Anniston Army Depot 2020 Five Year Review EPA Independent Assessment and Protectiveness Determination

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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION 4

SAM NUNN ATLANTA FEDERAL CENTER
61 FORSYTH STREET
ATLANTA, GEORGIA 30303-8960

Attn: Marvin L. Walker
Colonel, U.S. Army
Commanding
Anniston Army Depot
7 Frankford Avenue
Building 7 TAAN-CO
Anniston, AL 36201

Dear Colonel Walker:

The U.S. Environmental Protection Agency received the draft Fifth Five-Year Review (FYR) Report for
Anniston Army Depot (ANAD), Anniston, Alabama (Draft Report). However, the Draft Report's late
submittal has left insufficient time for review, comment, revision, and preparation of a final report by
the statutory due date of September 22, 2020. As a result, the EPA is making an independent finding of
the protectiveness of the remedies in order to meet the due date.

The Agency will evaluate the remedy for each operable unit (OU) addressed in the Draft Report based
on information contained in the Draft Report, as well as OU decision documents and other primary and
secondary documents in the administrative record. The Agency will also consider information provided
by the Army during regulatory oversight of work being completed under the Comprehensive
Environmental Response, Compensation, and Liability Act and the National Contingency Plan since the

Pursuant to the EPA's FYR guidance, the Agency has prepared the EPA Independent Assessment and
Protectiveness Determination (enclosed), which presents the Agency's findings, including
protectiveness determinations and recommended actions necessary to resolve the identified issues and to
ensure remedy protectiveness in the long-term. It is important that the Agency's recommendations be
addressed in a timely manner to ensure that releases do not present an unacceptable risk to human health
and the environment.

The EPA tracks issues and recommendations that affect current and future protectiveness in the
Superfund Enterprise Management System database. Additionally, the Agency reports Protectiveness
Statements for each site to Congress annually. Protectiveness statements that will be reported to
Congress for ANAD's fifth FYR are as follows:

OU1: The interim remedy at OU1 currently protects human health and the environment because an
effective point of use treatment system is in place at the drinking water source for the region;
contaminants are monitored, reported, and evaluated; and on-base land use controls (LUC) and/or
private well monitoring and notices are implemented. The construction completed portions of the
Enhanced Groundwater Interceptor System and the Partial Source Mass Removal System are
removing mobile mass as intended, and the remaining portions are expected to do so as well once
fully constructed. However, for the remedy to be protective in the long-term, the following

last FYR.

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actions need to be taken:

•	Establish a milestone for submittal of a comprehensive OIJ1 LUC remedial design which
meets all minimum requirements of the EPA's guidance and ensures both on-site and off-site
LUC requirements are properly documented, implemented, inspected, and maintained;

•	Through an explanation of significant differences, update the Interim Record of Decision
(IROD) Contaminant of Concern (COC) list, remove footnotes, and establish cleanup levels
for cis-1,2-Dichloroethene and Vinyl Chloride, daughter product contaminants omitted from
the IROD current list of COCs, as well as any other unanticipated contaminants for which
concentrations contribute to an unacceptable cumulative risk that exceeds the upper bound of
the risk range at 1 x 10-4 or Hazard Index (HI) = 1, and/or which exceed the Maximum
Contaminant Limit (MCL) or risk based level if an MCL is not available; and

•	Sample for the emerging contaminant 1,4-dioxane with 1,4-dioxane-specific protocols to
determine if screening levels are exceeded; and if concentrations contribute to a cumulative
risk that exceeds the risk range at 1 x 10-4 or Hl=l, it should be added as a COC for OU1.

OU2: The remedy at OU2 is protective of human health and the environment. The remedy is functioning
as intended. Covers and caps with permeable geotextile fabric and gravel continue to contain
contaminated soils and prevent unacceptable human and ecological exposures. The covers have
been maintained. LlJCs are implemented to limit access and to restrict use of property, prevent
installation of wells, prevent excavation of soils, etc. Signage is in place as required and is
maintained accordingly. There were no issues reported during the last five-year period.

OU3: A protectiveness statement of the remedy at OU3 cannot be made at this time until further
information is obtained. The necessary information will be obtained by taking the action
identified below, after which a protectiveness determination will be made.

•	Resume monitoring for all OU3 Record of Decision (ROD) COCs in the next round of
sampling in the spring of 2021 so that the data can be used to determine if the remedy is
functioning as intended.

It is expected that these actions will take approximately eight months to start. A FYR Report
Addendum is required after data is available and a protectiveness determination made.
Additionally, the following actions need to be taken in order for the remedy to be considered
protective in the long-term:

•	Conduct additional studies to determine the nature and extent of contamination and, if
warranted, refine the plume boundaries at Solid Waste Management Units 8, 10, and 11;

•	Complete a Non-Time Critical Removal Action (NTCRA) for Building 172 and subsurface
contamination in a timely manner;

•	Continue collecting monitored natural attenuation (MNA) parameter data and complete an
MNA evaluation for RDX and TNT after the NTCRA is complete. If it is determined that
MNA alone will not meet cleanup goals in a timely manner, evaluate remedial alternatives to
meet cleanup goals in a timely manner;

•	Complete an evaluation of site-specific background, geology, geochemistry, and other
potential factors to determine if the concentrations on site are naturally occurring or if
additional remedial actions are needed. If changes to the ROD COC list or corresponding
cleanup levels are warranted, follow the EPA's ROD guidance to do so and obtain approval;

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• Determine which contaminant(s), especially Total Chromium and/or Hexavalent Chromium,
are appropriate for inclusion as a COC and verify appropriate cleanup levels have been
established in the ROD;

• Propose, to the EPA and the Alabama Department of Environmental Management ( ADEM)
for approval, risk-based screening levels against which to evaluate RDX and TNT MNA
degradation products; and

• Perform a risk screening of recent contaminant data in accordance with the EPA's FYR
guidance to identify any contaminants for which concentrations contribute to an unacceptable
cumulative risk that exceeds the upper bound of the risk range at 1x10-4 or H1 = 1, and/or
which exceed the MCL or risk-based level if an MCL is not available; then add identified
contaminants to the ROD as a COC with enforceable cleanup levels.

Issuance of this Independent Assessment and Protectiveness Determination does not relieve the Army,
as lead agency, of the requirement to complete the FYR report. The Army should establish a revised
milestone due date of July 2, 202 1 for submittal of the Draft Final FYR Report in the FY2 1 ANAD Site
Management Plan (SMP).

Once the Agency has time to complete review of the Draft Report and to provide specific written
comments, the Army should provide the EPA responses to its comments; revise the FYR document; and
submit the revised FYR document to the EPA and A DEM for review and approval by July 2, 2021.
Whenever a protectiveness determination is deferred, as is the case for OU3, a FYR Addendum is
required. The FYR Addendum is due July 2, 2023. The Army should include this date in the FY21 SMP
for the FY23 near-term milestones. The next FYR is due on September 22, 2025.

If the Army has any questions regarding the EPA's Independent Assessment and Protectiveness
Determination for the fifth ANAD Five Year Review, please call Ms. Lila Llamas at 404-562-9969. The
Agency looks forward to working with the Army to resolve identified issues and to complete
recommended actions.

Sincerely,

C~ a DOI Digitally signed by

L.Mr\lJL CAROL MONELL

MONELL ^20.0"! 11:1*06

Carol J. M on ell. Director

Superfund & Emergency Management Division

Enclosure

cc: Mr. Jojaun Pressley
RPM, A DEM (e-copy)

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ANNISTON ARMY DEPOT 2020 FIVE YEAR REVIEW
EPA INDEPENDENT ASSESSMENT AND PROTECTIVENESS DETERMINATION

The U.S. Environmental Protection Agency received the draft fifth Five-Year Review (FYR) Report for
Anniston Army Depot (ANAD), Anniston, Alabama (Draft Report). However, the Draft Report's late
submittal has left insufficient time for review, comment, revision, and preparation of a final report by
the statutory due date of September 22, 2020. As a result, the EPA is making an independent finding of
the protectiveness of the remedies in order to meet the due date.

