed more frequently. In addition, T-6 and T-8 may require ion exchange unit replacement.
UV-oxidation processes used in Alternatives T-3, T-4, T-5 and T-6 are available through a limited
number of vendors. The electrochemical precipitation process used in Alternatives T-4 through T-8 is a
proprietary system. GAC used in Alternatives T-5 through T-8, and ion exchange systems used in
Alternatives T-4, T-6 and T-8, are offered by a large number of vendors.
8.8 COST
Table 8-1 provides a comparison of the costs of the remaining six alternatives.
In general, those alternatives implementing ion exchange (Alternatives T-4, T-6 and T-8) cost
significantly more than their respective alternatives which do not use ion exchange systems and
implement re-injection for discharge (Alternatives T-3, T-5, and T-7, respectively). The present worth of
these alternatives is approximately $20,000,000 more than systems implementing discharge by re-
injection. The additional costs are due to the frequent replacement of ion exchange units.
Of those alternatives developed for discharge to re-injection wells (Alternatives T-3, T-5 and T-7),
Alternative T-3 has the lowest present worth value. Costs are low due to the relatively simple treatment
scheme which uses only UV-oxidation. The present worth value for Alternative T-7 is only slightly higher
than that for Alternative T-3. Because UV-oxidation is used as primary treatment and GAC is used as a
polishing step in this alternative, the sizes of the systems are much smaller than units used in Alternatives
T-3 or T-5. This alternative also implements precipitation, which provides greater protection of human
health and the environment at a fractionally greater cost Alternative T-5 has the highest present worth
value due to the large quantities of carbon which must be replaced and disposed.
Alternatives developed for discharge to surface water are given in order of increasing present
worth cost as follows: Alternative T-8, Alternative T-4, and Alternative T-6. This order closely follows the
rationale given above for Alternative T-7, Alternative T-3 and Alternative T-5, respectively. However, due
to the implementation of precipitation in Alternative T-4 which was not implemented in Alternative T-3, the
costs for Alternative T-4 are slightly higher than those for Alternative T-8. Overall, costs for Alternatives
T-4, T-6, and T-8 are significantly higher due to the implementation of ion exchange.
8-4
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TABLE 8-1
COMPARISON OF COSTS FOR GROUNDWATER TREATMENT/DISCHARGE ALTERNATIVES
Alternative \
T-3: UV-Oxidation/Re-injection
T-4: Precipitation/UV-Oxidation/lon Exchange/Surface Water
Discharge
T-5: Precipitation/GAC/Re-injection
T-6: Precipitation/GAC/lon Exchange/Surface Water Discharge
T-7: Precipitation/UV-Oxidation/GAC/Re-injection
T-8: Precipitation/UV-Oxidation/GAC/lon Exchange/Surface Water
Discharge
Costs
Capital = $4,216,000
Annual = $1,243,000
Present Worth = $23,325,000
Capital = $6,030,000
Annual = $2,691,000
Present Worth = $47,397,000
Capital = $3,376,000
Annual = $1,964,000
Present Worth = $33,567,000
Capital = $3,701 ,000
Annual = $3,163,000
Present Worth = $52,324,000
Capital = $5,259,000
Annual = $1,413,000
Present Worth = $26,980,000
Capital = $5,583,000
Annual = $2,61 1,000
Present Worth = $45,720,000
8-5
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8.9 STATE ACCEPTANCE
The State of Tennessee concurs with the selection of Alternative T-7.
8.10 COMMUNITY ACCEPTANCE
Comments and responses from the July 16, 1992 Public Meeting have been captured in the
meeting transcription, which is included in the Responsiveness Summary (Appendix A). No written
comments were received during the comment period.
8.11 SUMMARY OF DETAILED EVALUATION
Based on the above, the following general conclusions may be drawn:
Treating groundwater to meet re-injection criteria for inorganic analytes (as in Alternatives
T-3, T-5 and T-7) is less difficult and less costly than meeting Ambient Water Quality
Criteria. In addition, re-injection would result in more efficient extraction of contaminated
groundwater due to enhanced gradient control. If upgradient re-injection is used, any
residuals would be captured by the extraction system and less monitoring may be
needed.
Use of both UV-oxidation (primary treatment) and GAG (polishing step), as in Alternatives
T-7 and T-8, appears to be preferable to using either process alone. The advantages of
the two-unit system are that intermediates which may result from incomplete oxidation
would be removed by the carbon and less system maintenance would be required.
Electrical costs are reduced significantly since the UV-oxidation system is not used to
reduce the level of organics to discharge levels. GAC usage is minimized since the
concentration of organics in the influent is greatly reduced through primary treatment.
It is conceivable that inorganics treatment may be needed in the future due to expansion
of the extraction system. Also, the use of precipitation during the pilot-scale treatabiltty
studies appeared to increase the efficiency of the UV-oxidation process. It is therefore
desirable to have the ability to treat both organics and inorganics.
Based on the comparative analysis given above, the selected remedy is Alternative T-7.
8-6
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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, with the concurrence of EPA and TDEC, has determined
that extraction of groundwater with treatment through the implementation of Alternative T-7 (precipitation,
UV-oxidation, GAC, and re-injection) is the most appropriate interim remedy for OU 1 at the O-LJne Ponds
Area at the Milan Army Ammunition Plant in Tennessee. Because of the large size and complexity of the
treatment system, its design may take between 12 and 24 months. This time estimate includes the
treatment system design and review, and preparation of bid packages. Following the design phase the
system construction will begin. This includes selection of contractors and equipment suppliers,
installation, and .start up. Although this section presents details of the selected remedy, some changes
may be made based on the remedial design and construction processes.
9.1 EXTRACTION SYSTEM
The mobility of the contaminants in the aquifer will be reduced by reversing and controlling the
groundwater gradient through the implementation of a groundwater extraction system. The specific
design of this system is dependent on modeling and aquifer testing results. Factors affecting the design
of the extraction system are the depth and thickness of the aquifer, the conductivity of the aquifer, and
the location of the contaminant plume. The highly conductive aquifer extends from the water table to a
depth of approximately 260 feet below ground surface. Explosives compounds have been detected at
Health Advisory levels at a depth of 170 feet below ground surface. In the plane parallel to the
groundwater flow direction, the contaminant plume is approximately 2,500 feet long. Perpendicular to the
flow direction, the apparent width is 1,500 ft Using these dimensions, a depth to the water table of 45
feet, and a porosity of 20%, the volume of water to be extracted is 1 x 108 gallons. Because even very
high extraction rates may produce only a relatively small cone of depression in high-permeability aquifers,
multiple wells will be needed to reverse the groundwater potential gradient over this large area It is
estimated that groundwater will be extracted from each extraction well at a rate of 50 to 100 gpm. For
purposes of arriving at an order-of-magnitude cost for the extraction system, a representative extraction
well system design is presented and evaluated.
This remedy will utilize approximately six extraction wells to achieve groundwater gradient reversal
and to extract contaminated groundwater. Large-diameter wells will be constructed of PVC. Submersible
pumps will pump water up to ground level where additional pumps will move water to the treatment site.
The total extraction rate is estimated to be 500 gpm. The extraction system will be constructed of
galvanized steel piping to provide corrosion resistance, and to prevent freezing, pipes will be heated with
steam injectors. The potential location of the extraction system is shown along with the proposed re-
injection system locations in Figure 9-1.
