RECORD OF DECISION AMENDMENT #5

FOR

OPERABLE UNIT 2 (OU2)

NEW BRIGHTON/ARDEN HILLS SUPERFUND SITE

March 2014

FINAL

Table of Contents

TABLE OF CONTENTS .............................................................................................................. i

ACRONYMS ................................................................................................................................ iii

1.0 INTRODUCTION .......................................................................................................... 1-1

1.1 Proposed Changes in the Remedy .......................................................................... 1-1 1.2 Procedure for Changing the Remedy ...................................................................... 1-2 1.3 Public Comment Period .......................................................................................... 1-3

2.0 BACKGROUND ............................................................................................................ 2-1

2.1 Site History ............................................................................................................. 2-1 2.1.1 Site A .......................................................................................................... 2-2 2.1.2 13 5 Primerffracer Area .............................................................................. 2-2 2.1.3 EBS Areas ................................................................................................... 2-3

2.2 Engineering Evaluation/Cost Analysis and Additional Investigation .................... 2-4 2.3 Removal Action Implementation ............................................................................ 2-7

3.0 BASIS FOR THE FUNDAMENTAL CHANGE TO THE SELECTED REMEDY3-1

4.0 DESCRIPTION OF REMEDY CHANGES ................................................................ 4-1

5.0 EVALUATION OF ALTERNATIVES ....................................................................... 5-1

6.0 STATUTORY DETERMINATIONS .......................................................................... 6-1

6.1 Protection of Human Health and the Environment.. ............................................... 6-1 6.2 Compliance with ARARs ....................................................................................... 6-1 6.3 Cost Effectiveness ................................................................................................... 6-1 6.4 Utilization of Permanent Solutions and Alternative Treatment Teclmologies or

Resource Recovery Technologies to the Maximum Extent Practicable ................. 6-2 6.5 Preference for Treatment as a Principal Element .................................................... 6-2 6.6 Five-Year Review Requirements ............................................................................ 6-2

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Table of Contents (Cont.)

FIGURES

I Site Map

APPENDICES

A Responsiveness Summary B Applicable or Relevant and Appropriate Requirements C References

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AOC

ARAR

Army

BAP

CERCLA

coc cPAHs

EBS

EE/CA

ESD

FFA

LUC

LUCRD

mg/kg

MNARNG

MPCA

NB/AH

NCP

NPL ou PAHs

PTA

RAO

Rl/FS

ROD

RRG

SLV

SRV

TCAAP

TCLP

Acronyms

Area of Concern

Applicable or Relevant and Appropriate Requirements

U.S. Army

Benzo(a)Pyrene

Comprehensive Environmental Response, Compensation, and Liability Act

Chemical of Concern

Carcinogenic Polycyclic Aromatic Hydrocarbons

Environmental Baseline Survey

Engineering Evaluation/Cost Analysis

Explanation of Significant Difference

Federal Facility Agreement

Land Use Control

Land Use Control Remedial Design

Milligrams per Kilogram

Minnesota Army National Guard

Minnesota Pollution Control Agency

New Brighton/ Arden Hills

National Oil and Hazardous Substances Pollution Contingency Plan

National Priorities List

Operable Unit

Polycyclic Aromatic Hydrocarbons

Primer/Tracer Area

Removal Action Objective

Remedial Investigation/Feasibility Study

Record of Decision

Recommended Remediation Goal

Soil Leaching Value

Soil Reference Value

Twin Cities Army Ammunition Plant

Toxicity Characteristic Leaching Procedure

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USEPA

voc Wenck

Acronyms (Cont.)

U.S. Environmental Protection Agency

Volatile Organic Compound

Wenck Associates, Inc.

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1.0 Introduction

1.1 PROPOSED CHANGES IN THE REMEDY

This decision document amends the Record of Decision (ROD) for Operable Unit 2 (OU2) of the

New Brighton! Arden Hills Superfund Site (NB/ AH site). The Site, which includes the Twin

Cities Army Ammunition Plant (TCAAP), is located in Arden Hills, Minnesota. OU2 consists of

affected soil, sediment, surface water, and groundwater within the boundaries of the TCAAP

facility that were impacted by waste materials such as volatile organic compounds (VOCs),

heavy metals, and explosives as a result of site operations and/or waste management and disposal

activities that occuned in the period from 1941 to 1981. Figure 1 shows the location of TCAAP

and its boundary in 1983 (i.e., the OU2 boundary) and the location of the soil areas of concern

that are addressed in this ROD amendment, which is ROD Amendment #5 for the OU2 ROD.