The Southeast Industrial Area (SIA) of ANAD was listed on the National Priorities List (NPL) on March
13, 1989. This Independent Assessment and Protectiveness Determination was conducted at this time to
meet the statutory requirement for a FYR. The triggering action for this FYR is the due date of the last
FYR, September 22, 2015. The FYR was conducted pursuant to the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) Section 121, consistent with the National
Contingency Plan (NCP)(40 CFR Section 300.430(f)(4)(ii)), and considering the EPA policy.

The purpose of a FYR is to evaluate the implementation and performance of a remedy in order to
determine if the remedy is and will continue to be protective of human health and the environment. A
five-year review is generally required by CERCLA when hazardous substances remain on site above
levels that permit unlimited use and unrestricted exposure. A FYR also reports issues identified during
the review and provides recommendations to address the issues.

The Operable Units (OU) included in this review are OU1 Southeast Industrial Area Site-Wide
Groundwater, OU2 Southeast Industrial Area Soils, and OU3 Ammunition Storage Area Soils and
Groundwater.

Regarding OU1, the Draft Report states, "Due to the complexities of the site, including site geology and
hydrogeology, potential of residual dense non-aqueous phase liquid (DNAPL) in the subsurface, high
contaminant mass estimates, high uncertainty in the mass estimates, and long estimated cleanup time
frames (potentially up to thousands of years), along with the inclusion of the aggressive bioremediation
for the Landfill, Trench, and Northeast Areas, the Army, the EPA, and ADEM agreed to an [Interim
Record of Decision] Amendment prior to a final [Record of Decision] for OU1." Therefore, the focus of
this 2020 FYR for OU1 is the 2015 Amended Interim Record of Decision (IROD). The review will
focus on whether the remedy is functioning as intended in the Amended IROD. Construction is complete
except for the last step of connecting the Enhanced Groundwater Interceptor System (eGWIS) and the
Partial Source Mass Removal (PSMR) system piping to the base main piping for two of the four areas of
OU1. The two areas connected are construction complete, and the two pending are under construction.

For OUs 2 and 3, final RODs are in place and will be the focus of the review for those OUs.

The Draft Report provides the following background information for each operable unit:

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"0U1 is referred to as the groundwater underlying the SIA and consists of
four areas of concern (AOCs): Landfill Area, Trench Area, Northeast
Area, and Industrial Area. Combined, these AOCs are additionally divided
into 7 Solid Waste Management Units (SWMUs). Components of the
amended interim remedy for 0U1 include point of use treatment
[POUT]at Coldwater Spring to maintain the Krebs Water Treatment
Plant, operation of the enhanced groundwater interceptor system
(eGWIS), bioremediation in trichloroethene (TCE) source zones [known
as the Partial Source Mass Removal (PSMR) system], long-term
monitoring (LTM) of groundwater, and land use controls (LUCs). "

"...0U2 is referred to as the SIA Soils consisting of 28 SWMUs, residing
on approximately 525 acres. Components of the selected remedies for
0U2 include no action at 14 SWMUs, LUCs at eight SWMUs, and
excavation and off-site treatment/disposal, containment, and LUCs at six
SWMUs."

"...Contaminated soils were removed, and caps were installed over
designated soil contamination areas with permeable geotextile fabric and
gravel to protect industrial workers and ecological receptors. A Dig
Permit program has been implemented in conjunction with the
implementation of signage around the SIA to prevent further
excavation/soil removal and to prevent the installation of wells except for
monitoring wells and investigation borings. "

" ...0U3 is referred to as the Ammunition Storage Area (ASA). It consists
of six SWMUs. The ASA covers 13,000 acres occupying the central and
northern portions of AN AD. Routine industrial operations at former
facilities including waste burial pits, disposal pits, sewage treatment
plants, trinitrotoluene (TNT) washout facility, deactivation furnace, and
wash racks in the ASA have resulted in contamination of soil and
groundwater. The selected remedies for 0U3 include delineation
sampling, excavation, confirmation and characterization sampling,
treatment, off-site disposal, and LUCs for soils, and monitored natural
attenuation (MNA) and LUCs for groundwater. "

QUI REMEDIAL ACTION OBJECTIVES AND REMEDIAL COMPONENTS EVALUATED:

The OU1 Remedial Action Objectives (RAOs) described in the OU1IROD Amendment are:

•	Prevent exposure of current and future residents and industrial workers to groundwater
containing concentrations of [Contaminants of Concern] (COCs) greater than maximum
contaminant levels (MCLs);

•	Minimize further migration of the contaminant plume;

•	Minimize further migration of contaminants from source areas greater than 10,000 |ig/L;

•	Return usable groundwater to its beneficial uses wherever practicable; and

•	Prevent exposure to ecological receptors (Pygmy sculpin) above the No Observable Effect
Limit (NOEL) for TCE.

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Note: Since approval of the IROD, a threshold effect concentration to be used as a site-specific response
level concentration has been established, below which is the NOEL. The Army has also made progress
on reaching agreement on actions to be taken to protect the Pygmy sculpin since the IROD was written.

OU1 IROD COCs and Cleanup Levels ICU

Contaminant of Concern

Cleanup Levels (|jg/L)

Basis

Arsenic

10

Federal MCL

Bis(2-ethylhexyl) phthalate

6

Federal MCL

Chromium (Total)

100

Federal MCL

cis-1,2-Dichloroethene(1)

70

Federal MCL

Lead

15

Federal MCL/Alabama MCL

Manganese

50

Federal SMCL

Methylene chloride

5

Federal MCL

Tetrachloroethene

5

Federal MCL

Trichloroethene

5

Federal MCL

Vinyl chloride'1'

2

Federal MCL

MCL - Maximum Contaminant Level.

SMCL - Secondary Maximum Contaminant Level.

(1) These compounds were not identified as COCs; however, they are degradation products ofTCE and
should be monitored with TCE.

Note: This footnote #1 from the IROD plays a part in an issue in this FYR Independent Assessment.

OU1 Remedial Components Include:

•	Point of Use Treatment at Coldwater Spring (POUT);

•	Enhanced Groundwater Interceptor System (eGWIS);

•	Aggressive bioremediation in each source area (a.k.a. Partial Source Mass Removal (PSMR))

•	Long-term Monitoring (LTM); and

•	Land Use Controls (LUCs).

LUC Objectives include:

•	Prevent access to or use of groundwater until cleanup levels are met; and

•	Maintain the integrity of any current or future remedial or monitoring system during its
operation, such as monitoring wells and associated piping and treatment systems.

LUCs in general include access restrictions, groundwater (GW) use restrictions, no residential use, no
dig permits, training, advisories to off-site private well owners, and LUC monitoring and maintenance.
An extensive off-site well survey was conducted to identify all existing private wells in the area. Since
that time, private well permits are required, and the Army is notified if a well permit application is
submitted. The Base Master Plan, a LUC Standard Operating Procedure (LUC SOP), a LUC
Implementation Plan (LUCIP) and a Dig Permit program address and implement LUCs for all OUs and
base-wide. The Base's Emergency Response Plan for Private Wells Anniston, Alabama implements
annual monitoring and notices to private well owners. In Section 5.3.1 Step 1. Monitor Water Quality at

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Private Wells of the Emergency Response Plan it states, "The Army will prepare and issue a report on
this annual monitoring event, including a letter to each private well owner(s). ...A phone call or visit
may be completed if the owner (s) is concerned or has questions

OU1 ISSUES AND RECOMMENDATIONS DISCUSSED:

Question A—Is the remedy functioning as intended by the decision document? (e.g. Will performance
standards likely be met? Plumes contained? Monitoring sufficient? Remedy problems? Access
Controls/ICs/LUCs in place? Removals needed? O&M issues? Cost concerns?)