9.2 TREATMENT AND DISCHARGE SYSTEM: ALTERNATIVE T-7
In this remedy, shown schematically in Figure 9-2, electrochemical precipitation, UV-oxidation and
GAC are used in series. The predicted flow rate of the system is 500 gpm based on the extraction rate
needed to reverse the groundwater gradient. Groundwater is first pretreated using electrochemical
precipitation. The level of inorganics is reduced to levels acceptable for re-injection. UV-oxidation is then
used to remove the bulk of the organic compounds from water, and GAC is then used as a polishing step
to reduce the levels of explosives compounds to below discharge levels (discussed in more detail below).
A granular media filtration unit may be needed between the UV-oxidation and GAC
9-1
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ROUTE 104
(O
N
FORMER O-LINE PONDS
O Extraction Welt Location
D Re-Injection Well Location
__ Paved Road
- Railroad Tracks
- - - Groundwater Flow Direction
Proposed
Treatment Plant
Location
0-LINE
Figure 9-1
Location of Extraction and Re-Injection Well Systems
-------
(O
Groundwater
Extraction -
System
LEGENI
m Filter Backwash
Hydrogen Peroxide
UY
Neutralization Oxidation
1
1 ». Ozone
V / Granular 1 1 i 1
__ FUrtrochamlcal \ / Media 1 1 1 1
Precipitation A/ Filtration
/v ~~
s- , i -=i
Clanfier ^ I
t U --* Sludge to
~* niterlPress Dl8JMJ9ul
Filtrate \
):
»- Liquids
^ Solids
Granular . « .
Media Granular Granular
Filtration * Acnvarea * Acnvarea
Carbon Carbon
Unit l\ Unit 412
Treated
Water *
Re-Injection
FIGURE 9-2
MIUN ARMY AMMUNITION PUNT
ALTERNATIVE T-7
FLOW DIAGRAM
ICF KAISER MOO LEE HIGHJAT
ENSINEEHS fu$$\u
OMtic BBAX rrfdc* 04302
o«wi|E ..UdCENlr N»-
0* WM;' 092291O9
-------
units to ensure that any solid particles which have formed due to oxidation of metals do not enter the GAG
unit. Treated water is then re-injected upgradient of the extraction system to aid jn hydraulic gradient
control and provide additional flushing of the contaminated groundwater under the 6-Line Ponds. Each
part of the treatment system is described in detail below.
9.2.1 Electrochemical Precipitation
The electrochemical precipitation process is proposed for this Operable Unit because of its
relatively low maintenance demands, low residuals production, and low chemical reagent usage rate. This
process utilizes ferrous ions which coprecipitate heavy metals present in the groundwater. The ions are
generated by passing a direct current through a cell containing carbon steel electrodes. Because calcium
or ferric salt additives are not used to form a precipitate, the amount of sludge produced is reduced.
Precipitates which form settle out in a clarifier, are pumped to a filter press, are dewatered and then
disposed in the form of filter cake. The filter cake will be analyzed for hazardous waste characteristics
and disposed accordingly.
Treated water is filtered through a granular media filtration system to remove any additional
suspended solids prior to treatment with UV-oxidation. This procedure should provide adequate
pretreatment to eliminate solids which may hinder the UV-oxidation system. When suspended solids
begin to appear in the effluent beyond acceptable levels for feed to the UV-oxidation unit, the filter must
be backwashed to remove particles which have accumulated on the granular media. These solids will
be recirculated through the electrochemical precipitation process.
Electrochemical precipitation will reduce the level of heavy metals and other inorganics to below
the groundwater standards. In addition, this process removes inorganics which may cause unnecessary
loading on the GAG unit which follows.
9.2.2 UV-Oxldatlon
The selected remedy incorporates UV-oxidation in combination with GAC for the treatment of
groundwater contaminants to levels acceptable for re-injection into the aquifer. The bulk of the explosives
contamination in the groundwater will be destroyed through UV-oxidation. The specific treatment goals
of the UV-oxidation system is dependent on balancing the economic benefits gained in optimizing
operating conditions of the system.
After electrochemical precipitation and filtration, groundwater flows through a reactor which
contains a series of baffles holding several UV lamps. Ozone, a strong oxidant, is uniformly diffused from
the base of the reactor and is transformed into hydroxyl radicals, a reaction that is catalyzed by UV
radiation. Having a higher oxidation potential than ozone, these hydroxyl radicals react more readily with
the organic molecules. If complete oxidation is achieved, explosive contaminants are oxidized to carbon
dioxide, nitrogen, water and salts. Excess ozone is converted to oxygen using a nickel-based catalytic
converter prior to being vented to the atmosphere. Small chain aliphatic compounds may be formed as
intermediates if complete oxidation is not achieved, so the pH may require adjustment after treatment by
UV-oxidation. Results from treatability studies have shown that UV-oxidation is highly effective in reducing
explosive concentrations in groundwater.
9.2.3 Granular Activated Carbon
The GAG unit proposed for a 500 gpm system consists of 2 to 3 carbon units connected in series.
Each unit is capable of holding approximately 20,000 IDS of granular activated carbon (GAG). Because
UV-oxidation will remove most organic contaminants, and precipitation will remove inorganics, GAC will
be used at a much lower rate than the rates estimated for alternatives that rely solely on GAC for removal
9-4
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of explosives from groundwater. However, if complete oxidation is not achieved with the UV-oxidation
process, organic intermediates will also be adsorbed by the carbon and this usage rate may increase.
Exhausted GAC may be disposed through companies such as Solvent Recovery Corporation,
which presently accepts the GAC used at the PWTFs at MAAP. Because the carbon is used as fuel,
acceptance of the GAC and the costs for disposal are based on the BTU content of the carbon. The
exhausted carbon is disposed through a high temperature incineration process operated by this company.
9.2.4 Re-lnlectlon
Treated water will be re-injected into the aquifer upgradient of the ponds as shown in Figure 9-1.
The location and design of the re-injection well field are dependent on aquifer tests and modeling results.
Re-injection wells made of PVC will be screened along the entire depth of the aquifer (approximately 200
feet in length) to ensure adequate injection into the aquifer. Galvanized steel pipes will carry water from
the treatment site to the re-injection system.
9.3 PERFORMANCE MONITORING
A monitoring program shall be developed and implemented during the interim response action
to ensure that hydraulic control of the groundwater within OU I is maintained. Specifically, an inward and
upward gradient within the aquifer must exist to prevent further migration of the contaminated
groundwater from the Operable Unit. Information necessary for this determination includes:
horizontal and vertical gradients in the groundwater within OU I;
horizontal and vertical contaminant concentration gradients within OU I;
changes in contaminant concentration or distribution over time; and
effects of any modifications to the original interim response action.
To provide this information, the groundwater containment performance monitoring plan shall
include, at a minimum, the following: locations of new or existing monitoring wells for water quality
sampling; frequency of water quality sampling; analytical parameters (focusing on chemicals of concern)
and analytical methods to be employed; field sampling methods; specification of water level monitoring
locations, methods, and frequencies using new or existing wells; and methods for capture zone analysis.
9.3.1 Effluent Monitoring Program
A monitoring plan for the effluent from the treatment plant shall be developed and implemented
during the interim response action to ensure that control of the effluent is maintained prior to re-injection.
A monitoring program shall be developed during the design phase that provides periodic and/or
continuous information on the chemical constituency of the treatment plant effluent
To provide this information, the effluent monitoring program shall include, at a minimum, the
following: analysis of 24-hour composite samples at a frequency of twice a month for total suspended
solids, Target Analyte List metals, nitrates, nitrites, volatile organic compounds, and explosives compounds
(treatment plant influent concentrations will also be monitored at this frequency and for the above-listed
parameters); and continuous monitoring of pH and control within the limits of 5 and 7.
