EPA/ROD/R07-00/105
2000

EPA Superfund
Record of Decision:

CORNHUSKER ARMY AMMUNITION PLANT
EPA ID: NE2213820234
OU 03
HALL COUNTY, NE
12/14/1999

 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION VII
901 NORTH 5TH STREET
KANSAS CITY, KANSAS 66101

January 20, 2000

Ms. Angie Wright
U.S. Environmental Protection Agency
Superfund Docket (5202G)
401 M Street SW
Washington, DC 20460
Dear Ms. Wright:
Enclosed is the Record of Decision for Cornhusker Army Ammunition Plant, Operable Unit 3,
Grand Island, Nebraska.
Please let me know if you have any questions. I may be reached at (913) 551-7659.

Enclosure

 US Army Corps
of Engineers
Omaha District

Delivery Order No. DA01
Total Environmental
Program Support
Contract Number
DAAA15-91-D-0014

CORNHUSKER ARMY AMMUNITION PLANT

Record of Decision for Remedial Action
Operable Unit Three

FINAL DOCUMENT
October 1999
THIS DOCUMENT IS INTENDED TO COMPLY WITH THE NATIONAL ENVIRONMENTAL POLICY ACT OF 1969

  eecumemmlew PAGE 31:3? ewe?

 



 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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mun-r use em. 5* 11am Eleni; 1. 9mm DATE Pu we we Defer?entree en
Dumber 1999 Flemre el' DECIEICIFI {1999}
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Operable Unit Three Final Decement Gumtree: Ne.
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AUTHUFIEEI Delwery Order DEM
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a. THEM EMT 1W

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1.1 AEETHABT {Maximum zed unreal

Thus Flecerd el' Dec-reien prewdee the preterrecl remedial allemelivee for areas el enneern ?ee: hated as Operable leq
Three the Nltrate three: Pislel Flange. Eh?? Area. and the Sentlary Land?ll}. The pre erred allernetwe fer the
Shop ArEa I5 Heat-ration. Demeal el Lead?mntammaled Smile. and Memterlng In: HaIurei A?enua?un e1 
Drganics In grnundwater- The preterred alternative for Ihe Ear-Harv Land?ll re Ema-Italian and [Ill-site Dlspeeal ef FIDE-
centerr-Inatecl sell. The preterted allemelwe Ier the Pistol Flange IS Excavation and ?ll-slte Disposal of Leed- and FIDE-
cuntamineted sell- The preferred altarnelhre ter Ihe Nilrale Area is Excauetlen and Dll-eule n1 Lead-murammargd
sell. All alternalwes Inulu?e a Heed In} prewar-I reeident'rel use.

 

u. SEEJEET TERMS 15. HUHEEH eF PM. EE

Preterred Alternet'ruee, Eneevetlen. NetLJrel Attenuatignl Organics. EJQFDENEE.
FllIJI'tr Lead. Deed 

 

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anemia WW0 1a. A . WW. LIFITI ATICIH an: AB 5mm"
eF newer m: me use or ABETHAET
UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED None
rem-m-aau-ssan atmam Form Eva-H lie-e 

hunt-?m HEI 

RECORD OF DECISION FOR REMEDIAL ACTION
OPERABLE UNIT 3
CORNHUSKER ARMY AMMUNITION PLANT, NEBRASKA
FINAL DOCUMENT

Prepared by:
IT CORPORATION
2113 EMMORTON PARK ROAD
EDGEWOOD, MARYLAND 21040
OCTOBER 1999

 TABLE OF CONTENTS
Section
1.0

Page
DECLARATION OF THE RECORD OF DECISION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1
1.2
1.3
1.4
1.5
1.6

2.0

3.4

4.2

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1-1
1-1
1-1
1-1
1-2
1-2

SITE NAME, LOCATION, AND DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

FACILITY HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ENFORCEMENT ACTIVITIES . . . . . . . . . . . . . . . . . . . . . . . . . . .
ENVIRONMENTAL INVESTIGATIONS AND REMEDIAL ACTIONS
3.31
Environmental Studies at CHAAP . . . . . . . . . . . . . . . . . .
3.3.2 Remedial actions at CHAAP . . . . . . . . . . . . . . . . . . . . . .
HIGHLIGHTS OF COMMUNITY PARTICIPATION . . . . . . . . . . . . .