The OU2 ROD was issued in 1997. ROD Amendment #1 for Site C-2 (a portion of Site C) was

finalized in 2007. ROD Amendments #2 and #3, along with Explanation of Significant

Difference (ESD) #1 and #2, were all finalized in 2009 and documented final remedies at various

soil and dun1p sites and also addressed land use controls (LUCs) at various soil, groundwater,

and dump sites. ROD Amendment #4 was finalized in 2012 and documented final remedies at

various aquatic sites, two soil sites, and Building 102 shallow groundwater. OU2 is one of three

Operable Units cunently established for the NB/ AH site. OUl addresses the North Plume of

groundwater contamination located off-TCAAP and OU3 addresses the South Plume of

groundwater contamination off-TCAAP.

Under the authority of the Comprehensive Enviromnental Response, Compensation, and

Liability Act of 1980, as amended (CERCLA), 42 U.S. C. §9601, et seq. and Executive Order

12580, the United States Army (Army) is the lead agency for response actions at the Superfund

Site. All remedial actions are subject to the provisions of the Federal Facility Agreement (1987)

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among the Army, the U.S. Environmental Protection Agency (USEPA), and the Minnesota

Pollution Control Agency (MPCA).

ROD Amendment #5 addresses soil areas of concern (AOCs) where a removal action has been

completed (Site A, 135 Primer/Tracer Area (PTA), and Environmental Baseline Survey (EBS)

Areas), and industrial use cleanup levels were met. Since the removal action has already been

implemented, Amendment #5 documents that the completed Removal Action constitutes the

final remedy for these soil areas of concern and that the only additional remedial action required

is implementation of a LUC. Hence, the selected remedy for the soil AOCs is No Further Action

with Land Use Controls, which includes a LUC to restrict property uses to those that are

compatible with the exposure assumptions used to derive the cleanup levels.

1.2 PROCEDURE FOR CHANGING THE REMEDY

Under Section 117 of CERCLA and Section 300.435( c )(2)(ii) of the National Oil and Hazardous

Substances Pollution Contingency Plan (NCP), if a new, proposed remedial action fundamentally

differs from a final ROD with respect to scope, perfonnance, or cost, the lead agency is required

to prepare an amendment to the ROD describing the changes that are to be made, stating the

reasons such changes are being made, and providing assurances that the proposed remedy

satisfies the statutory requirements. The decision to change the remedy for OU2 constitutes a

fundamental change in the OU2 remedy, necessitating the issuance of a new Proposed Plan and

an amended OU2 ROD.

This OU2 ROD amendment and all supporting documents will become part of the NB/AH site

Administrative Record file in accordance with Section 300.825(a)(2) of the NCP. The

Administrative Record is available during business hours and is located at:

Twin Cities Army Ammunition Plant Office 470 West Highway 96, Suite 100

Shoreview, MN 55126

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1.3 PUBLIC COMMENT PERIOD

In accordance with Section 300.435(c)(2)(i) of the NCP, the Army prepared a Proposed Plan and

facilitated a newspaper notice of the proposed OU2 ROD modification in January 2014. This

notice identified a 30-day public comment period that ended on February 10, 2014, and also

included an offer to hold a public meeting, if requested. No public meeting was requested and

no written comments were received during the comment period. The Responsiveness Summary

is included as Appendix A.

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2.0 Background

2.1 SITE HISTORY

The NB/ AH site consists of a 25-square mile area located in Ramsey County, Minnesota. It

includes the approximately 4-square mile area of the original TCAAP facility and portions of

seven nearby communities: New Brighton, Arden Hills, St. Anthony, Shoreview, Mounds View,

Columbia Heights, and Minneapolis.