1. Issue: The OU1 LUC RD has not been completed and the LUC SOP and OU1 GW LUCIP
do not include Off-site LUCs as required by the Amended IROD. On-site LUCs have been
included in the Base Master Plan and a LUC SOP has been implemented which addresses all
Amended IROD requirements for on-site OU1 GW LUCs and contains an OU1 on-site GW
LUCIP. However, LUCs for off-site private wells were not included in the LUC SOP or OU1
GW LUCIP. ANAD' s Emergency Response Plan For Private Wells Anniston, Alabama
implements annual monitoring and notices to private well owners to prevent off-site potential
exposures in the short-term, but this should be included in a CERCLA enforceable document for
long-term protectiveness. Therefore, a comprehensive LUC Remedial Design (LUC RD) that
includes both on-site and off-site GW Institutional Controls (ICs) is needed. The OU1 IROD
Amendment states, on page 2-78, "A LUC Remedial Design will be prepared as the land use
component of the Remedial Design. The Army will establish a milestone for submittal of this
LUC RD, generally within 90 days of the finalization of the IROD, and shall prepare and submit
to EPA andADEMfor review and approval a IUC RD that contains implementation and
maintenance actions, including periodic inspectionsThe Army should establish a milestone in
the SMP for submittal of a comprehensive OU1 LUC RD as required by the IROD which meets
requirements of the EPA LUC guidance including, but not limited to: Institutional Controls: A
Guide to Planning, Implementing, Maintaining, and Enforcing Institutional Controls at
Contaminated Sites, OSWER Directive 9355.0-89 EPA-540-R-09-001 December 2012; and
Recommended Evaluation of Institutional Controls: Supplement to the 'Comprehensive
Five-Year Review Guidance OSWER Directive 9355.7-18, and the Sample Federal Facility land
Use Control ROD Checklist with Suggested language (IUC Checklist), OSWER Directive
9355.6-12. This guidance should be used when revising the Draft FYR to ensure and clearly
document the Army is in compliance and human health and the environment are protected.

Recommendation: Establish a milestone for submittal of a comprehensive OU1 LUC
remedial design which meets all minimum requirements of the EPA's guidance and ensures
both on-site and off-site LUC requirements are properly documented, implemented,
inspected, and maintained.

Question B —Are the exposure assumptions, toxicity data, cleanup levels (CL), and remedial action
objectives (RAOs) used at the time of the remedy selection still valid? (e.g. Changes in standards?
Changes in land use? New pathway? New receptor? New contaminant or source? Unanticipated
COCs? Site conditions? New toxicity factors? New NOELs?)

2. Issue: Not all site contaminants have been clearly captured as COCs, nor have protective
Cleanup Levels been established in the IROD; of particular concern are

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cis-l,2-Dichloroethene (DCE) and Vinyl Chloride (VC). The FYR Guidance Section 4.2
clarifies how to answer Question B of the FYR regarding changes in exposure assumptions,
toxicity data, cleanup levels and RAOs used at the time of remedy selection. The guidance
instructs the reviewer to evaluate whether the original contaminants of concern are still valid.
Furthermore, Section 4.2.2 of the FYR guidance states "Generally, your human health
determination should be based on whether the cancer risk could now be greater than 1x10~4
and/or the hazard index could be greater than 1 for non-carcinogenic effects

The Amended IROD does not clearly identify cis-l,2-DCE and VC as COCs with enforceable
cleanup levels. The footnote for the COC table included above has historically caused confusion
as to whether or not these two contaminants are COCs for OU1. Since these two have been
omitted or insufficiently clarified, it also raises the question as to whether or not other
contaminants may have been omitted. Two of the main ways contaminants become COCs is
discussed below; one is for a contaminant to contribute to a cumulative risk that exceeds the
upper bound of the EPA's acceptable risk range at lxl0"4for carcinogenic risks or an HI=1 for
non-carcinogenic risks; the second is to exceed an enforceable standard considered to be an
Applicable or Relevant and Appropriate Requirement (ARAR), for example, in groundwater that
would be an MCL, or a risk-based concentration in absence of an MCL, when returning
groundwater to its beneficial use as a drinking water source.

On the matter of the first pathway to becoming a COC, the GW data provided in Appendix E of
the Draft FYR, indicates cis-l,2-DCE has been detected at a maximum concentration of 664,000
|ig/L and VC at a maximum concentration of 70,600 |ig/L. The drinking water human health
exposure pathway should have included exposure to cis-l,2-DCE and VC. A complete risk
assessment is not necessary to accomplish comparison of contaminant risk to the risk range for
purposes of setting this right. Using the EPA's risk estimation tools and current contaminant
concentrations as recommended by the FYR guidance, an EPA risk assessor has estimated that
recent site cis-l,2-DCE concentrations represent a non-cancer risk of tH=18,000 for a potential
future residential child and HI=11,000 for potential future residential adult receptors; and VC
concentrations represent a cancer risk in excess of lxlO"2 for potential future lifetime residential
exposure. The screening concentration for cis-l,2-DCE at a target risk of HI=1 is 36 |ig/L and
for VC at a target risk of lxlO"4 is 1.9 |ig/L, clearly indicating current concentration exceedances
of acceptable risk levels. Adding this risk to other risk for a cumulative total risk would make the
resulting risk level even higher. A similar comparison should be made for all contaminants
recently detected at OU1 to determine if they contribute to an unacceptable cumulative risk that
exceeds the risk range of lxl0"4for carcinogenic risks or an HI=1 for non-carcinogenic risks.

On the matter of the second pathway, the federal MCL is 70 |ig/L for cis-l,2-DCE and 2 |ig/L
for Vinyl Chloride. The current concentrations noted above for these contaminants exceed the
MCL. A similar comparison should be made for all contaminants recently detected at OU1.

These exceedances impact protectiveness in that the contaminants contribute to unacceptable risk
and exceed enforceable standards. For the remedy to be protective in the long-term, a
comprehensive list of contaminants contributing to an unacceptable cumulative risk exceeding
the risk range and/or an HI od 1; and/or exceeding the MCL, or a risk-based cleanup level in the
absence of an MCL, must be included in the IROD Amendment. The IROD RAOs may not be
met if the list is not complete. The remedy may not prevent exposure of current and future
residents and industrial workers to groundwater containing concentrations of COCs greater than
MCLs. Since LUCs are to be in place until cleanup levels are met, they will not be maintained if

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the COC is not listed and a CL is not established. The remedy may not return usable groundwater
to its beneficial uses wherever practicable if a COC is not listed and a CL is not established.
Granted, this is an interim remedy, however, the IROD should be corrected now. In case the
RAOs, COCs, and CLs are carried forward into a Final ROD as-is, the final remedy will be
protective also.

This change to the remedy should be considered significant and documented as an ESD since
previous tech memos and minor changes have not resulted in clarifying that cis-l,2-DCE and VC
are COCs and subject to enforceable cleanup levels. Because a point of use treatment system is
in place at the drinking water source for the region; contaminants are monitored, reported, and
evaluated; and LUCs are implemented, this issue does not impact short-term protectiveness, but
the remedy is not protective in the long term. Clarification of a complete COC list is needed.

Recommendation: Through an explanation of significant differences, update the Interim
Record of Decision (IROD) Contaminant of Concern (COC) list, remove footnotes, and
establish cleanup levels for cis-l,2-Dichloroethene and Vinyl Chloride, daughter product
contaminants omitted from the IROD current list of COCs, as well as any other
unanticipated contaminants for which concentrations contribute to an unacceptable
cumulative risk that exceeds the upper bound of the risk range at 1x10-4 or Hazard Index
(HI) =1, and/or which exceed the Maximum Contaminant Limit (MCL) or risk based level
if an MCL is not available.

3. Issue: Concerns regarding the potentially complete exposure pathway due to the presence
of 1,4-dioxane, an emerging contaminant, have not been fully addressed. The Draft Report
mentions detections in all four areas of OU1 with results in the Landfill and Trench areas having
slightly higher results, indicating possible exceedances of screening levels; however, the Army
was concerned with the sampling and analytical methods used. Therefore, the EPA considered
whether the concentrations could be accurate.