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3-1
3-1
3-1
3-1
3-3
3-3

HUMAN HEALTH RISKS
4.1.1 Soil COPCs . . .
4.1.2 Groundwater . . .
ECOLOGICAL RISK . . .
4.2.1 Nitrate Area . . .
4.2.2 Pistol Range . . .
4.2.3 Sanitary Landfill .
4.2.4 Shop Area . . . .

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4-1
4-2
4-3
4-5
4-5
4-5
4-5
4-5

REMEDIAL ACTION OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1
5.2
5.3

6.0

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SUMMARY OF SITE RISKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1

5.0

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HISTORY AND ENFORCEMENT ACTIVITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.1
3.2
3.3

4.0

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DECISION SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.1

3.0

SITE NAME AND LOCATION . . . . . . . . . . . . .
STATEMENT OF BASIS AND PURPOSE . . . .
ASSESSMENT OF HE SITE . . . . . . . . . . . . .
DESCRIPTION OF THE SELECTED REMEDY
STATUTORY DETERMINATIONS . . . . . . . . . .
ROD DATA CERTIFICATION CHECK LIST . . . .

REMEDIAL ACTION OBJECTIVES FOR SOIL . . . . . . . . . .
5.1.1 Methodology for Calculating COPC Cleanup Levels .
REMEDIAL ACTION OBJECTIVES FOR GROUNDWATER .
5.2.1 Groundwater Cleanup Level . . . . . . . . . . . . . . . . .
NATURALLY OCCURRING COPCs . . . . . . . . . . . . . . . . . .
5.3.1 Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.2 Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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5-1
5-1
5-4
5-4
5-6
5-6
5-7

NITRATE AREA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.1
6.2
6.3

6.4

OPERATIONAL HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
FINDINGS OF THE REMEDIAL INVESTIGATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.2.1 Groundwater Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.2.2 Soil Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
DESCRIPTION OF ALTERNATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.3.1 Alternative One: No Action for the Nitrate Area . . . . . . . . . . . . . . . . . . . . . . 6-1
6.3.2 Alternative Two: Excavation, Off-Site Disposal of Lead-Contaminated Soil for the
Nitrate Area, and Deed restriction to Prevent Residential Use . . . . . . . . . . . . 6-4
SUMMARY OF ANALYSIS FOR THE NITRATE AREA ALTERNATIVES . . . . . . . . . . 6-5
6.4.1 Protection of Human Health and the Environment . . . . . . . . . . . . . . . . . . . . . 6-5
6.4.2 Compliance with ARARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
6.4.3 Long-term Effectiveness and Permanence . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6

DAAA15-91-D-0014
TEPS14-14
October 1999

i

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Table of Contents
(Continued)

6.5
6.6
7.0

6.4.4 Reduction of Toxicity, Mobility or Volume through Treatment
6.4.5 Short-term Effectiveness . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.6 Implementability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.7 Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SELECTED REMEDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EXPLANATION OF SIGNIFICANT CHANGES . . . . . . . . . . . . . . . .

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6-6
6-6
6-7
6-7
6-7
6-7

PISTOL RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
7.1
7.2
7.3

7.4

7.5
7.6

OPERATIONAL HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
FINDINGS OF THE REMEDIAL INVESTIGATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
7.2.1 Soil Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
DESCRIPTION OF ALTERNATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
7.3.1 Alternative 1: No Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
7.3.2 Alternative 2: Deed Restriction and Groundwater Monitoring . . . . . . . . . . . . . 7-4
7.3.3 Alternative 3: Excavation and Off-site Disposal of Soil from Test Trenches PRST07
and PRST08 and Deed Restriction to Prevent Residential Use . . . . . . . . . . . . 7-5
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES FOR THE PISTOL
RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6
7.4.1 Protection of Human Health and the Environment . . . . . . . . . . . . . . . . . . . . 7-8
7.4.2 Compliance with ARARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
7.4.3 Long-term Effectiveness and Permanence . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
7.4.4 Reduction of Toxicity, Mobility or Volume through Treatment . . . . . . . . . . . . . 7-8
7.4.5 Short-term Effectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9
7.4.6 Implementability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9
7.4.7 Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9
SELECTED REMEDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9
EXPLANATION OF SIGNIFICANT CHANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10