TCAAP was constructed in 1941 to produce small-caliber ammunition for the United States

military. Production activities included manufactming small mms ammunition and related

materials, proof-testing small arms ammunition and related items as required, and handling and

storing strategic and critical materials for other government agencies. Ammunition production

and related activities have occmred periodically, commensmate with operations in wars,

conflicts, and other national emergencies, and ceased in 2005.

In 1983, the site was put on the National Priorities List (NPL) because USEPA and MPCA

determined that hazardous substances from TCAAP had been released into the enviromnent.

The NB/ AH site was divided into three operable units, as discussed in Section 1.1. Figme 1

shows the location ofTCAAP and its boundary in 1983 (i.e., the OU2 boundary) and the location

of the soil AOCs that are addressed in this ROD amendment.

Background infonnation for each of the individual sites is presented in the remainder of this

section.

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2.1.1 Site A

The area designated as Site A was reportedly used from the early 1940s to 1966 for burial and/or

burning of various wastes, such as sewage sludge, solvents, explosive-containing wastes, and

mercury crack cases, which resulted in contamination of soil and groundwater. The 1997 OU2

ROD selected excavation, stabilization, and off-site disposal for remediation of metals­

contaminated soil at Site A and, in 1998 and 1999, approximately 16,300 cubic yards of ~·,.

contaminated soil and debris were removed to achieve the cleanup levels. Refer to the "Final

Remedial Action Completion and Shallow Soils Close Out Report, Site A Activities", Stone &

Webster, December 2001. Years after completion of this remedial action work at Site A,

Minnesota Army National Guard (MNARNG) personnel observed an area that had no vegetation

located near the edge of one of the previously-excavated areas. Initial field sampling activities

were completed by the MNARNG in 2009, which confirmed the presence of metals­

contaminated soil at two soil AOCs. The two AOCs were located near the edge of a previously­

excavated area, suggesting that the previous area of excavation had needed to be slightly larger

in these two areas. The AOCs were concluded to be associated with the metals-contaminated

area that was addressed in 1998/1999 remediation work, where the chemicals of concem (COCs)

established in the OU2 ROD were antimony, barium, copper, and lead. The source of the metals

contamination appears to be the same as for the metals-contaminated areas of Site A that were

remediated in 1998/1999, i.e., TCAAP industrial operations.

2.1.2 135 Primer/Tracer Area

The 13 5 PTA was utilized for raw material storage and all aspects of manufacturing for primer

production and tracer mixing for use in TCAAP small caliber annnunition production. A

Preliminary Assessment of the 135 PTA was completed in November 2001, which recommended

that a Site Inspection be conducted. A Site Inspection Work Plan was completed in May 2002.

Initial field sampling activities were completed in 2002, which confirmed the presence of

contamination at two AOCs, designated AOC #l and AOC #2. As docmnented in the

engineering evaluation I cost analysis (EE/CA) for the soil AOCs, soil contamination was

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determined to be limited to Polycyclic Aromatic Hydrocarbons (PAHs), and no further

groundwater investigation was determined to be necessary.

The source of P AH contamination is not known. Historical documents did not identify any

industrial processes at the 135 PTA that would have been a potential source ofPAH

contamination at the site. At AOC #1, the source is most likely related to some type of

constmction material (e.g., asphaltic roofing compounds, disintegrated asphalt, etc.). At

AOC #2, the source of the P AH contamination is also unknown; however, in addition to possibly

being related to some type of construction material, it could also be related to building

demolition that was accomplished by burning the building.

2.1.3 EBS Areas

Between 1996 and 2005, EBS work was conducted by the MNARNG in anticipation of the

transfer offederal property control from TCAAP to the National Guard Bureau. Initial field

sampling activities conducted by the MNARNG during this work identified two soil areas of

concern having metals contamination. One area (AOC #1) was part of an open storage area that

had been selected for investigation based on review of aerial photographs fi·om the

Environmental Photographic Interpretation Center (EPIC) report. Photographs from 1945

through 1972 noted storage (or possible storage) of such items as debris piles, lumber, coal, and

drums. The second area (AOC #2) was a possible burning area located on a concrete

pad/loading dock. Initial sampling activities completed in 1999 indicated the two soil AOCs

were contaminated with metals/mercury. As documented in the EE/CA, no groundwater

investigation was determined to be necessary. Sampling conducted in support of the EE/CA

determined that carcinogenic PAHs (cPAHs) were also a COC at AOC #1.