9-5
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9.4 TREATMENT SYSTEM PERFORMANCE EVALUATION
During the system start-up period, optimization studies shall be perfomed for reagent addition
rates, initial pH for the UV-oxidation step, and pH adjustment method. These data will be used to
establish cost-effective operating conditions and will also be used to complete a sensitivity analysis.
The interim remedy will be operated continuously for one year; during this time period, system
performance data will be collected and analyzed. In particular, the following information will be recorded
for evaluation:
. flow rate and influent concentrations;
variations in reagent addition rates and any corresponding changes in effluent
characteristics;
electricity usage; and
frequency of downtime for system maintenance or repair, and the nature of the repairs.
At the end of the one-year evaluation period, and after the toxicrty studies of 1,3,5-TNB have been
completed and the data analyzed, the Army will prepare the final remedy ROD for OU 1, OU 2, and OU
14. The system performance data will be summarized in this document. The final remedy ROD will also
contain the most up-to-date health-based criteria for the chemicals of concern. System perfomance will
be evaluated with respect to any changes in these levels from the health-based levels listed herein.
If the Army, EPA, and the State of Tennessee agree that a treatment system cannot reasonably
be expected to meet the health-based levels for the chemicals of concern on a consistent basis, then that
fact will be documented in the final remedy ROD. Achievable discharge levels will be determined from
the system perfomance data and other relevant information and will be entered into the final remedy ROD.
9.5 INSTITUTIONAL CONTROLS
The Army will ensure protection of on-site future users of groundwater. The active remediation
will be supplemented with institutional controls to prevent ingestion of contaminated groundwater
associated with OU I. These institutional controls will consist of the following:
The groundwater within OU I will not be used for potable purposes while the levels of
contaminants are higher than health-based levels; this will be ensured by Milan Army
Ammunition Plant Environmental Office review of all projects and leases involving well
installation and usage at the facility. Any well installed within the facility will be tested
prior to use.
In accordance with Army Regulation 200-1, entitled Environmental Protection and
Enhancement, the Army is required to perform preliminary assessment screening for the
subject parcel being excessed. This screening will evaluate potential use of the property,
identify any additional remedial activities, and/or place restrictions on the property to
protect the future landowners through a document entitled Statement of Condition. The
Army will implement the recommendations in the Statement of Condition prior to property
transfer.
9-6
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In addition, a continuing program of public awareness will be used to inform the public of the hazards
associated with contaminants that remain within the Operable Unit.
9.6 REMEDIATION GOALS
The goal of this interim action is to reduce the potential human health risks and restore the aquifer
to the extent practicable with the proposed technology. Active contaminant concentration reduction in
conjunction with natural attenuation in the aquifer will be used to assure that contaminants from this
Operable Unit do not affect future off-post drinking water. In addition, institutional controls will be used
to prevent on-site future usage of contaminated groundwater and to maintain public awareness of the
conditions at the Operable Unit.
The contaminants of concern for this interim remedial action are identified in the baseline risk
assessment conducted for this Operable Unit (Section 6.0). The list of chemicals of concern is comprised
of all organic contaminants detected in the groundwater samples except those which are probable
sampling or laboratory artifacts. In addition, all inorganic analytes detected in the groundwater samples
are included except those which are essential nutrients or which were detected at concentrations low
enough that no adverse health effects are predicted. Because nitrates are an oxidation product of the
explosives breakdown, this analyte is included with the chemicals of concern. The list of chemicals of
concern is provided in Table 9-1.
In developing contaminant discharge levels for the proposed remedial action, the following two
principal criteria have been applied:
the discharge levels must be protective of off-post human health; and
the discharge levels must be technically achievable by a full-scale system.
9.6.1 Federal MCLs and Tennessee Groundwater Standards
For those contaminants for which Federal Maximum Contaminant Levels (MCLs) and/or Tennessee
Groundwater Quality Standards are available, discharge levels equal to the chemical-specific ARARs are
technically achievable and provide adequate protection of human health and the environment.' The
discharge levels are listed in Table 9-1.
9.6.2 Hearth Advisories
For RDX, 2,4,6-TNT, HMX, and 1,3-DNB, EPA has developed Health Advisory levels using the
assumption that 80% of human exposure to the contaminants occurs through pathways other than
ingestion of groundwater (such as ingestion of crops irrigated with groundwater, showering and bathing,
and inhalation). These Health Advisories are not TBC standards for this interim remedial action because
the remedy will ensure protection of human health and the environment through active groundwater
remediation and institutional controls.
9-7
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TABLE 9-1
Discharge Levels for Contaminants of Concern
Contaminant of Concern
Discharge
Concentration
fog/L)
Source or Description
INORGANIC CONSTITUENTS
Nitrate
10,000
Federal Maximum Contaminant Level
VOLATILE ORGANIC COMPOUNDS
Carbon Disulfide
3,500
Derived from Reference Dose (RfD); the
concentration corresponds to the level at which no
adverse health effects will result from daily
ingestion of 2 L of water over a lifetime
EXPLOSIVES COMPOUNDS
1 ,3-Dinitrobenzene
2,4-Dinitrotoluene
2,6-Dinrtrotoluene
HMX
Nitrobenzene
RDX
1 ,3,5-Trinitrobenzene
2,4,6-Trinitrotoluene
5
0.5
0.5
2,000
17.5
10
20
10
USEPA Office of Drinking Water Lifetime Health
Advisory, assuming 100% exposure occurs through
ingestion of water
Derived from Cancer Slope Factor (SF), assuming
an excess cancer risk of 10"8 and lifetime exposure
to 2 L of water per day
Derived from SF, assuming an excess cancer risk of
10"9 and lifetime exposure to 2 L of water per day
USEPA Office of Drinking Water Lifetime Health
Advisory, assuming 100% exposure occurs through
ingestion of water
Derived from Reference Dose (RfD); the
concentration corresponds to the level at which no
adverse health effects will result from dairy
ingestion of 2 L of water over a lifetime
USEPA Office of Drinking Water Lifetime Health
Advisory, assuming 100% exposure occurs through
ingestion of water
Propo*ed discharge level, based on treatabilify
study data, technical feasibility, and cost
USEPA Office of Drinking Water Lifetime Health
Advisory, assuming 100% exposure occurs through
ingestion of water
Total excess cancer risk: 6 x 10"5
9-8
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The baseline risk assessment conducted for the groundwater operable unit indicates that under
the residential future land use scenario (the most stringent future land use conditions), all significant
potential human health risk is due to ingestion of groundwater as drinking water. Other risk pathways are
far more secondary because of the nature of the contaminants, which are not volatile and do not pose
significant risk via the dermal contact exposure route. Also, crop irrigation is not widely practiced in this
region.
For the reasons given above, the concentrations corresponding to 100% exposure through
drinking water have been selected as the discharge levels. For RDX, 2,4,6-TNT, HMX, and 1,3-DNB, these
levels are 10; 10; 2,000; and 5 pQ/L, respectively. As will be discussed in the next section, it has been
estimated that the concentrations of these contaminants will not exceed the Health Advisory levels (2; 2,
400; and 1 A/g/L, respectively) at the facility boundary.