8.0 SANITARY LANDFILL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
8.1
8.2
8.3

8.4

8.5
8.6
9.0

OPERATIONAL HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
FINDINGS OF THE REMEDIAL INVESTIGATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
REMEDIAL ALTERNATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
8.3.1 Alternative 1: No Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
8.3.2 Alternative 2: Groundwater Monitoring and Deed Restriction . . . . . . . . . . . . . 8-4
8.3.3 Alternative 3: Excavation, Off-Site Disposal of RDX-Contaminated Soil, and Deed
Restriction to Prevent Residential Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4
SUMMARY OF COMPARATIVE ANALYSIS OF SANITARY LANDFILL
ALTERNATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-5
8.4.1 Protection of Human Health and Environment . . . . . . . . . . . . . . . . . . . . . . . . 8-6
8.4.2 Compliance with ARARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
8.4.3 Long-term Effectiveness and Permanence . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
8.4.4 Reduction of Toxicity, Mobility or Volume through Treatment . . . . . . . . . . . . . 8-7
8.4.5 Short-term Effectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
8.4.6 Implementability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
8.4.7 Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8
SELECTED REMEDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-8
EXPLANATION OF SIGNIFICANT CHANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9

SHOP AREA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
9.1
9.2
9.3
9.4

OPERATIONAL HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FINDINGS OF THE REMEDIAL INVESTIGATION . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.1 Groundwater Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.2.2 Building S-22, Building S-37, and Laundry Settling Basin Sampling Results
CONTAMINANT FATE AND TRANSPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REMEDIAL ALTERNATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.4.1 Alternative 1: No Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DAAA15-91-D-0014
TEPS14-14
October 1999

ii

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9-1
9-1
9-1
9-4
9-4
9-5
9-5

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Table of Contents
(Continued)

9.4.2

9.5

9.6
9.7
10.0

RESPONSIVENESS SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10.1

11.0

Alternative 2: Soil Excavation, Long-term Monitoring for Natural Attenuation of
Chlorinated Organic Compounds in Groundwater, and Deed Restriction . . . . . 9-6
9.4.3 Alternative 3: Soil Excavation, Liquid-Phase Carbon Adsorption, and Deed
Restriction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9
9.4.4 Alternative 4: Soil Excavation, Air Stripping, and Deed Restriction . . . . . . . . 9-10
SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES FOR THE SHOP
AREA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-12
9.5.1 Protection of Human Health and Environment . . . . . . . . . . . . . . . . . . . . . . . 9-14
9.5.2 Compliance with ARARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14
9.5.3 Long-term Effectiveness and Permanence . . . . . . . . . . . . . . . . . . . . . . . . . 9-14
9.5.4 Reduction of Toxicity, Mobility or Volume through Treatment . . . . . . . . . . . . 9-15
9.5.5 Short-term Effectiveness
9-15
9.5.6 Implementability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15
9.5.7 Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15
SELECTED REMEDY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-15
EXPLANATION OF SIGNIFICANT CHANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-17

OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DAAA15-91-D-0014
TEPS14-14
October 1999

iii

11-1

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 LIST OF EXHIBITS
Exhibit
2-1

Operable Unit Designations at CHAAP

6-1

Sample Locations, Nitrate Area

6-2

Nitrate Area, Location of COPC Detected Above Cleanup Level

6-3

Nitrate Area, Preferred Alternative: Alternative 2 (Excavation, Off-Site Disposal of Lead
Contaminated Soil, and Deed Restriction to Prevent Residential Use)

7-1

Sample Locations, Pistol Range

7-2

Pistol Range, Locations of COPCs Detected Above Cleanup Levels

7-3

Pistol Range, Preferred Alternative: Alternative 3 (Excavation of Test Trenches PRST07 and
PRST08, Off-Site Disposal, and Deed Restriction to Prevent Residential Use

8-1

Sample Locations, Sanitary Landfill

8-2

Sanitary Landfill, Locations of COPC Detected Above Cleanup Level

8-3

Sanitary Landfill, Preferred Alternative: Alternative 3 (Excavation, Off-Site Disposal of RDX
Contaminated Soil, and Deed Restriction to Prevent Residential Use

9-1

Sample Locations, Shop Area

9-2

Shop Area, Locations Where Groundwater COPCs Exceeded Cleanup Levels, 1995, 1996, and
1998