As documented by Mr. Thomas K. G. Mohr, an engineering geologist with the Santa Clara
Valley (CA) Water District and an expert in solvent stabilizers, 1,4-dioxane is a likely
contaminant at many sites contaminated with certain chlorinated solvents (particularly
1,1,1-trichloroethane [TCA]) because of its use as a solvent stabilizer. Furthermore, Mr. Mohr
reviewed Material Safety Data Sheets for various TCA manufacturers and found that 1,4-dioxane
has been included with TCA in mixtures at 2 to 8 percent by volume. The EPA conducted a
high-level review of some of ANAD's groundwater monitoring data to see if TCA exceeded
screening levels on site. The EPA found TCA results exceeded screening levels for TCA in the
Landfill and Trench areas; the same areas with questionable 1,4-dioxane results which may
exceed screening levels. This was not an exhaustive search, and exceedances may also have
occurred in the other areas, but the search was sufficient to show concerns regarding 1,4-dioxane
need to be addressed for OU1. For example, groundwater samples were collected with direct
push technology for the OU1 remedial design effort in 2017. According to the analytical data
from that effort, TCA was detected in location LF-B05-GW-1-1 at 1,600 and 2,400 |ig/L. The
different concentrations are the result of laboratory dilutions that were performed to greater
explore the range of Volatile Organic Compounds (VOC) concentrations. Using Mr. Mohr's
information regarding a range of percent by volume can provide insight to the potential
concentrations of 1,4-dioxane in the TCA observed. While not exactly precise, the multiplication
of a concentration by a percent by volume is sufficient for this explanation. For TCA at a
concentration of 1,600 |ig/L, the concentration of 1,4-dioxane could range from 32 |ig/L to 128

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|ig/L. For TCA at a concentration of 2,400 |ig/L, the concentration of 1,4-dioxane could range
from 48 |ig/L to 192 |ig/L. Considering the EPA's Tapwater Regional Screening Level (RSL) is
0.46 |ig/L for 1,4-dioxane, it is recommended that locations with relatively recent (5-10 years)
detections of TCA be slated for 1,4-dioxane analysis on the next regularly scheduled sampling of
that well(s), followed by a screening of the results as called for in Issue #2 above to determine if
1,4-dioxane should be added as a COC.

Recommendation: Sample for the emerging contaminant 1,4-dioxane with 1,4-dioxane
specific protocols to determine if screening levels are exceeded; and if concentrations
contribute to a cumulative risk that exceeds the risk range at lxlO4 or 111=1, it should be
added as a COC for OU1.

Question C: Has Any other information come to light that could call into question the protectiveness
of the remedy? (e.g. eco risks not addressed? Natural disasters?)

There is no new information that could impact protectiveness. However, there are additional issues that
do not impact protectiveness, including issues about eco risk, as discussed below.

OTHER ISSUES NOT AFFECTING PROTECTIVENESS AT OU1:

A. Delays in Construction Completion: According to Section 4.6.3.2 and also mentioned in Section
4.10.1 of the Draft Report, "Connection of the Northeast and Industrial Areas to the eGWIS is
not yet complete due to damaged underground eGWIS transmission pipesBased on initial
results of the other treatment system areas which have been fully implemented, the EPA
currently has no reason to think this portion of the system will not also operate and function as
intended. Therefore, this issue is not being considered to affect protectiveness. However, a
significant delay in completing construction would be of concern and could be considered to
affect protectiveness in the next FYR. The EPA expects the Army will work diligently to get the
pipes repaired in a reasonable timeframe, and as such, the Army should establish a milestone in
the Site Management Plan (SMP) for a Remedial Action Completion Report for this portion of
the remedy.

B. Progress toward a Proposed Plan (PP) and I ROD to address the Pvsmy sculpin in Coldwater
Spring (CWS): According to the Draft Report, Section 4.7.1 Focused Feasibility Study (FFS)
Addendum, a threshold effect concentration of 14 |ig/L of TCE was established as the
Site-Specific Response Level (RL) for TCE, below which is considered to be the NOEL.
Monitoring data has shown that the RL has not been exceeded in CWS. However, the
multi-agency task force, referred to as the Pygmy Sculpin Team, who worked to establish the
RL, also discussed the need for future potential actions due to the concentrations of TCE in the
spring nearing the RL with no way to treat the TCE directly in the spring without potentially
negatively impacting the Pygmy sculpin.

According to the Amended IROD Section 2.7.2 Summary of Ecological Risk, upon completion
of an ecological risk assessment, "¦if the risk pathway for Pygmy sculpin is identified, it will be
addressed in an addendum to the OU-1 FFS (Tetra Tech, 2012b), and an Explanation of
Significant Differences or Amendment (as appropriate) to this IROD Amendment will be issued."
The FFS Addendum is complete.

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The Pygmy Sculpin Team has also reached agreement on an additional remedial action objective
which calls for the Army to protect the integrity of the Pygmy sculpin population from potential
impacts due to VOCs in Coldwater Spring; and has identified potential actions to mitigate the
exposure and to achieve the objective. The proposed remedial actions focus additional efforts to
maintain the population in ways other than being limited to reducing concentrations of VOCs in
CWS. The Army has implemented a work plan to establish a baseline population count, establish
an off-site ark population, gather data on habitat/food sources, investigate alternative habitat, and
implement pilot projects to determine if the proposed actions can be successful. The Army is also
drafting a work plan to refine the RL through pursuing establishment of a NOEL and Lowest
Observable Effect Level (LOEL) by testing the Pygmy sculpin directly.

The Army has agreed to amend the IROD again to address these issues. The Army is currently
drafting a PP. Additional discussion will be necessary to better define this change in scope for
the OU1 IROD. The EPA recognizes the effort and time put into addressing these issues together
with the Pygmy Sculpin Team. With a focus only on the current RAO, the Draft Report falls
short of documenting the Army's commitment to follow through with the PP and IROD
Amendment, speaking only to development of the NOEL and LOEL. The EPA understands the
Army is committed to proposing and possibly selecting all of these actions, and as such, the
Army should establish a milestone in the SMP for the PP and Amended IROD to select a remedy
as described in the FFS in order to more fully address ecological exposures at Coldwater Spring
as part of OU1.

C. Technical Assessment Question A asks if the remedy is functioning as intended by the ROD.

This is an interim remedy that is not intended to be final. The IROD establishes RAOs and
ARARs; and selects remedial components which may or may not be carried forward into a Final
ROD. However, for purposes of this FYR, the following more specific short-term intent was
used to evaluate this interim action: the intent for the eGWIS to remove mobile contaminant
mass from source areas greater than 10,000 |ig/L; the PSMR to bioremediate contaminants in the
source zone such that concentrations in downgradient wells and at CWS are reduced; the POUT
system to reduce contaminants such that drinking water standards can be met at the Krebs Water
Treatment Plant (KWTP) at CWS; for LTM to monitor systems, contaminant flux, plume
migration, and concentration trends; and for LUCs to be protective until cleanup levels are met;
all of which combined should result in reducing the remedial timeframe estimated in the IROD.
Additionally, the IROD intends for efforts to lead to a Final ROD.

LUCs are in place and the POUT system has kept concentrations below the KWTP maximum
limit. Initial data results from the new eGWIS and PSMR systems obtained to date indicates the
portion of the remedy that is construction complete is functioning as intended, and the remaining
portion is expected to do so as well once completed. The EPA understands the improved system
has only been operating for a short time and that a more detailed analysis of the effectiveness of
the improved remedy will be conducted at the next FYR with 5+ years of data. At that time, it is
expected that the Army present a detailed analysis of the remedy's effectiveness on plume
migration, contaminant migration from source areas, meeting cleanup levels, and reducing the
projected remedial timeframe, in order to support a Final ROD.

D. Technical Assessment Question B asks if the RAOs used at the time of the remedy selection are
still valid. Section 4.10.2 of the Draft Report simply states that they are, without sufficient
explanation. The EPA has reviewed the RAOs and finds that it is important to at least speak to
the RAOs relative to the FYR and the intent of this interim remedy. In the most literal sense, the

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RAOs are still valid. LUCs are preventing exposures. The RAO to return groundwater to its
beneficial uses wherever practicable is standard language. Much work has been done regarding
progress toward an ecological risk NOEL for the Pygmy sculpin and an agreement was reached
to include an additional eco risk RAO in the forthcoming IROD Amendment. The remaining
RAOs are:

•	Minimize further migration of the contaminant plume; and

•	Minimize further migration of contaminants from source areas.