9.6.3 Other Risk-Based Guidance
EPA has classified 2,4- and 2,6-DNT as Group B2 carcinogens and has issued a Slope Factor (SF)
of 0.68 (mg/kg/day)"1 for both isomers. Based on the assumptions of a 70 kg human ingesting 2 L of
water per day for a lifetime, a concentration in groundwater of 0.5 pg/L corresponds to an excess cancer
risk of 1 x 10"5. These slope factors are TBC standards.
For carbon disulfide, nitrobenzene, and 1,3,5-TNB, EPA has issued reference doses (RfD) of 1 x
10~1, 5 x 10"4, and 5 x 10~5 mg/kg-day, respectively. For carbon disulfide and nitrobenzene, these values
have been used to calculate concentrations in water which are unlikely to result in adverse health effects.
These values are listed in Table 9-1 as 3,500 and 350 pg/L, respectively. For carbon disulfide and
nitrobenzene, these RfDs are TBC standards. For 1,3,5-TNB, the RfD is not a TBC standard for this
interim remedial action because the remedy will ensure protection of human health and the environment
through active groundwater remediation and institutional controls.
It has been concluded from the treatability study data that the rate-limiting compound for
ultraviolet oxidation, which is the preferred treatment method because of the high efficiency and lack of
treatment residuals, is 1,3,5-TNB. The retention time study indicates that 2,4,6-TNT is readily oxidized into
1,3,5-TNB, which then has greater resistance to the free hydroxyl radicals due to a molecular structure
which is less susceptible to attack. Although the concentration of 1,3,5-TNB was eventually reduced to
less than the detection limit, a relatively long retention time was needed. Therefore, if the system is
designed to treat groundwater such that the concentration of 1,3,5-TNB is reduced to extremely low levels,
the cost efficiency of the system would be greatly reduced.
Given the difficulty in reducing the concentration to extremely low levels, and the fact that
institutional controls will preclude the use of undiluted effluent as a potable water supply, a discharge
concentration of 20 yg/L is selected for this compound.
9.6.4 Estimate of Off-Site Concentrations of Contaminants after Remediation
The discharge limits developed in the previous sections specify the maximum concentrations of
explosives and other contaminants that may be in the treatment system effluent for this interim remedy.
The purpose of setting these discharge levels is to provide protection of human health within the capability
of the treatment system. To ensure that the discharge levels are sufficiently protective of off-site
groundwater users, an estimate was made of the maximum levels of contaminants in groundwater at the
facility boundary. In developing these estimates, it is assumed that the only human health exposure
pathway is the transport of contaminants to the facility boundary (approximately 9,000 feet from O-LJne)
and then ingestion of contaminated water by residents living off site.
9-9
-------
The assumption was made that the proposed action will successfully stop the further migration
of contaminated groundwater from the O-Line Ponds area and that re-injection of treated water (with
concentrations of contaminants at or below the discharge levels) will occur upgradient of the ponds. The
re-injected water will mix with both untreated contaminated groundwater and uncontaminated
groundwater. Therefore, the interim remedial action is complete, and in the absence of a final remedial
action which achieves all health-based levels, the area downgradient of the re-injection wells (and
approximately as long as the currently existing area of contaminated groundwater) will be nearly uniformly
contaminated with explosives at levels assumed to be equal to the cleanup levels. Transport of these
contaminants will then occur toward the hypothetical receptors on the facility boundary. This is a highly
idealized approximate model of contaminant transport, but existing data are not sufficient to formulate a
more detailed approach.
where:
* = porosity of the aquifer material
^current = current width of the area of contaminated groundwater;
Lcurrent = current length of the area of contaminated groundwater (greater than or
equal to the discharge level);
recurrent = current depth of the plume;
^discharge = discharge concentration;
Wfuture = future width of the area of contaminated groundwater;
Lfutura = future length of the area of contaminated groundwater;
rjfuture = future depth of the plume; and
^off-site = concentration at facility boundary.
Assuming that the width and depth of the area of contaminated groundwater are the same for the
current and future cases, the equation reduces to:
This may be expressed as:
C
air-nit
The distance from the southernmost edge of the current area of contaminated groundwater to the facility
boundary is 9,000 feet The levels of RDX in groundwater were used in estimating the current length of
the area of contaminated groundwater because available data indicate that this is the most areally
extensive contaminant. The length of the area within which the concentration exceeds the discharge level
is approximately 1,800 feet. Therefore, the off-site levels are estimated to be 5 times smaller than the
discharge levels. Using this estimated relationship between discharge levels and off-site levels, the EPA
Health Advisory levels for RDX, 2,4,6-TNT, 1,3-ONB, and HMX will be met at the facility boundary. The
discharge levels therefore provide adequate protection of human health in off-site areas.
9-10
-------
9.6.5 Achievement of Remediation Goals
Results from pilot-scale studies performed on groundwater from the O-LJne ponds indicate that
groundwater may be treated to levels below the discharge levels established for the groundwater for this
Operable Unit. Therefore, treatment of the 0-Line Ponds groundwater through the implementation of the
selected remedy will reduce the risks posed by the present groundwater to the target risk range specified
for this Operable Unit.
9.7 COST OF THE SELECTED REMEDY
A summary of the costs for this alternative are given in Tables 9-2 (extraction system) and 9-3
(treatment and re-injection system). The total capital costs for the treatment system is $2,098,000.
Additional capital costs include $206,000 site preparation, $451,000 for the installation of a re-injection
system, and $327,000 for the extraction well system. The total present worth of this remedy is estimated
to be approximately $27,553,000 (30 years, 5% discount rate), including capital costs of $5,586,000 and
annual O&M expenditures of $1,429,000. These costs are preliminary and are subject to change
depending on final system design. Cost estimates are based on vendor information and generic unit
costs.
The capital costs for the electrochemical precipitation unit will be affected by the selected flow
rate. Although the size of the unit will affect the capital cost of the unit, cost versus flow rate is not a linear
function due to economies of scale. For the electrochemical precipitation process, flow rate is expected
to have a greater effect on equipment size than inlet contaminant concentrations because the size of the
equipment is mainly determined by the rate of flocculent settling rather than by a chemical reaction rate.
In general, polymers can be added to the groundwater to enhance settling as necessary to respond to
contaminant concentration variations. However, the sizing of ancillary equipment such as the filter press
is highly dependent upon the contaminant loading in the groundwater and the groundwater flow rate.
The most significant operating costs for electrochemical precipitation are electrical and iron
consumption. Electrical consumption and iron dosage are more linearly related to flow rate than to inlet
contaminant concentrations. The optimum dosage of iron must be determined through performance
testing should the inlet contaminant concentrations change significantly. Filter cake disposal is also a
significant operating cost; sludge volume is directly related to the contaminant loading in the groundwater
and the groundwater flow rate.
The capital cost for the UV-oxidation unit will be affected by the selected flow rate, the inlet
contaminant concentrations, and the effluent concentration desired. Although the size of the unit will
affect the capital cost of the unit, cost versus flow rate is not a linear function due to economies of scale.
The contaminant concentrations affect the required residence time, which in turn affects the size of the
equipment.
The operating costs of the UV-oxidation unit are affected by the flow rate, the inlet contaminant
concentrations, and the effluent concentration desired for this first organics treatment step. The two most
significant operating costs are electricity and oxidant consumption. Oxidant dosage is proportional to flow
rate of the system. Electrical consumption is directly related to the residence time of the groundwater in
the unit and the groundwater flow rate (i.e., the size of the unit). The effects of contaminant
concentrations on required residence time in the reactor can be estimated using reaction kinetics data
obtained during treatability testing. Residence time of the final treatment unit may be adjusted by varying
the number of operating UV lamps.