9-3

Shop Area, Preferred Alternative: Alternative 2 (Soil Excavation and Long-Term Monitoring for
Natural Attenuation of Chlorinated Organic Compounds in Groundwater)

DAAA15-91-D-0014
TEPS14-14
October 1999

iv

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 LIST OF TABLES
Table
4-1

COPCs in Surface Soil for Human Receptors at the CHAAP OU3 Areas

4-2

COPCs in Sub-Surface Soil for Human Receptors at the CHAAP OU3 Areas

4-3

Chemicals of Potential Concern in Groundwater at CHAAP

4-4

Exposure Pathways Evaluated in the HHRA

5-1

Cleanup Levels for Soil COPCs ( µg/g) at the Nitrate Area

5-2

Cleanup Levels for Soil COPCs ( µg/g) at the Pistol Range

5-3

Cleanup Levels for Soil COPCs ( µg/g) at the Sanitary Landfill

5-4

Cleanup Levels for Soil COPCs ( µg/g) at the Shop Area

5-5

Cleanup Levels for Groundwater COPCs ( µg/L) at CHAAP

5-6

Comparison of Various Concentrations of Arsenic with Risk-Based Cleanup Levels

5-7

Comparison of Beryllium Concentrations and Calculated Risk-Based Cleanup Levels

6-1

Comparative Analysis of Remedial Action Alternatives – Nitrate Area

6-2

Cost Estimate for Preferred Alternative for Excavation, Off-Site Disposal of Lead-Contaminated Soil,
and Deed Restrictions for Non-Residential Use

6-3

Action-Specific ARARs for Preferred Alternative: Excavation, Off-Site Disposal of Lead
Contaminated Soil, and Deed Restrictions for Non-Residential Use

6-4

Location-Specific ARARs for Preferred Alternative: Excavation, Off-Site Disposal of Lead
Contaminated Soil, and Deed Restrictions for Non-Residential Use

6-5

Chemical-Specific ARARs/TBC Guidance for Preferred Alternative: Excavation, Off-Site Disposal of
Lead-Contaminated Soil, and Deed Restrictions for Non-Residential Use

7-1

Comparative Analysis of Remedial Action Alternatives - Pistol Range

7-2

ARARs and TBC Guidance for Preferred Alternative for Excavation, Off-Site Disposal of Lead
Contaminated Soil, and Deed Restrictions for Non-Residential Use

7-3

Cost Estimate for Preferred Alternative for Excavation, Off-Site Disposal of Lead-Contaminated Soil,
and Deed Restrictions for Non-Residential Use

8-1

Comparative Analysis of Remedial Action Alternatives - Sanitary Landfill

8-2

ARARs and TBC Guidance for Alternative 3

8-3

Cost Estimate for Alternative 3

9-1

Comparative Analysis of Remedial Action Alternatives - Shop Area

9-2

ARARs and TBC Guidance for Alternative 2

9-3

Cost Estimate for Alternative 2

10-1

Summary of Preferred Remedial Alternatives for OU3

DAAA15-91-D-0014
TEPS14-14
October 1999

v

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 LIST OF ACRONYMS AND ABBREVIATIONS

AOC . . . . . . . . .
ARAR . . . . . . .
AST . . . . . . . .
bgs . . . . . . . .
CERCLA . . . . .
CHAAP . . . . . .
CLP . . . . . . . . .
COPC . . . . . . .
EA . . . . . . . . . .
EEI . . . . . . . . .
EPIC . . . . . . . .
ERA . . . . . . . . .
FFA . . . . . . . . .
ft . . . . . . . . . . .
GAC . . . . . . . . .
GOCO . . . . . . .
gpm . . . . . . . . .
HEAST . . . . . . .
HHRA . . . . . . . .
HI . . . . . . . . . . .
IEUBK . . . . . . .
IRA . . . . . . . . .
IRIS . . . . . . . . .
Mason & Hanger
MCL . . . . . . . . .
NCP . . . . . . . . .
NDEQ . . . . . . .
NPDES . . . . . .
O&M . . . . . . . .
OU . . . . . . . . . .
OU1 . . . . . . . . .
OU2 . . . . . . . . .
OU3 . . . . . . . . .
OU4 . . . . . . . . .
OU5 . . . . . . . . .
PAH . . . . . . . . .
PUC . . . . . . . . .
PVC . . . . . . . . .
RAO . . . . . . . . .
RCRA . . . . . . . .
RI/FS . . . . . . . .
ROD . . . . . . . . .
SARA . . . . . . . .
SCD . . . . . . . . .
SOP . . . . . . . . .
TBC . . . . . . . . .
TCL . . . . . . . . .
TCLP . . . . . . . .
TRV . . . . . . . . .
USACE . . . . . .
USAEC . . . . . .
USAEHA . . . . .
USATHAMA . . .
DAAA15-91-D-0014
TEPS14-14
October 1999