By using the general term minimize, the RAO is still valid. However, the Army should ensure
information and data is being obtained, monitored, reported, and evaluated through this IROD to
support deciding if the RAOs will be carried forward into the Final ROD as-is, or if they should
be refined to better represent measurable objectives in a Final ROD.

E. The IROD spells out criterion to be met regarding operation of the eGWIS and PSMR systems.
The Army should ensure that data related to the criterion are being obtained, monitored, and
reported in the groundwater monitoring reports issued by the Army. The data should be
evaluated at the time called for in the IROD, or earlier if determined to be appropriate.
Additionally, previous comments on the LTM monitoring reports have requested trend analysis
be conducted. The EPA understands the Army has agreed to address trend analysis starting with
the 2020 data reports. Meeting these needs will help ensure the Army is prepared to evaluate
IROD remedial components and specific criterion in order to move toward a Final ROD.

OU1 PROTECTIVENESS STATEMENT:

The interim remedy at OU1 currently protects human health and the environment because an effective
point of use treatment system is in place at the drinking water source for the region; contaminants are
monitored, reported, and evaluated; and on-base land use controls (LUC) and/or private well monitoring
and notices are implemented. The construction completed portions of the Enhanced Groundwater
Interceptor System and the Partial Source Mass Removal System are removing mobile mass as intended,
and the remaining portions are expected to do so as well once fully constructed. However, for the
remedy to be protective in the long-term, the following actions need to be taken:

•	Establish a milestone for submittal of a comprehensive OU1 LUC remedial design which meets
all minimum requirements of the EPA's guidance and ensures both on-site and off-site LUC
requirements are properly documented, implemented, inspected, and maintained;

•	Through an explanation of significant differences, update the Interim Record of Decision
(IROD) Contaminant of Concern (COC) list, remove footnotes, and establish cleanup levels for
cis-l,2-Dichloroethene and Vinyl Chloride, daughter product contaminants omitted from the
IROD current list of COCs, as well as any other unanticipated contaminants for which
concentrations contribute to an unacceptable cumulative risk that exceeds the upper bound of the
risk range at 1x10-4 or Hazard Index (HI) =1, and/or which exceed the Maximum Contaminant
Limit (MCL) or risk based level if an MCL is not available; and

•	Sample for the emerging contaminant 1,4-dioxane with 1,4-dioxane-specific protocols to
determine if screening levels are exceeded; and if concentrations contribute to a cumulative risk
that exceeds the risk range at 1x10-4 or HI=1, it should be added as a COC for OU1.

9

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OU2 REMEDIAL ACTION OBJECTIVES AND REMEDIAL COMPONENTS EVALUATED:

The OU2 Remedial Action Objectives described in the 2008 OU2 Final ROD are:

•	Human Health - Prevent ingestion/inhalation/direct contact of industrial workers with COCs
in excess of recommended cleanup levels at SWMUs 7, 9, 29, and 30 (lead). At sites where
future residential risks were identified, the objective is to prevent exposure of this population
to soil at SWMUs 1, 12, 13, 19, 20, 21, 22, 23, 24, and 28; and

•	Environment - Prevent exposure of ecological receptors to COCs in excess of [remedial
goals] at SWMUs 9 and 12 (cadmium, chromium, lead, and zinc) and SWMU 13 (cadmium
and zinc).

SWMUs 3, 4, 6, 25, 31, 32, 33, 38, 39, 40, 41, 42, and 43 have been designated as no further action

(NFA) for soils. SWMU 44 is designated as NFA for surface water and sediments.

The OU2 COCs and Cleanup Levels (CL) for soil presented in the ROD are:

( onlsiiiiinsuil of
Concern

Uoniodisil
(iosil (nig/kg)

lisisis

Cadmium

4

Ecological Remedial Goal Option

Chromium

64

Ecological Remedial Goal Option

Lead

220/1,350

Human Health and Ecological
Remedial Goal Option

Antimony

820

Human Health

Zinc

137

Ecological Remedial Goal Option

mg/kg = milligram per kilogram
OU = Operable Unit

SWMU = Solid Waste Management Unit

OU2 Remedial Components Include:

•	No Action - SWMUs 3, 4, 6, 25, 31, 32, 33, 38, 39, 40, 41, 42, 43, and 44;

•	Land-Use Controls - SWMUs 1, 19, 20, 21, 22, 23, 24, and 28; and

•	Excavation, Off-site Treatment/Disposal, Containment, and Land Use Controls - SWMUs 7,
9, 12, 13, 29, and 30.

LUC Objectives include:

•	Prohibit residential reuse of the site, including housing, elementary and secondary schools,
childcare facilities and playgrounds;

•	Prevent the excavation and uncontrolled removal of soil with contaminant concentration
above cleanup levels; and

•	Maintain the integrity of any existing or future monitoring or remediation systems(s).

LUCs in general include access restrictions and signs (105 signs across OU2), GW use restrictions, no
residential use, no dig permits, training, and LUC monitoring and maintenance. The Base Master Plan, a

10

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LUC SOP, a LUCIP, and a Dig Permit program address and implement LUCs for all SWMUs within the
OU.

The remedy is functioning as intended. Covers and caps with permeable geotextile fabric and gravel
continue to contain contaminated soils and prevent human and ecological exposures. The covers have
been maintained and LUCs are implemented to restrict use of property, installation of wells, excavation
of soils, etc. There were no issues reported during the last five-year period. Signage is in place as
outlined in the ROD and maintained accordingly.

OU2 ISSUES AND RECOMMENDATIONS DISCUSSED:

The EPA agrees with the Army in that no issues or recommendations were identified during the FYR
that prevents the remedy from being protective now or in the future.

OTHER ISSUES NOT AFFECTING PROTECTIVENESS AT OU2:

A. The OU2 ROD page 2-49 states "A LUC Remedial Design (LUC RD) or remedial action work
plan (LUC RAWP) will be prepared and submitted to the EPA and ADEM as the land use
component of the RD or RA WP on a schedule consistent with and enforceable under, the Federal
Facility Agreement." The Army should update the OU2 LUCIP into a LUC RD as required by
the ROD and in order to clearly meet the requirements of the EPA LUC guidance (see Issue #1
for OU1 above). Because the OU2 ROD is enforceable and actually includes detailed
information that would typically be included in the LUC RD, and because LUCs have been fully
implemented and are effective, the EPA is not considering this to affect protectiveness in this
case for the OU2 ROD. However, the Army should establish a milestone in the SMP for
submittal of a LUC RD that meets all requirements of the ROD and the EPA's guidance. The
Army will then be able to easily reference the LUC RD in all future FYRs to document
compliance and protectiveness. as opposed to having to look for the information in a very large
ROD or a LUC SOP or LUCIP using older formats and language.

OU2 PROTECTIVENESS STATEMENT:

The remedy at OU2 is protective of human health and the environment. The remedy is functioning as
intended. Covers and caps with permeable geotextile fabric and gravel continue to contain contaminated
soils and prevent unacceptable human and ecological exposures. The covers have been maintained.

LUCs are implemented to limit access and to restrict use of property, prevent installation of wells,
prevent excavation of soils, etc. Signage is in place as required and is maintained accordingly. There
were no issues reported during the last five-year period.

OU3 REMEDIAL ACTION OBJECTIVES AND REMEDIAL COMPONENTS EVALUATED:

The OU3 RAOs for soil and groundwater, as described in the 2006 OU3 ROD, are:

• Soil - Prevent exposure (i.e., ingestion, inhalation, and direct contact) of

industrial/construction workers to lead at SWMU 35 in excess of the recommended cleanup
level. This cleanup level is based on an evaluation of lead exposure levels with models to
estimate blood lead levels in the exposed population; and

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• Groundwater - Prevent exposure to groundwater and restore groundwater to its expected
beneficial uses wherever practicable through monitored natural attenuation using the
maximum contaminant levels as monitoring benchmarks for remedial goals.