9-11
-------
Table 9-2
Summary of Costs for Extraction System
ITEM
1.
II
GENERAL ACTIONS/SITE PREPARATION
1. Contractor Mobilization/ Demobilization
Subtotal:
. EXTRACTION SYSTEM
1. Extraction Wells
2. Submersible Pumps (6 shallow well pumps)
3. Collection Piping
Subtotal:
SUBTOTAL (1, II)
111
. ADDITIONAL SYSTEM COSTS
1. Health and Safety 10X of Capital subtotal
2. Bid Contingency 15X of Capital subtotal
3. Scope Contingency(p) 15X of Capital subtotal
25X of Annual subtotal
Subtotal :
CONSTRUCTION SUBTOTAL (1, II, and III)
IV.
IMPLEMENTATION COST
J. Eng. Services During Construction 15X of system subtotal
, Engineering & Design 10X of system subtotal
Subtotal:
A.
B.
C.
TOTAL CAPITAL COSTS
TOTAL ANNUAL COSTS
TOTAL PRESENT WORTH OF ANNUAL COSTS
TOTAL PRESENT WORTH OF CAPITAL AND ANNUAL COSTS (A « C)
QUANTITY CAPITAL ANNUAL
COST 0 8 M
COST
$20,000
$20,000
6 wells $68,000
6 pumps $10,000 $13,000
2870 ft $89,000
$167,000 $13,000
$187,000 $13,000
$19,000
$28,000
$28,000
$3,000
$75,000 $3,000
$262,000 $16,000
$39,000
$26,000
$65,000
$327,000
$16,000
Present Worth
of Annual Costs
30 years, 57. 30 years, 107.
$200,000 $123,000
$200,000 $123,000
$200.000 $123,000
$46,000 $28,000
$46,000 $28,000
$246,000 $151,000
$246,000 $151,000
$573,000 $478,000
M .
-------
Table 9-3
Summary of Costs for Alternative T-7: Preclpttatlon/UV-OxIdation/GAC/Re-lnjectlon
ITEM
I. Administrative Actions
1. Institutional Restrictions/Emergency Provisions (a)
2. Public Education Program (b)
3. Program Oversight (c)
Subtotal:
II. GENERAL ACTIONS/SITE PREPARATION
1. Parking/Staging Area (c)
2. Treatment System Building Construction (d)
3. Building lighting and Heating (e)
4. Contractor Mobilization/ Demobilization
Subtotal:
III. GROUNDUATEft TREATMENT SYSTEM
1. Pre-treatment System (Precipitation) (f)
2. UV-Oxidation Unit (g)
3. Granular Media Filtration Unit (h>
4. Granular Activated Carbon (GAC) Adsorption Unit (i)
5. Part-time System Operator (j)
Subtotal:
IV. RE- INJECTION SYSTEM
1. Injection Wells
2. Horizontal Pumps
3. Discharge Piping
4. System Controls
Subtotal:
V. LONG-TERM MONITORING I REVIEW
1. Weekly Effluent I Monthly Residuals Monitoring (k)
2. Quarterly Grounduater Monitoring and Reporting (t)
3. Quarterly Surface Water Monitoring I Reporting (m)
4. Five-Year Reviews (SIS, 000 ea)
Subtotal:
SUBTOTAL (I, II, III, IV and V)
VI. ADDITIONAL SYSTEM COSTS
1. Health and Safety 10X of Capital subtotal
2. Bid Contingency 1SX of Capital subtotal
3. Scope Contingency 15X of Capital subtotal
25X of Annual subtotal
Subtotal :
CONSTRUCTION SUBTOTAL (I, II, III, IV, V and VI)
VII. IMPLEMENTATION COST
1. Eng. Services During Construction 15X of systsn subtotal
2. Engineering I Design 10X of systaai subtotal
3. Permitting/Coordination (o)
Subtotal:
A. TOTAL CAPITAL COSTS
B. TOTAL ANNUAL COSTS
C. TOTAL PRESENT WORTH OF ANNUAL COSTS
TOTAL PRESENT WORTH OF CAPITAL AND ANNUAL COSTS (A * C)
QUANTITY CAPITAL
COST
115,000
$20,000
*35,000
1200 sq ft $1,000
7500 sq ft $150,000
S35.000
$20,000
1206,000
USD, 000
$980,000
$95,000
$165,000
2180 hrs/yr $8,000
$2,098,000
3 wells $99,000
3 punps $11,000
4450 ft $316,000
$25,000
$451,000
$200,000
6 tiells
6 reports
$200,000
$2,990,000
$299,000
$449,000
$449.000
$1,197,000
$4,187,000
$628,000
$419,000
$25,000
$1.072,000
$5,259,000
ANNUAL
0 t M
COST
$75.000
$75,000
$7,000
$7,000
$200,000
$368,000
$53,000
$94,000
$44,000
$759,000
$5,000
$26,000
$31,000
$121,000
$67,000
$67,000
$3,000
$258,000
$1,130,000
$283,000
$283,000
$1,413,000
$1,413,000
Present
of Annual
30 years, 5X
$1,153,000
$1,153,000
$108,000
$108,000
$3,074,000
$5,657,000
$815,000
$1,445,000
$676,000
$11,667,000
$77,000
$400,000
$477,000
$1,860,000
$1,030,000
$1,030,000
$46,000
$3,966,000
$17,371,000
$4,350,000
$4,350,000
$21,721,000
$21,721,000
$26,980,000
Worth
Costs
30 years, 10X
$707,000
$707,000
$66,000
$66,000
$1,885,000
$3,469,000
$500,000
$886,000
$415,000
$7,155,000
$47,000
$245,000
$292,000
$1,141,000
$632,000
$632,000
$28,000
$2.433,000
$10,653,000
$2,668,000
$2,668,000
$13,321,000
$13,321,000
$18,580,000
9-13
-------
Table 9-3 (cont'd)
Summary of Costs for Alternative T-7: PreclpHatlon/UV-OxIdatlon/GAC/Re-lnJectlon
NOTES AND ASSUMPTIONS
(a) For controlling access to contaminated areas, restricting future property use,
and restricting the drilling of new drinking water wells.
(b) - To increase public awareness of hazards through press releases, presentations, and posting of signs.
(c) - Costs include the annual salary of one program oversight manager for the groundwater treatment program.
Costs do not include government oversight of this task,
(d) - 30 ft x 40 ft staging area of 8" deep gravel.
(e) Includes a 75 ft x 100 ft prefabricated steel building, 6" concrete base, insulation, electrical wiring, and plumbing.
(f) - Lighting consists of 25 8' fluorescent lights
(a) - Includes electrochemical precipitation system consisting of a reactor,
a clarifier, a granular media filtration unit, a filter press, assorted1pumps and tanks.
Operating costs of S0.25/ lOOOgal wastewater include power and maintenance.
. The amount of sludge removed is estimated at 15 cubic feet/day » S180/55 gal drum.
(h) - Includes 3 SOOOgal contactors, 4 reactors, and ozone generator. Operating costs include
ozone and electrical costs.
(i) - Includes 3 vessel multi-media filter skid with punps, influent and effluent tanks.
Operating costs of S0.20/ 1000 gal wastewater.
(j) Includes 2 20,0001b adsorbers connected in series. Annual costs include delivery
and cost of activated carbon.