The source ofmetals/PAH contamination at AOC #1 and the metals contamination at AOC #2 is

not known with certainty. AOC #I was noted as being within an open storage area evidenced in

historical aerial photographs; however, field observations detern1ined that contamination at

AOC #1 resulted from an area of shallow fill that was placed along the railroad tracks. Soils

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were noted to contain scrap metal and relatively small pieces of asphalt/concrete (corresponding

to approximately the upper 2 feet of soil). At AOC #2, the somce of the metals contamination is

unknown. A 1944 steam layout plan had labeled the concrete pad on the north edge of AOC #2

with "Bmning Kettles" and had shown two small structmes. Also, the south end of the concrete

pad is an elevated loading dock. Since AOC #2 is located at this end of the concrete pad, the

contamination may have resulted from spillage dming truck loading/unloading, possibly then

being tracked/spread through the immediate vicinity due to vehicle traffic. The highest lead

results were located immediately off the southwest comer of the pad, potentially supporting the

idea ofloading dock spillage. Also, some small caliber munitions components (casings and

projectiles, but no live rounds) were noticed within the area of soil contamination, possibly

contributing to the metals contamination. Here again, the stray components suggested general

spillage issues associated with the loading dock operations.

2.2 ENGINEERING EVALUATION/COST ANALYSIS AND ADDITIONAL

INVESTIGATION

To support preparation of the EE/CA, sampling was conducted by Wenck from March 2012

through June 2012 to define the extent and magnitude of contamination at the soil AOCs (results

were documented in the EE/CA). After the EE/CA investigation sampling was completed, and

during the time that EE/CA review/revision was occurring, the Army elected to collect additional

perimeter samples at the two EBS AOCs. Delineation of the perimeter of these two AOCs had

been considered adequate for purposes of preparing the EE/CA, but included minor gaps around

the perimeters. Hence, the EBS AOC perimeters were better defined with this additional

sampling, conducted by Wenck in September- November 2012. Results were documented in the

Removal Action Work Plan. The depths of soil contamination in the soil AOCs were generally

limited to the uppermost 1 to 2 feet of soil.

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The cleanup levels established for each soil AOC are documented in the EE/CA, and are listed

below for reference (all values are mg/kg):

Site A: Antimony 33.6

Barium 21,745

Copper 19,593

Lead 1,200

135 PTAAOC#1: cPAHs 3

Naphthalene 7.5

135 PTA AOC #2: cPAHs 3

EBS AOC #1: Lead 700

Mercury 1.5

cPAHs 3

EBS AOC #2: Antimony

Copper

Lead

Mercury

100

9,000

700

1.5

Note that cleanup levels for cPAHs are based on the MPCA's benzo(a)pyrene (BAP) equivalent

methodology. For Site A, given that the areas of concern were immediately adjacent to the prior

Site A remediation area conducted in 1998/1999, the same cleanup levels as established for the

1998/1999 work were selected for the Site A AOCs. These cleanup levels were based on a

TCAAP site-specific industrial exposure scenario. For the areas of concern at the 135 PTA and

EBS Areas, the cleanup levels were based on MPCA Industrial Soil Reference Values (SRVs),

which are risk-based human health criteria for exposure to contaminated soil under an industrial

scenario. For the 135 PTA, if the MPCA Tier 1 Soil Leaching Value (SLY) for a given

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contaminant of concern was lower than the Industrial SRV, then the SLV was used. SLVs are

based on the exposure pathway of contaminants leaching to groundwater. Groundwater is

shallow in the 13 5 PTA, and typically ranges from several feet in the western portion to at or

near the surface in the northeast portion. Hence, SLVs are applicable to the 135 PTA. SLVs

were not deemed appropriate at the EBS areas, given the presence of Unit 2 (confining layer) at

the ground surface and given the large depth to Unit 3 groundwater (approximately I 00 feet).