The OU3 ROD addressed potential risks for exposure to soil and groundwater at SWMU 35
(Deactivation Furnace) and groundwater only at SWMU 5 (Sinkhole), SWMU 8 (Acid Disposal Pit),
SWMU 10 (TNT Washout Facility), SMWU 11 (TNT Washout Facility Leaching Beds), and SWMU 27
(South TNT Burial Pit).

The OU3 SOIL COCs are:

Chemical

Target 1IO

Target Cancer Risk

Recommended Cleanup l.e\el

(Industrial \Yorkei )|mu ku|

Lead

NA

NA

1,350

a. The industrial worker cleanup level for

ead in soil was based on t

le U.S. Environmental Protection

Agency (EPA) model for adult workers (EPA 1996). County census data were used to justify a more
realistic blood level (1.7|ig/dL and average geometric standard deviation 1.93).

The OU3 GW COCs are:

OTI3 OW COCs and Cleanup Levels

( onl a ill i nil n 1 of ( o no or ii

Clc2inii|) Level
(iiJl/l)

Itasis

Aluminum

200

Alabama MCL

Antimony

6

EPA MCL

Arsenic

10

EPA MCL

Chromium

100

EPA MCL

Iron

300

Alabama MCL

Lead

15

EPA MCL

Manganese

50

Alabama MCL

Nickel

100

Alabama MCL

Thallium

2

EPA MCL

Vanadium

11

Non-Cancer Risk-Based Value
for Potential Residential Child

1,4-DCB

75

EPA MCL

1,1-DCE

7

EPA MCL

BEHP

6

EPA MCL

N-nitroso-di-n-propylamine

0.01

Cancer Risk-Based Value
for Potential Residential Adult

RDX

0.8

Cancer Risk-Based Value
for Potential Residential Adult

2,4,6-TNT

0.8

Non-Cancer Risk-Based Value
for Potential Residential Child

12

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|ig/L = micrograms per liter

BEHP = bis(2-ethylhexyl) phthalate

DCB = dichlorobenzene

DCE = dichloroethene

EPA = Environmental Protection Agency

MCL = Maximum Contaminant Level

RDX = Royal Demolition Explosive

OU3 Remedial Components Include:

• Soil Alternative 3: Delineation Sampling, Excavation, Confirmation and Characterization
Sampling, Treatment, Off-site Disposal, and Land Use Controls - This alternative will be
used at SWMU 35; and

• Groundwater Alternative 3: Monitored Natural Attenuation and Land Use Controls
(Expanded Well Network) - This alternative is for ASA groundwater at SWMUs 5, 8, 10, 11,
27, and 35.

LUC Objectives include:

• Prevent residential reuse of the site;

• Prevent the excavation and uncontrolled removal of soil with contaminant concentrations
above cleanup levels;

• Maintain the integrity of any existing or future caps installed for the containment of
contaminants;

• Maintain and update the Installation Master Plan to include a comprehensive list of LUCs
imposed at sites, along with their mapped locations and expected durations;

• Prevent access to or use of groundwater until cleanup levels are met; and

• Maintain the integrity of any existing or future monitoring wells installed for MNA
monitoring of GW.

LUCs in general include access restrictions and signs, GW use restrictions, no residential use, no dig
permits, training, and LUC monitoring and maintenance. The Base Master Plan, a LUC SOP, a LUCIP,
and a Dig Permit program address and implement LUCs for all SWMUs within the OU.

OU3 ISSUES AND RECOMMENDATIONS DISCUSSED:

Question A Is the remedy functioning as intended by the decision document? (e.g. Will
performance standards likely be met? Plumes contained? Monitoring sufficient? Remedy
problems? Access Controls/ICs/LUCs in place? Removals needed? O&M issues? Cost concerns?)

1. Issue: OU3 Monitoring activities are inadequate to determine if the remedy is functioning
as intended or if the remedy is protective. The six SWMUs were not monitored for all
required COCs established in the Final 2006 ROD. Section 6.6.3 .2, page 54, of the Draft

Report states "The COCs... are required to be monitored at each of the SWMUs listed. However,
the 2008 Final ASA Natural Attenuation Monitoring Plan supports the evaluation of a subset of
the original COCs (SES 2008)." While it is reported that the MNA Plan supports only evaluating
a subset of the COCs, the ROD establishes the COCs and CLs and can only be modified in
accordance with the EPA's Guide to Preparing Superfund Proposed Plans, Records of Decision,

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and Other Remedy Selection Decision Documents (July 1999, OSWER 9200.1-23P) and
approval. Whereas, typically, some years of monitoring would be conducted before evaluating
results to reduce analyte lists for monitoring, information in the report indicates this decision
may have been made with insufficient data, or simply insufficient documentation of the
evaluation of data. Additionally, there was no follow through to update the ROD in accordance
with the guidance. Because COCs were omitted from the monitoring program without clear
justification, there is insufficient data to determine if the remedy is functioning as intended or if
it is protective.

The EPA recommends use of an Optimization Work Plan for optimizing monitoring activities at
superfund sites; and for clarifying decision rules and criteria for the cessation of monitoring
either individual analytes, individual wells, or across the area of concern. The Optimization
Work Plan would be applied to the analytical results from monitoring activities and
recommendations made within monitoring reports. Any changes would need approval. The EPA
also issued two sets of guidance to address these types of issues with completing long-term
monitoring, namely The Guidance for Evaluating Completion of Groundwater Restoration
Remedial Actions (OSWER 9355.0-129; November 25, 2013) and Recommended Approach for
Evaluating Completion of Groundwater Restoration Remedial Actions at a Groundwater
Monitoring Well (OSWER 9283.1-44; August 4, 2014).

Because the COC list has not been updated in the ROD and sufficient evidence is not readily
available to support a change, the Army should resume monitoring for all ROD COCs in the next
round of sampling in the Spring of 2021 in order for the remedy to be protective. The Army
should then follow the EPA's recommendation to develop an optimization work plan for OU3
MNA monitoring and meet the requirements in the guidance referenced above. The Army should
also consider pursuing other lines of evidence, such as background comparisons, geochemistry
studies, or even updating the risk assessment if warranted, so long as monitoring continues until
approved otherwise based on meeting the EPA's guidance for completing groundwater
restoration. If changes to the COC list in the ROD is warranted at some point, follow the EPA's
ROD guidance to do so and obtain approval.

Recommendation: Resume monitoring for all OU3 Record of Decision (ROD) COCs in the
next round of sampling in the Spring of 2021 so that the data can be used to determine if
the remedy is functioning as intended.

2. Issue: Plume containment is not confirmed or achieved for OU3 at SWMUs 8 for

Manganese only, and SWMU 11 for Manganese, RDX, and TNT. A potential source at
SWMU 10 may be contributing to exceedances and changes to plume boundaries at
SWMU 10 and 11. These COCs have low level exceedances of remedial goals in wells outside
the originally defined SWMU boundaries at SWMU 8 (manganese only) and SWMU 11 (RDX,
TNT, and manganese) indicating the plumes may continue to migrate beyond the SWMU
boundary. A potential source has been identified at SWMU 10 which may be contributing to
exceedances at SWMU 10 and 11. The exceedances are in a monitoring well network that is over
15 years old. Low level exceedances might be expected after a 15-year duration but should be
investigated so that plume boundaries can be validated or updated. Because LUCs prohibiting
groundwater use and well installation apply across the entire installation and to private property
wells, the issue does not affect short-term protectiveness.

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Recommendation: Conduct additional studies to determine the nature and extent of
contamination and, if warranted, refine the plume boundaries at Solid Waste Management
Units 8,10, and 11.

3. Issue: It is undetermined if the MNA remedy for Groundwater is functioning as intended
for RDX, and maybe TNT, at SWMUs 10 and 11. A potential source at SWMU 10 may be
overwhelming the capacity for MNA to achieve cleanup goals within a reasonable
timeframe without additional actions. The Draft Report indicates that remedial goals have
been exceeded in wells outside the originally defined SWMU boundaries. The Army, the EPA,
and ADEM discussed this issue and have agreed that the exceedances may be due to a continuing
source at Building 172, and that a complete assessment of the effectiveness of MNA to meet
remedial goals cannot be made until the continuing source is addressed. RDX degrades in
anaerobic/reducing conditions. Current site conditions do not favor strong anaerobic/reducing
driven attenuation of RDX. However, other natural attenuation conditions may be sufficient if
the continuing source is removed. A decision was made to address the potential source through a
surface and subsurface non-time-critical removal action (NTCRA) at Building 172; and then, if
the issue does not resolve, MNA is in question and potential remedial actions will be considered.