(k) - Part-time system operator is assumed to cost *20/hr and is used approximately 1 8hr shift per day.
(1) - Sixty effluent samples will be taken per year and analyzed for TAL/TCL, explosives, and cyanide.
The analytical costs are 12000 per sample. The residual samples (24/y*ar) will b* tested for TCLP metals and VOCs,
corrosivity, ignitability and reactivity at a cost of S700 per sample.
(m) - The cost for well sampling la $2240 per sampling event. Six (6) wits are proposed.
The analytical costs are S2000 per sample, tested for TAL/TCL, explosives and cyanide.
(n) - The costs for surface water sampling is S2260 per sampling event. Six locations are proposed to be monitored quaterly.
Surface water will be tested for TAL/TCL, explosives and cyanide at a cost of 12000 per sample.
(o) - Cost includes permit application process and/or coordination with state/federal officials regarding discharge of treated water.
TAL/TCL - Target Analyte List/Target Compound List
TCLP - Toxicity Characteristic Leaching Procedure
VOC - volatile organic compounds
9-14
-------
GAG units are designed to provide an adequate contact time given a maximum flow rate. If the
flow rate is lower than assumed and the contaminant concentrations are constant, a smaller unit can be
specified, the depth of the carbon bed (i.e., the contact time) will not be reduced; however, the cross-
sectional area of the unit would be reduced. If the flow rate is higher than that assumed and the
contaminant concentrations are held constant, a larger unit (i.e., larger cross-sectional area to
accommodate the higher flow rate) or a number of small adsorption units in parallel can be designed.
In this case, the depth of the carbon bed(s) will be held constant. As with the other treatment units, the
cost of the GAG unit will vary with flow rate; however, cost versus flow rate is not a linear function due to
economies of scale. The carbon usage rate is also dependent upon the flow rate. If the flow rate is lower
than that assumed and the inlet contaminant concentrations are held constant, the carbon usage rate will
be lower because the unit is smaller (i.e., holds less carbon) even though the carbon bed life (i.e., time
to contaminant breakthrough) does not change. If the flow rate is higher than that assumed and the inlet
contaminant concentrations are held constant, the carbon usage rate will be higher because the unit is
larger (i.e., holds more carbon) even though the carbon bed life does not change.
The only effect that a change in inlet contaminant concentrations will have on the carbon
adsorption unit is on operating costs (i.e., purchase of activated carbon and regeneration/disposal of
spent carbon). That is, if the inlet concentrations are lower than assumed (due to extended treatment
through UV-oxidation or a decrease in contaminant levels in the groundwater over time), the carbon
adsorption bed will have a longer life (i.e., greater time to contaminant breakthrough) and will have to be
changed out less frequently; if the inlet contaminant concentrations are higher than assumed, the carbon
adsorption bed will have a shorter life and will have to be changed out more frequently.
Re-injection costs are dependent on flow rate only. If the effluent flow from the treatment system
is increased, a greater number of re-injection wells will be needed, increasing capital and operating costs.
Likewise, if the effluent flow is decreased, fewer wells will be needed to re-inject the water into the aquifer
and capital and operating costs will decrease.
9-15
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10.0 STATUTORY DETERMINATIONS
Executive Order 12580 delegates the authority for carrying out the requirements of CERCLA
sections 104(a), (b), and (c)(4) and 121 to the Department of Defense, to be exercised consistent with
section 120 of the Act. Therefore, under its legal authorities, the Army's primary responsibility at MAAP
is to undertake a remedial action that achieves adequate protection of human health and the environment.
In addition, section 121 of CERCLA establishes several other statutory requirements and preferences.
These specify that when complete, the final remedial action for the O-Line Ponds area must comply with
applicable or relevant and appropriate environmental standards established under Federal and State
environmental laws unless a statutory waiver is justified. The final 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 statute includes a preference for remedies that employ.
treatment that permanently and significantly reduce the volume, toxicity, or mobility of hazardous
substances as their principal element. The following sections discuss how the selected interim remedy
is consistent with these statutory requirements as far as practicable given the limited scope of the action.
10.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
The selected remedy will contain and remove contaminated groundwater from the ground, thereby
reducing the risk posed by this potential exposure pathway. This alternative extracts contaminated
groundwater, treats it to remove contaminants below the discharge levels listed in Section 9.6 of this ROD,
and re-injects the treated water into the aquifer. Groundwater quality will be improved by implementation
of the selected remedy and potential health risks will be significantly reduced. No unacceptable short-
term risks or cross-media impacts will be caused by implementation of the remedy.
Although contamination will remain within the Operable Unit above health-based levels, institutional
controls will prevent contact with these contaminants until a final groundwater remedy is implemented.
10.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
The ARARs for this Operable Unit include action-specific, chemical-specific and location-specific
requirements. To-be-considered (TBC) guidance are also listed.
10.2.1 Actlon-Spectflc ARARs
This remedy will be operated in accordance with all Federal and Tennessee treatment facility
requirements. A list of action-specific ARARs and TBC guidance is presented in Table 10-1.
According to Rule 1200-4-6-.14 of the State of Tennessee Water Laws, re-injection of treated
groundwater is permissible. A Class V injection well may be used provided that no hazard to existing or
future use of the groundwater as cited in rule 1200-4-6-.05 exists. Groundwater usage under this later
rule includes domestic water supply, industrial water supply, livestock watering and wildlife, surface water
drainage, and irrigation. The rule stipulates that groundwater used for these purposes may be subject
to treatment prior to the actual use. Treatment of extracted groundwater will take place prior to use of
a Class V injection well for re-injection, and therefore will not disqualify the groundwater from being used
for any of the stated uses in the rule.
10-1
-------
Table 10-1
Identification of Action-Specific ARARs and To-Be-Considered Guidance
Authority
Requirement
Status
Requirement Synopsis
Federal Regulatory
Requirement
O
rb
National
Environmental
Policy Act (NEPA)
of 1969
Applicable
Federal actions may not result in environmental damage.
Occupational Safety
and Hearth Act
(OSHA) - General
Industry Standards
(29 CFR 1910)
Applicable
These regulations specify the 8-hour time-weighted average concentration for various organic
compounds. Training requirements for workers at hazardous waste operations are specified in
29 CFR 1910.120.
OSHA Safety and
Hearth Standards
(29 CFR 1926)
Applicable
This regulation specifies the type of safety equipment and procedures to be followed during
site remediation.
OSHA-
Recordkeeplng,
Reporting, and
Related Regulations
(29 CFR 1904)
Applicable
This regulation outlines the recordkeeping and reporting requirements for an employer under
OSHA.
Resource
Conservation and
Recovery Act
(RCRA). RCRA
Subtitle C (40 CFR
260)
Relevant and
Appropriate
RCRA regulates the generation, transport, storage, treatment, and disposal of hazardous waste.
CERCLA specifically requires (in Section 104(c)(3)(B)) that hazardous substances from
remedial actions be disposed at facilities in compliance with Subtitle C of RCRA.
RCRA - Standards
for Owners and
Operators of
Permitted
Hazardous Waste
Facilities (40 CFR
264.1 - 264.8)
Relevant and
Appropriate
General facility requirement include general waste analysis, security measures, inspections,
and training requirements.
RCRA-
Preparedness and
Prevention (40 CFR
264.30-264.31)
Relevant and
Appropriate
This regulation outlines requirements for safety equipment and spill control.