The EE/CA evaluated removal action alternatives for the soil AOCs. The document included the

following:

I. Summary of remedial investigations;

2. Identification of chemicals of concem (COCs);

3. Identification of removal action objectives, chemical specific applicable or relevant and

appropriate requirements (ARARs), and Recommended Remediation Goals (RRGs);

4. Description of the nature and extent of contamination in soil; and

5. Identification and evaluation of removal action alternatives that included:

a) Alternative I: No Action (Except Land Use Controls);

b) Alternative 2: Soil Cover; and

c) Alternative 3: Excavation and Offsite Disposal.

The no action altemative was included to provide a baseline alternative for comparison to other

action-oriented alternatives. These three potential alternatives were compared against each other

on the basis of effectiveness, implementability, and cost. The EE/CA recommended the

Excavation and Offsite Disposal alternative for remediation of the soil AOCs. This alternative

was noted to protect human health and the environment, meet ARARs, and accomplish the

removal action objectives (RAOs). The No Action alternative was not deemed acceptable

because it would not reliably protect human health. Excavation and Offsite Disposal was

selected over the Soil Cover alternative because, at comparable (though somewhat higher) cost,

the Excavation and Offsite Disposal alternative would not conflict with any potential future

property redevelopment of these areas (whereas the Soil Cover alternative clearly would), as

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long as that future development is consistent with the established LUC. It was also selected

because the contamination would not remain on the property, avoiding long-term soil cover

management.

The EE/CA received consistency approval by the USEPA and MPCA on November 1, 2012.

The Army published legal notices in newspapers regarding the availability of the EE/CA for

public comment and established a 30-day public comment period beginning on November 7,

2012. No comments were received. The Army selected the EE/CA-recommended remedy in an

Action Memorandum signed on December 18,2012.

2.3 REMOVAL ACTION IMPLEMENTATION

The Removal Action was completed in May-June 2013. All of the contaminated soils removed

from the AOCs were disposed of in the SKB Rosemount Industrial Waste Facility, Rosemount,

Minnesota. The total weight of contaminated soils was 1846 tons (or approximately 1230 cubic

yards, based on an estimated unit weight of 1.5 tons per cubic yard). A portion ofthese soils

(711 tons) were stabilized prior to transport to the landfill. The excavation areas were backfilled

to the approximate pre-excavation grades. The backfill material that was utilized was

commercially-available, clean common backfill and topsoil fi'om off-TCAAP sources. The

common backfill was placed and compacted to a level approximately 6 inches below the final

grade. Topsoil was then placed in the uppermost 6 inches, and then seeded to re-establish grass.

The Removal Action Completion Report documenting this work was approved by the USEP A

and MPCA on November 15,2013.

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3.0 Basis for the Fundamental Change to the Selected Remedy

The soil AOCs (Site A, 135 PTA, and EBS Areas) were not included in the OU2 ROD. A soil

removal action (Excavation and Offsite Disposal) was completed in May-June 2013, as

described in Section 2.3, which removed contaminated soils that exceeded industrial use cleanup

levels. Since the soil removal action has already been implemented, ROD Amendment #5

documents that the completed Removal Action constitutes the final remedy for these soil areas of

concern and that the only additional remedial action required is implementation of a LUC (which

technically is already in place given the "blanket" LUC described in the OU2 LUCRD). Since

cleanup levels were based on an industrial use scenario, a land use control is needed to restrict

property uses to those that are compatible with the exposure assumptions used to derive the

cleanup levels.

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4.0 Description of Remedy Changes

The soil AOCs (Site A, 135 PTA, and EBS Areas) were not included in the OU2 ROD. The

selected remedy for the soil AOCs is No Further Action with Land Use Controls, since soil

excavation and offsite disposal was previously completed in May-June 2013, as described in

Section 2.3. The LUC is:

• Restrict property use in these areas to uses that are compatible with industrial use (e.g.,

residential development would not be allowed). Technically, this LUC is already in place

given the "blanket" LUC described in the OU2 Land Use Control Remedial Design

(LUCRD).