Recommendation: Complete a Non-Time Critical Removal Action (NTCRA) for Building
172 and subsurface contamination in a timely manner.

Recommendation: Continue collecting monitored natural attenuation (MNA) parameter
data and complete an MNA evaluation for RDX and TNT after the NTCRA is complete. If
it is determined that MNA alone will not meet cleanup goals in a timely manner, evaluate
remedial alternatives to meet cleanup goals in a timely manner.

4. Issue: It is undetermined if the MNA remedy for Groundwater is functioning as intended
for Manganese, and maybe other metals, at SWMUs 8,10 and 11. The Draft Report indicates
that remedial goals have been exceeded in wells outside the originally defined SWMU
boundaries. The Army, the EPA, and ADEM discussed this issue and have determined that the
exceedances may be due to naturally occurring elevated levels due to soil types, geology, and
geochemistry in the region. If remedial goal exceedances are due to naturally occurring elevated
levels, MNA will not be effective at reaching cleanup goals and the cleanup goals may not be
appropriate. It is important to determine if MNA will be effective for metals at OU3.

MNA for organics is different. In order to understand what needs to be done, some history of the
site and development of the ROD, as well as some insight into the MNA guidance for inorganics,
will be useful. The ROD for OU3 was signed in 2006 and the intent for the implementation of
the MNA remedy was to follow the 1999 EPA MNA Guidance principles. The following year,
2007, the EPA published the first of several MNA for Inorganic Compounds Guidance
documents. They built upon the principles of the 1999 document and other documents, but the
attenuation mechanisms for inorganics are different. The guidance states that immobilization
onto aquifer solids provides the primary means for attenuation of the inorganic groundwater
plume(s). Concentrations in groundwater typically are reduced through sorption of the inorganic
contaminant onto aquifer solids in combination with the long-term stability of the immobilized
contaminant to resist remobilization because of changes in groundwater chemistry. Precipitation
also can be a primary attenuation mechanism for inorganic contaminants, whereas it generally is
an insignificant mechanism for organic contaminants. These principles of inorganic compound
attenuation were not well understood at the time of the implementation of the monitoring plan by

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the Site team and the environmental community in general. The monitoring plan did follow the
intent of the 1999 MNA Guidance, but principles of inorganic compound attenuation did not
form the basis for the establishment of the monitoring program for OU3.

Programmatically, at OU3, there is a NTCRA planned for the removal of Building 172 and
subsurface contaminants, the believed source of the continued groundwater contamination at
SWMUs 10 and 11. The 2006 ROD specified a 10 year monitoring period which has passed, and
the monitoring program continues to be performed and assessed. This FYR is identifying
deficiencies in the OU3 ROD that have been identified more recently using the data collected in
the past 14 years, as well as the better understanding of the implementation of the Guidance for
MNA of Inorganic Compounds. After the NTCRA is complete, MNA for organics needs to be
evaluated. If MNA of organics is shown to not be effective in reaching remedial goals in a
reasonable timeframe, additional remedial action will be considered. At that time, the MNA for
organics guidance will be given full consideration to address the minor occurrences where
groundwater has migrated past the SWMU specific monitoring network established 14 years ago
together with a general re-evaluation of COCs which the Army is conducting.

Recommendation: Complete an evaluation of site-specific background, geology,
geochemistry, and other potential factors to determine if the concentrations on site are
naturally occurring or if additional remedial actions are needed. If changes to the ROD
COC list or corresponding cleanup levels are warranted, follow the EPA's ROD Guidance
to do so and obtain approval.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action

objectives (RAOs) used at the time of the remedy selection still valid? (e.g. Changes in standards?

Changes in land use? New pathway? New receptor? New contaminant or source? Unanticipated

COCs? Site conditions? New toxicity factors? New NOELs?)

5. Issue: For OU3 groundwater, it is undetermined if the COCs and cleanup levels used at the
time of the remedy are still valid. Clarity is needed regarding COCs and cleanup levels (CL),
especially pertaining to Hexavalent Chromium vs. Total Chromium; inclusion of Vanadium and
it's risk-based CL; the RDX CL; and the 2,4,6,-TNT CL. There may be other COCs and CLs that
warrant clarifying. These COCs have cleanup levels that are based on risk, rather than an MCL.
Without access to information about how these values were derived, it is unclear if these are still
appropriate CLs. However, through a comparison to RSLs and other risk-based information, an
EPA risk assessor was able to determine that the current CLs in the ROD are protective because
the CL is lower than the acceptable risk-based RSL. The Army should conduct a review of these
COCs and cleanup levels to determine if the risk-based CLs are still valid.

Regarding Hexavalent Chromium specifically, the EPA noted that risk level summaries in the
OU3 ROD indicate that Hexavalent Chromium VI was a contaminant identified as contributing
to unacceptable risk. Text in the Draft Report also indicates that it is a COC because an MCL
was exceeded, however, there is no federal MCL for Hexavalent Chromium. This point needs
clarifying. Furthermore, the EPA noted that the ROD COC list included "Chromium," as in Total
Chromium, instead of "Chromium VI," as in Hexavalent Chromium. Clarity is needed. The
cleanup level is set at 100 |ig/L, the MCL for Total Chromium. If the ROD properly reflects the
risk assessment results, the ROD COC list should be modified to identify Hexavalent Chromium
as the COC on the list. The CL should remain set at 100 |ig/L, and the basis for the CL should
indicate it is based on the MCL for Total Chromium. The ROD would then accurately capture

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the COCs, CL, and basis. This will ensure that monitoring is conducted for Hexavalent
Chromium, and future FYRs will determine if changes have been made to standards, or toxicity
factors, or other specifics for Hexavalent Chromium that would warrant a change and/or to
ensure the remedy remains protective.

The Army could also consider pursuing other lines of evidence, such as risk level screenings as
described in OU1 Issue #2, background comparisons, geochemistry studies, etc., for the other
OU3 COCs to update the COC list if warranted, so long as monitoring continues until approved
otherwise based on meeting the EPA's guidance for completing groundwater restoration. If
changes to the COC list in the ROD is warranted at some point, follow the EPA's ROD guidance
to do so and obtain approval.

Clarification of these potential issues for OU3 ROD COCs and cleanup levels is warranted.
Because the ROD CLs are protective, the Army monitors and reports both Hexavalent
Chromium and Total Chromium concentrations in groundwater, and LUCs prohibiting
groundwater use and well installation apply across the entire installation and to private property
wells, the issue does not affect short-term protectiveness.

Recommendation: Determine which contaminant(s), especially Total Chromium and/or
Hexavalent Chromium, are appropriate for inclusion as a COC and verify appropriate
cleanup levels have been established in the ROD.

6. Issue: It is unclear if TNT and/or RDX degradation products contribute to risk such that
an unacceptable risk would be generated, and therefore should be added as COCs with
established cleanup levels. The remedy for OU3 groundwater is MNA. Section 6.6.3.2, page 54,
of the Draft Report states:

" The TNT breakdown and related explosive compounds included:

•	4-Amino-2,6-dinitrotoluene (4-Amino-2,6-DNT) and 2-Amino-4,6-dinitrotoluene (2-Amino-
4,6-DNT) to provide a secondary line of evidence for the biological degradation
(breakdown) of TNT;

•	1,3,5-Trinitrobenzene (TNB), 1,3-Dinitrobenzene (DNB), and 3,5-Dinitroaniline (3,5-DNA)
to provide a secondary line of evidence for the photo-degradation of TNT; and

•	TNT related compounds, 2,4-Dinitrotoluene (2,4-DNT) and 2,6-Dinitrotoluene (2,6-DNT),
to determine the presence/absence of common impurities from the production of TNT

High Melting Point Explosive (HMX) was analyzed to provide a potential secondary line of
evidence for the anaerobic breakdown of RDX or determine if it is present (at least in part) as
an incidental co-contaminant (impurity) in the RDX."