-------
Table 10-1 (cont'd)
Identification of Action-Specific ARARs and To-Be-Considered Guidance
Federal Regulatory
Requirement
Federal Guidance
State Regulatory
Requirement
RCRA -
Contingency Plan
and Emergency
Procedures (40 CFR
264.50 - 264.56)
RCRA-
Groundwater
Protection (40 CFR
264.90 - 264.109)
RCRA - Closure and
Post-Closure (40
CFR 264.1 10-
264.120)
National Ambient
Air Quality
Standards (40 CFR
Part 50)
USEPA
Groundwater
Protection Strategy
USEPA Policy
Statement (August
1984)
State of Tennessee
Water Laws (Rule
1200-4-6-.14)
State of Tennessee
Ambient Air Quality
Primary Standards
(Rule 1200-3-3-.03)
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Applicable
To be considered
Applicable
Applicable
This regulation outlines the requirements for emergency procedures to be used following
explosions, fires, etc.
This regulation details requirements for a groundwater monitoring program to be installed at
the site.
This regulation details specific requirements for closure and post-closure of hazardous waste
facilities.
Federal agencies are required to determine if the site is located in a non-attainment zone for
ozone. Sites within non-attainment areas must consider the ozone attainment status in
designing remediation systems.
Identifies groundwater quality to be achieved during remedial actions based on the aquifer
characteristics and use.
The requirements for a Class V injection well are listed.
Identifies the air quality standards for ozone.
-------
Since land re-surfacing and construction activities will be performed upon implementation of a
treatment alternative, air quality ARARs are applicable. For each technology within this remedy, applicable
air quality regulations will be met. UV-oxidation requires the generation of ozone, a regulated substance,
for use as an oxidant. The Tennessee Ambient Air Quality Primary Standard for ozone is 0.12 mg/L by
volume (Rule 1200-3-3-.03).
In regards to disposal of the spent carbon and precipitation filter cake, important potential ARARs
are the Land Disposal Restrictions (LDRs) implemented by EPA under the Hazardous and Solid Waste
Amendments (HSWA). Under these restrictions, hazardous waste may not be landfilled without meeting
the prescribed treatment standard. If these restrictions are applicable (i.e., if the spent carbon and/or filter
cake are determined to constitute a hazardous waste), then the disposal of the wastes will be performed
in compliance with the LDRs.
10.2.2 Chemlcal-Specfflc ARARs
The selected interim remedy provides a means of reducing the levels of contamination in extracted
groundwater to below clean up levels set by ARARs and TBCs at the facility boundary and will achieve
these levels within the facility for most contaminants. The remedy will significantly reduce the
concentrations of RDX, 2,4,6-TNT, HMX, and 1,3-DNB within the Operable Unit; however, the health-based
limits applicable to these constituents may not be achieved within the facility boundary during this interim
action. Further remediation of groundwater within the Operable Unit may be addressed in the subsequent
final remedial action. To ensure protection of human health and the environment while the subsequent
action is being developed, institutional controls will be used to prevent use of the water.
More stringent Maximum Contaminant Level Goals (MCLGs), established by the Safe Drinking
Water Act, are not relevant and appropriate standards given the risks posed by the Operable Unit.
All groundwater ARARs will be achieved through the implementation of the selected remedy.
Applicable groundwater ARARs and TBC guidance are listed in Table 10-2.
10.2.3 Location-Specific ARARs
The construction and operation of the treatment facility and extraction/re-injection wells
incorporated in this remedy will comply with all location-specific ARARs. A list of location-specific ARARs
and TBC guidance is presented in Table 10-3.
10.3 COST EFFECTIVENESS
By implementing both UV-oxidation and GAC for the treatment of explosives in groundwater, the
selected remedy represents the best cost/benefit ratio, being only incrementally more costly than the
lowest cost option while providing greater protection to human health and the environment.
10.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE TREATMENT
TECHNOLOGIES (OR RESOURCE RECOVERYTECHNOLOGIES) TO THE MAXIMUM EXTENT
PRACTICABLE
The selected remedy is not designed or expected to be the final treatment for groundwater at
the site; however, the remedy represents the best balance of trade-offs among alternatives, given the
limited scope of the action. The selected remedy permanently removes contaminants from the
10-4
-------
Table 10-2
Identification of Chemclal-Speclflc ARARs and To-Be-Consldered Guidance for Groundwater
/'Nv-A«th9fliy;-' "
Federal Regulatory
Requirement
State Regulatory
Requirements
Federal Criteria.
Advisories, and
Guidance
:i';::: Requirement!; :: ;;
Safe Drinking Water
Act(SDWA)-
Maxlmum
Contaminant Levels
(MCLt), 40 CFR
141.11-141.16
Rules of the
Tennessee
Department of
Health and the
Environment,
Chapter 1200-5-1-
.06
EPA Carcinogen
Assessment Group
Potency Factors
EPA Office of
Drinking Water
Hearth Advisories
(HAs)
EPA Risk Reference
Doses (RfDs)
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Relevant and
Appropriate
Relevant and
Appropriate
To Be Considered
To Be Considered
To Be Considered
; \:::;:; : ; : Requirement Synopsis
MCLs have been promulgated for a number of common organic and inorganic contaminants.
These levels regulate the concentration of contaminants in public drinking water supplies
based on health effects and technical capabilities. MCLs may also be considered relevant and
appropriate for groundwater aquifers potentially used for drinking water.
The State of Tennessee has adopted groundwater standards and public water supply
standards.
Potency factors are developed by EPA from health effects assessments or evaluation by the
Carcinogen Assessment Group. Carcinogen potency factors are used in the baseline risk
assessment to compute the individual incremental cancer risk resulting from exposure to site
contaminants.
Hearth advisories developed from estimates of risk due to consumption of contaminated
drinking water considering noncarcinogenic effects only. Hearth advisories are considered for
contaminants In groundwater that may be used for drinking water.
RfDa are dosa levels developed by EPA for non-carcinogenic effects. RfDs are used in the
baseline risk assessment to characterize risks due to exposure to non-carcinogenic
contaminants In groundwater.
9
en
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Table 10-3
Identification of Location-Specific ARARs and To-Be-Considered Guidance
Authority
Requirement
Status
Requirement Synopsis
Federal Regulatory
Requirement
9
o>
RCRA - Location
Standards (40 CFR
264.18)
Relevant and
Appropriate
This regulation outlines the requirements for constructing a RCRA facility on a 100-year
floodplain. The facility must be designed, constructed, operated, and maintained to avoid
washout by a 100-year flood, unless waste may be removed safely before floodwater can reach
the facility or no adverse effects on human health and the environment would result if washout
occurred.
RCRA - Location
Standards (40 CFR
264.16)
Relevant and
Appropriate
This regulation prohibits new treatment, storage, or disposal of hazardous waste within 61
meters (200 feet) of a fault displaced in Holocene time.
Executive Order
11988: Floodplain
Management (40
CFR 6. Appendix A)
To be considered
Federal agencies are required to reduce the risk of flood loss, to minimize the impact of floods,
and to restore and preserve the natural and beneficial values of floodplains.
Executive Order
11990: Protection of
Wetlands (40 CFR
6, Appendix A)
To be considered
Federal agencies are required to .minimize the destruction, loss, or degradation of wetlands,
and preserve and enhance the natural and beneficial values of wetlands. .
National
Archaeological and
Historic
Preservation Act (16
USC 469); National
Historic Landmarks
Program (36 CFR
65)
Relevant and
Appropriate
Federal agencies must take action to recover and preserve artifacts within areas where action
may cause irreparable harm, loss, or destruction of significant artifacts.