Given that the cleanup levels were based on an industrial use scenario, the contamination levels

existing at this site will not allow for unlimited use and unrestricted exposure to soils. Hence,

CERCLA Section 121 (c) 5-year reviews and a LUC are part of the remedy for this site.

Although the "blanket" LUC already encompasses the areas of OU2 in which the soil AOCs are

located, a specific description of the soil AOCs and the LUC requirement established for this site

will also be documented in the next revision of the OU2 LUCRD.

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5.0 Evaluation of Alternatives

The soil AOCs were not included in the OU2 ROD. The "original selected remedy" was

selected in the December 2012 Action Memorandum, as discussed in Section 2.2. However, the

identified remedy had only noted the possibility that a LUC might be required if, after soil

removal was completed, soils remained onsite that exceeded the MPCA residential SRV (i.e.,

remaining soils were below the industrial cleanup levels but exceeded the MPCA Residential

SRVs). With the soil removal work now completed, it is known that some of the remaining soils

do in fact exceed the MPCA residential SRVs, and thus will require the additional remedy

component of a LUC. Hence, the evaluation of alternatives presented in this section is a

comparison of the original selected soil AOC remedy (i.e., without a definite LUC component)

against the amended remedy (No Further Action with Land Use Controls). These two

alternatives will be discussed with respect to the nine criteria specified in the CERCLA Rl/FS

guidance document (USEPA, 1988). Evaluation is based on information presented in the

Proposed Plan and the EE/CA.

I. Overall Protection of Human Health and the Environment

The soil removal action implemented alone (without a LUC) would not reliably protect

human health and the environment. Since there are soils that are above Residential SRVs

(but below industrial cleanup levels) remaining onsite, a LUC is necessary to restrict

property use in these areas to uses that are compatible with the exposure assumptions

used to derive the cleanup levels, which precludes certain property uses (e.g., residential).

The amended remedy includes this LUC.

2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)

The soil removal action implemented alone (without a LUC) would not meet ARARs.

One ARAR exists, MN Statute§ 115B.l6 (Appendix B), and it pertains to the LUC. This

ARAR requires that, for prope1ty contaminated by release of a hazardous substance, the

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property owner record (with the county recorder of the county in which the property is

located) an affidavit notifYing any potential transferee that the land was contaminated by

a release of a hazardous substance, a description of the contamination, and the nature of

property use restrictions. The amended remedy will comply with the substantive portion

of this ARAR.

3. Long-Term Effectiveness and Permanence

The soil removal action implemented alone (without a LUC) would have poor long-term

effectiveness since human health would not be reliably protected. The amended remedy

is considered to have good long-term effectiveness, given its incorporation into the OU2

LUCRD.

4. Reduction of Toxicity, Mobility, or Volume Through Treatment

The two alternatives are considered equal, given that the field work for the soil removal

action has been completed and thus no further reduction of toxicity, mobility, or volume

through treatment will occur with either alternative.

5. Short-Term Effectiveness

The two alternatives are considered equal, given that the field work for the soil removal

action has been completed and thus no short-term risk to site workers, the community,

and the environment will occur with either altemative.

6. lmplementability

The soil removal action implemented alone (without a LUC) would be slightly more

implementable, given that there would be no administrative effort being expended to

maintain the LUC. However, the additional effort to implement the LUC included in the

amended remedy is minimal, given that the same type of LUCs are being implemented at

other TCAAP sites already, and given that the OU2 LUCRD is already approved and

being implemented.

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7. Cost

The only difference in cost between the two alternatives is the additional cost of the

administrative effort to maintain the LUC associated with the amended remedy.

However, as noted above, the additional effort to implement the LUC included in the

amended remedy is minimal, given that the same type ofLUCs are being implemented at

other TCAAP sites already, and given that the OU2 LUCRD is already approved and

being implemented. This additional cost is therefore considered negligible.

8. State Acceptance

The State, with its approval of the Removal Action Completion Report on November 15,

2013, has indicated its acceptance of the amended remedy.