The Draft Report also includes data in Appendix E which present results of MNA monitoring.
However, the data table does not present a screening level, nor does it indicate there have been
any exceedances of screening levels. It is unclear if there have been no exceedances because
there were not any or because there was no screening level against which to evaluate them.

Because the Army is monitoring for these contaminants; and LUCs prohibiting groundwater use
and well installation apply across the entire installation and to private property wells, the issue
does not affect short-term protectiveness.

17

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Recommendation: Propose, to the EPA and the Alabama Department of Environmental
Management (ADEM) for approval, risk-based screening levels against which to evaluate
RDX and TNT MNA degradation products.

Recommendation: Perform a risk screening of recent contaminant data in accordance with
the EPA's FYR guidance to identify any contaminants for which concentrations contribute
to an unacceptable cumulative risk that exceeds the upper bound of the risk range at 1x10-
4 or 111=1, and/or which exceed the MCL or risk-based level if an MCL is not available;
then add identified contaminants to the ROD as a COC with enforceable cleanup levels.

Question C: Has Any other information come to light that could call into question the
protectiveness of the remedy? (e.g. eco risks not addressed? Natural disasters?)

There is no new information that calls into question the protectiveness of the remedy at OU3.

OTHER ISSUES NOT AFFECTING PROTECTIVENESS AT OU3:

A. The OU3 ROD Section 2.12.2 Description of the Selected Remedies states "A LUC Remedial
Design (LUC RD) or LUC Remedial Action Work Plan (LUC RAWP) will be prepared as the
land use component of the RD or RA WP on a schedule consistent with, and enforceable under,
the Federal Facility AgreementThe Army should update the OU3 LUCIP into a LUC RD as
required by the ROD and in order to clearly meet the requirements of the EPA's LUC guidance
(see Issue #1 for OU1 above). Because the OU3 ROD is enforceable and actually includes
detailed information that would typically be included in the LUC RD, and because LUCs have
been fully implemented and are effective, the EPA is not considering this to affect protectiveness
in this case for the OU3 ROD. However, the Army should establish a milestone in the SMP for
submittal of a LUC RD that meets all requirements of the ROD and the EPA's guidance. The
Army will then be able to easily reference the LUC RD in all future FYRs to document
compliance and protectiveness, as opposed to having to look for the information in a very large
ROD or a LUC SOP or LUCIP using older formats and language.

OU3 PROTECTIVENESS STATEMENT:

A protectiveness statement of the remedy at OU3 cannot be made at this time until further information is
obtained. The necessary information will be obtained by taking the action identified below, after which a
protectiveness determination will be made.

•	Resume monitoring for all OU3 Record of Decision (ROD) COCs in the next round of
sampling in the spring of 2021 so that the data can be used to determine if the remedy is
functioning as intended.

It is expected that these actions will take approximately eight months to start. A FYR Report Addendum
is required after data is available and a protectiveness determination made. Additionally, the following
actions need to be taken in order for the remedy to be considered protective in the long-term:

•	Conduct additional studies to determine the nature and extent of contamination and, if
warranted, refine the plume boundaries at Solid Waste Management Units 8, 10, and 11;

•	Complete a Non-Time Critical Removal Action (NTCRA) for Building 172 and subsurface
contamination in a timely manner;

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•	Continue collecting monitored natural attenuation (MNA) parameter data and complete an
MNA evaluation for RDX and TNT after the NTCRA is complete. If it is determined that
MNA alone will not meet cleanup goals in a timely manner, evaluate remedial alternatives to
meet cleanup goals in a timely manner;

•	Complete an evaluation of site-specific background, geology, geochemistry, and other
potential factors to determine if the concentrations on site are naturally occurring or if
additional remedial actions are needed. If changes to the ROD COC list or corresponding
cleanup levels are warranted, follow the EPA's ROD guidance to do so and obtain approval;

•	Determine which contaminant(s), especially Total Chromium and/or Hexavalent Chromium,
are appropriate for inclusion as a COC and verify appropriate cleanup levels have been
established in the ROD;

•	Propose, to the EPA and the Alabama Department of Environmental Management (ADEM)
for approval, risk-based screening levels against which to evaluate RDX and TNT MNA
degradation products; and

•	Perform a risk screening of recent contaminant data in accordance with the EPA's FYR
guidance to identify any contaminants for which concentrations contribute to an unacceptable
cumulative risk that exceeds the upper bound of the risk range at 1x10-4 or HI=1, and/or
which exceed the MCL or risk-based level if an MCL is not available; then add identified
contaminants to the ROD as a COC with enforceable cleanup levels.

RECOMMENDED ACTION DUE DATES: The recommended actions identified above have been
captured below and given a due date as suggested by the Army. These dates will be tracked in the EPA's
Superfund Enterprise Management System database.

OU1 Action: Establish a milestone for submittal of a comprehensive OU1 LUC remedial design which
meets all minimum requirements of the EPA's guidance and ensures both on-site and off-site LUC
requirements are properly documented, implemented, inspected, and maintained. DUE 11/30/2023

OU1 Action: Through an explanation of significant differences, update the Interim Record of Decision
(TROD) Contaminant of Concern (COC) list, remove footnotes, and establish cleanup levels for cis-1,2-
Dichloroethene and Vinyl Chloride, daughter product contaminants omitted from the IROD current list
of COCs, as well as any other unanticipated contaminants for which concentrations contribute to an
unacceptable cumulative risk that exceeds the upper bound of the risk range at 1x10-4 or Hazard Index
(HI) =1, and/or which exceed the Maximum Contaminant Limit (MCL) or risk based level if an MCL is
not available. DUE 03/29/2024

OU1 Action: Sample for the emerging contaminant 1,4-dioxane with 1,4-dioxane-specific protocols to
determine if screening levels are exceeded; and if concentrations contribute to a cumulative risk that
exceeds the risk range at 1x10-4 or HI=1, it should be added as a COC for OU1. Due 06/30/2023

OU3 Action: Resume monitoring for all OU3 Record of Decision (ROD) COCs in the next round of
sampling in the spring of 2021 so that the data can be used to determine if the remedy is functioning as
intended. DUE 10/31/2022

OU3 Action: Conduct additional studies to determine the nature and extent of contamination and, if
warranted, refine the plume boundaries at Solid Waste Management Units 8, 10, and 11. DUE 06/30/23

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0U3 Action: Complete a Non-Time Critical Removal Action (NTCRA) for Building 172 and subsurface
contamination in a timely manner. DUE 09/29/2023

OU3 Action: Continue collecting monitored natural attenuation (MNA) parameter data and complete an
MNA evaluation for RDX and TNT after the NTCRA is complete. If it is determined that MNA alone
will not meet cleanup goals in a timely manner, evaluate remedial alternatives to meet cleanup goals in a
timely manner. DUE 06/28/2024

OU3 Action: Complete an evaluation of site-specific background, geology, geochemistry, and other
potential factors to determine if the concentrations on site are naturally occurring or if additional
remedial actions are needed. If changes to the ROD COC list or corresponding cleanup levels are
warranted, follow the EPA's ROD guidance to do so and obtain approval. DUE 12/30/2022

OU3 Action: Determine which contaminant(s), especially Total Chromium and/or Hexavalent
Chromium, are appropriate for inclusion as a COC and verify appropriate cleanup levels have been
established in the ROD. DUE 12/30/2022

OU3 Action: Propose, to the EPA and the Alabama Department of Environmental Management
(ADEM) for approval, risk-based screening levels against which to evaluate RDX and TNT MNA
degradation products. DUE 12/30/2022

OU3 Action: Perform a risk screening of recent contaminant data in accordance with the EPA's FYR
guidance to identify any contaminants for which concentrations contribute to an unacceptable
cumulative risk that exceeds the upper bound of the risk range at 1x10-4 or HI=1, and/or which exceed
the MCL or risk-based level if an MCL is not available; then add identified contaminants to the ROD as
a COC with enforceable cleanup levels. DUE 03/29/2024

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