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extracted groundwater and returns the treated water back to the aquifer. UV-Oxidation through the use
of ozone and ultraviolet light is capable of breaking down contaminants without generating residuals. This
technology is considered an innovative technology and was evaluated in the EPA's Superfund Innovative
Technology Evaluation Program (SITE) in 1990 (USEPA, 1990b). A relatively small amount of GAC will
be used as a polishing step in this remedy. Although partially addressed in the selected remedy, the
statutory preference for remedies that employ treatment that reduces toxicity, mobility, or volume as a
principal element will be addressed by the final response action for groundwater.
The remedy was selected with consideration given to the five primary balancing criteria This
remedy is the most effective alternative because it removes both inorganic and organic contaminants from
the groundwater. This remedy also reduces the toxicity, mobility or volume of the groundwater through
active extraction and treatment. Although other alternatives generated less residuals by not implementing
the use of QAC, this alternative was chosen because the additional organics treatment step ensures
complete treatment of the groundwater. Short-term effectiveness does not play a large role in the
selection of a remedy because all alternatives require the construction of an extraction system and a
treatment plant. The selected remedy, however, is slightly more effective in the short-term because this
remedy does not generate a large quantity of residuals to be handled and disposed. Although the
selected remedy is not the easiest alternative to implement of all the alternatives considered, due to the
implementation of three different treatment technologies, the added effectiveness outweighs the added
difficulty in implementing this option. The selected remedy costs only slightly more than the least costly
alternative yet provides greater protection to human health and the environment.
Of the five primary balancing criteria discussed above, long-term effectiveness and permanence
and cost were the most decisive factors. The selected remedy provides the most economical means of
attaining the highest degree of treatment effectiveness. EPA, the State of Tennessee, and the community
accept this alternative.
10.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
The selected remedy satisfies the statutory preference to utilize permanent solutions and treatment
technologies to the maximum extent practicable. An innovative technology, UV-oxidation, will be used to
remove the organic contaminants from groundwater such that the treatment system effluent will not
contain contaminants above the discharge levels presented in Section 9.6. During the first year of
operation, a performance evaluation will be conducted to determine if the treatment plant is capable of
meeting the health-based levels on a consistent basis.
Contaminants in the groundwater which have been detected well above health-based guidance
levels pose a potential threat to future residents of the area By extracting the contaminated groundwater,
treating it through the use of electrochemical precipitation, UV-oxidation and GAC to levels below
remediation goals, and re-injecting it back into the aquifer, this remedy offers the best approach to
protecting off-site groundwater conditions and reducing the risks posed by on-site conditions.
This interim remedy only addresses OU1 and does not address contaminated soil, surface water
or sediment present at the O-Urte Ponds area These media are incorporated into OU 2, which will be
addressed by the Army.
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11.0 DOCUMENTATION OF SIGNIFICANT DIFFERENCES
During EPA and State of Tennessee review of the Proposed Plan, the draft Treatability Study
Report, and the draft ROD for OU 1, it was determined that the most appropriate means of expediting the
proposed remedy for this Operable Unit is through an Interim Action Record of Decision. This is
considered by the Army, EPA, and State of Tennessee to be a significant change. As required by Section
117(b) of CERCLA, the rationale for this significant change is documented in this ROD and in the
Administrative Record. This significant change will not result in a change in cost, timing, or level of
performance of the remedy.
The decision to address the remedy with an Interim Action ROD was made for the following
reasons:
The treatability study data for the UV-oxidation process indicates that although this
technology is highly effective in removing explosives compounds from groundwater, the
rate-limiting compound is 1,3,5-trinitrobenzene (1,3,5-TNB).
The Drinking Water Equivalency Level (DWEL) for 1,3,5-TNB, as set by the EPA Reference
Dose, is 2 /jg/L The treatability study data indicate that the proposed treatment system
may not be able to achieve this level of removal efficiency at full scale, given the expected
high flow rate and high influent concentrations. Because 1,3,5-TNB may not be removed
to health-based levels, and the performance data necessary to document selection of
alternative standards are not yet available, the proposed remedy cannot be considered
the final remedy for the site.
Although the Army is uncertain that the DWEL FOR 1,3,5-TNB can be met, the decision
was made to move ahead with the action so that contaminated groundwater can be
extracted and treated using the proposed system, which represents best available
technology. Such an action may be performed under an Interim Action ROD.
The Army is committed to providing a final remedy for the site which satisfies all health-based
criteria or provides technical data, consistent with CERCLA and the National Contingency Plan, which
justifies alternative standards.
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12.0 REFERENCES
Cody et al. 1,3-Dinitrobenzene: Toxic effect in vivo and in vitro. J. Toxicol. Environ. Health 7(5):
829-847, 1981.
Jackson Sun. June 27, 1992.
Milan Mirror Exchange. June 24, 1992.
Registry of Toxic Effects Of Chemical Substances (RTECS), 1983. U.S. Department of Health and Human
Services, National Institute for Occupational Safety and Health.
USAEHA, U.S. Army Environmental Hygiene Agency, U.S. Department of the Army. 1978.
Potable/Recreational Water Quality Survey No. 31-24-0163-79, Milan Army Ammunition Plant.
March 28, 1978.
USATHAMA, U.S. Army Toxic and Hazardous Materials Agency, U.S. Department of the Army. 1978.
Installation Assessment of Milan Army Ammunition Plant. Report No. 122. June 1989.
USATHAMA, U.S. Army Toxic and Hazardous Materials Agency, U.S. Department of the Army. 1982a.
Milan Army Ammunition Plant Contamination Survey. Report DRXTH-FS-FP-82131. Pugh, D.L:
Envirodyne Engineers. January 1982.
USATHAMA, U.S. Army Toxic and Hazardous Materials Agency, U.S. Department of the Army. 1982b.
Milan Army Ammunition Plant O-Line Settling Ponds Closure Plan. Wirth, P.K. September 1982.
USATHAMA, U.S. Army Toxic and Hazardous Materials Agency, U.S. Department of the Army. 1991.
Milan Army Ammunition Plant Remedial Investigation Report. Okusu, N., et al.: ICF Technology,
Inc., Fairfax, VA. December, 1991.
USATHAMA, U.S. Army Toxic and Hazardous Materials Agency, U.S. Department of the Army. I992a.
Milan Army Ammunition Plant Focused Feasibility Study for Operable Unit One Groundwater
Alternatives. McKendry, J., et al.: ICF Technology, Inc., Fairfax, VA. July, 1992.
USATHAMA, U.S. Army Toxic and Hazardous Materials Agency, U.S. Department of the Army. 1992b.
Milan Army Ammunition Plant O-LJne Ponds Groundwater Operable Unit Proposed Plan. July,
1992.
USEPA, U.S. Environmental Protection Agency. 1988a Integrated Risk Information System (IRIS). U.S.
Environmental Protection Agency, Office of Health and Environmental Assessment. EPA/600/8-
86/032a
USEPA, U.S. Environmental Protection Agency 1988b. Health Advisory for Octanydro-1,3,5,7-tetranitro-
1,3,5,7-tetrazocine(HMX). Office of Drinking Water. Washington, D.C. November 1988.
USEPA, U.S. Environmental Protection Agency. 1988c. Drinking Water Health Advisory for Hexahydro-
1,3,5-trinitro-1,3,5-triazine (RDX), U.S. Environmental Protection Agency, Office of Drinking Water.
November 1988.
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