9. Community Acceptance

An invitation for public comment on the EE/CA and its recommended alternative

(Excavation and Offsite Disposal) was published in November 2012, which established a

30-day public comment period beginning on November 7, 2012. No comments were

received. Also, for this proposed ROD modification, the Army prepared a Proposed Plan

and facilitated a newspaper notice (which included identification of the prefened remedy

for the soil AOCs) in January 2014. This notice established a 30-day public comment

period that ended on February 10, 2014, and also included an offer to hold a public

meeting, if requested. No public meeting was requested and no written comments were

received during the comment period. With no comments received, it is concluded that

the community accepts the amended remedy (No Further Action with Land Use

Controls).

Based on the alternatives evaluation, the selected alternative for the soil AOCs (Site A, 135 PTA,

and EBS Areas) is No Further Action with Land Use Controls. This alternative protects

human health and the environment, meets ARARs, and accomplishes the RAOs. The soil

removal action implemented alone (without a LUC) was not deemed acceptable because it would

not reliably protect human health aJ1d the environment.

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6.0 Statutory Determinations

This section discusses how the remedy for the soil AOCs (Site A, 135 PTA, and EBS Areas)

meets the five statutory requirements established by Section 121 of CERCLA.

6.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT

The amended remedy protects human health by including a LUC to restrict property use in tbese

areas to uses that are compatible with the exposure assumptions used to derive the cleanup levels

(e.g., industrial use), which precludes certain property uses tbat would not be adequately

protected (e.g., residential).

6.2 COMPLIANCE WITH ARARS

The amended remedy complies with ARARs, which are identified in Appendix B.

6.3 COST EFFECTIVENESS

The amended remedy is a cost-effective method for addressing the shallow soil contamination at

the soil AOCs, i.e., the soils having contamination levels that are between the MPCA Residential

SRV s and the industrial cleanup levels.

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6.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE

TREATMENT TECHNOLOGIES OR RESOURCE RECOVERY

TECHNOLOGIES TO THE MAXIMUM EXTENT PRACTICABLE

The amended remedy was selected, in part, due to its permanent nature. The remedy removed

contamination exceeding the selected industrial cleanup levels for each AOC and does not

conflict with any potential future property redevelopment of these areas, as long as that future

development is consistent with the established LUC.

6.5 PREFERENCE FOR TREATMENT ASAPRINCIPALELEMENT

The original selected remedy (the soil removal action) included treatment of some of the

contaminated soils (i.e., use of a stabilizing agent for metals); however, the treatment component

is not applicable to the amended remedy, since the field work has already been completed.

6.6 FIVE-YEAR REVIEW REQUIREMENTS

For the soil AOCs (Site A, 135 PTA, and EBS Areas), because the remedy will result in

hazardous substances, pollutants, or contaminants remaining onsite above levels that allow for

unlimited use and unrestricted exposure, CERCLA Section 121(c) 5-year reviews will be

required for this site.

6-2 T:\1561 TCAAP\OU2\2014 ROD Amendment\Te:>.1\0U2 ROD Amend #S_Fina!.doc

Chief, Operational Army and Medical Branch Base Realigmnent & Closure Division

Richard C. Karl Director, Superfund Division U.S. Enviromnental Protection Agency, Region 5

Kathryn Sather Director, Remediation Division Minnesota Pollution Control Agency

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6-3

Date

Date

t~ 3, c::roJ'/ Date

Figures

Notes: 1. AOC =Area of Concern 2. "BAP" means MPCA's BAP Equivalent methodology 3. 2012Aerial Photograph (Source: ESRI)

2,000 1,000 0 -- 2,000

Feet ---N

A OU2 ROD AMENDMENT #5

Site Map

______..

Operable Unit 2 of the New Brighton/ Arden Hills Superfund Site (the same

Cl area occupied by The Twin Cities Army Ammunition Plant in 1983, when the Site was placed on the NPL.)

• Soil Boring Locations (original samples that indicated contamination , which was excavated in the Removal Act ion)

General location of site (see note below)

(Note: The site boundaries are only intended to illustrate the general locations and should not be interpreted as representing areas of contamination.)

Wenck MAR 2014 Engineers · Scientists 1800 Pioneer Creek Center Business Professionals Maple Plain, MN 55359-0429 www.wenck.com 1-800-472-2232

Figure 1

Appendix A

Responsiveness Summary

Responsiveness Summary

The Army prepared a Proposed Plan and facilitated a newspaper notice of the proposed OU2 ROD modification in January 2014. This notice identified a 30-day public comment period that ended on February I 0, 2014, and also included an offer to hold a public meeting, if requested. No public meeting was requested and no comments were received during the comment period.

AppendixB

Applicable or Relevant and Appropriate Requirements

Summary of ARARs for Soil AOCs (Site A, 135 PTA, EBS Areas)

ARAR ARAR Regulating Typel'l Agency

Rule Selected Remedy: No Further Action with Land Use Controls

Land Use Controls Action MPCA MN Statute§ 1158.16 ARAR, since land use controls are required for limiting land uses to those that are compatible

with industrial use. (applicable)

Notes:

1) ARAR Types: Action = Action-Specific Chemical ::::: Chemical-Specific Location :;:;: Location-Specific

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Appendix C

References

References

Alliant Techsystems, Inc., December 2001. Final Preliminary Assessment, 135 Primer/Tracer Area.

Alliant Techsystems, Inc., March 2002. Site Inspection Work Plan, Field Sampling Plan, Site Specific Health and Safety Plan, 135 Primer/Tracer Area.

EnecoTech Midwest, Inc., January 2005. Summary Report for 135 Primer/Tracer Area Site Inspection Investigation. (Revised by Tecumseh/Wenck Installation Support Services and Alliant Techsystems, Inc.)

Federal Facility Agreement. August 12, 1997.

Minnesota Pollution Control Agency, May 1998. Draft Guidelines: Risk-Based Guidance for the Soil Leaching Pathway, Users Guide.

Minnesota Pollution Control Agency, September 1998. Draft Guidelines: Risk-Based Site Characterization and Sampling Guidance.

Minnesota Pollution Control Agency, January 1999. Draft Guidelines: Risk-Based Guidance for the Soil- Human Health Pathway, Volume 2, Technical Support Document.

Mi1mesota Pollution Control Agency, June 2011. Remediation Division Policy on Analysis of Carcinogenic Polynuclear Aromatic Hydrocarbons (cP AH).

Montgomery Watson, March 1997. Operable Unit 2 Feasibility Study.

Montgomery Watson, December 1999. Final Training Area F Addendum, Phase II Environmental Baseline Survey.

Stone & Webster, Inc., December 2001. Final Remedial Action Completion and Shallow Soils Close Out Report, Site A Activities.

Twin Cities Army Ammunition Plant, New Brighton/Arden Hills Superfund Site, Operable Unit 2, Record of Decision. 1997.

U.S. Army, December 2012. Action Memorandum- Non-Time Critical Removal Action for Soil Areas of Concern (Site A, 135 Primer/Tracer Area, EBS Areas), New Brighton/Arden Hills Supe1jund Site.

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U.S. Environmental Protection Agency, October 1988. Guidance for Conducting Remedial Investigations and Feasibility Studies under CERCLA.

U.S. Environmental Protection Agency, August 1993. Guidance on Conducting Non-Time­Critical Removal Actions under CERCLA.

Wenck Associates, Inc., June 2011. Operable Unit 2 (OU2) Land Use Control Remedial Design (LUCRD). Revision 2.

Wenck Associates, Inc., January 2012. Quality Assurance Project Plan for Engineering Evaluation/Cost Analysis Soil Investigations, Site A- AOCs, 135 Primer/Tracer Area­AOCs, EBS- AOCs. Revision 2.

Wenck Associates, Inc., November 2012. Engineering Evaluation I Cost Analysis for Soil Investigations at Areas of Concern, Site A, 135 Primer/Tracer Area, EBS Areas.

Wenck Associates, Inc., March 2013. Removal Action Work Plan, Soil Areas of Concern, Site A, 135 Primer/Tracer Area, EBS Areas.

Wenck Associates, Inc., November 15, 2013. Removal Action Completion Report for Soil Areas of Concern, Soil Areas of Concern, Site A, 135 Primer/Tracer Area, EBS Areas.

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