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Area of Concern
applicable or relevant and appropriate requirement
aboveground storage tank
below ground surface
Comprehensive Environmental Response, Compensation, and Liability Act of 1980
Cornhusker Army Ammunition Plant
Contract Laboratory Program
chemical of potential concern
Excessing Assessment
Envirodyne Engineers, Inc.
Environmental Photographic Interpretation Center
ecological risk assessment
Federal Facility Agreement
foot/feet
granular activated carbon
government-owned, contractor-operated
gallons per minute
Health Effects Assessment Summary Tables
human health risk assessment
hazard index
Integrated Exposure Uptake/Biokinetic
interim soil removal action
Integrated Risk Information System
Mason & Hanger-Silas Mason Company
Maximum Contaminant Level
National Oil and Hazardous Substances Pollution Contingency Plan
Nebraska Department of Environmental Quality
National Pollutant Discharge Elimination System
operation and maintenance
operable unit
Operable Unit One
Operable Unit Two
Operable Unit Three
Operable Unit Four
Operable Unit Five
polycyclic aromatic hydrocarbon
Potential Unit of Contamination
polyvinyl chloride
remedial action objective
Resource Conservation and Recovery Act
Remedial Investigation/Feasibility Study
Record of Decision
Superfund Amendments and Reauthorization Act of 1986
Site Characterization Document
Standard Operating Procedure
To-Be-Considered
Target Compound List
Toxicity Characteristic Leaching Procedure
Toxicity Reference Value
U.S. Army Corps of Engineers
U.S. Army Environmental Center
U.S. Army Environmental Hygiene Agency
U.S. Army Toxic and Hazardous Materials Agency
vi

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 List of Acronyms and Abbreviations
(Continued)

USEPA
UST . . .
UXO . . .
VOC . . .
XRF . . .

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DAAA15-91-D-0014
TEPS14-14
October 1999

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U.S. Environmental Protection Agency
underground storage tank
unexploded ordnance
volatile organic compound
x-ray fluorescence

vii

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 1.0

DECLARATION OF THE RECORD OF DECISION

1.1

SITE NAME AND LOCATION
Cornhusker Army Ammunition Plant (CHAAP), Grand Island, Nebraska.

1.2

STATEMENT OF BASIS AND PURPOSE

This Record of Decision (ROD) document presents the selected remedial action(s) for Operable Unit
Three (OU3) comprising of the Nitrate Area, Pistol Range, Sanitary Landfill, and Shop Area, located at the
CHAAP in Grand Island, Nebraska. The remedial action was selected in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by the Superfund
Amendments and Reauthorization Act of 1986 (SARA), and, to the extent practicable, with the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP). The information supporting the decisions on the
selected remedies is contained in the Administrative Record.
The U.S. Environmental Protection Agency (USEPA) and the Nebraska Department of Environmental
Quality (NDEQ) concur with the selected remedy.
1.3

ASSESSMENT OF THE SITE

The response actions selected in this ROD for the Areas of Concern (AOCs) designated as OU3 (i.e.,
Nitrate Area, Pistol Range, Sanitary Landfill, and the Shop Area), are necessary to protect the public health
or welfare or the environment from actual or threatened releases of hazardous substances into the environment.
1.4

DESCRIPTION OF THE SELECTED REMEDY

This ROD has been developed for OU3, which includes the Nitrate Area, Pistol Range, Sanitary
Landfill, and the Shop Area. The cleanup levels for OU3 were developed based on protection of industrial
workers. The following preferred remedies for each AOC provide protection to humans under non-residential
conditions.
Nitrate Area:
The alternative that has been selected as the preferred remedy for protecting human health under
non-residential conditions at the Nitrate Area consists of excavation, off-site disposal of lead contaminated soil,
and deed restriction to prevent residential use.
Pistol Range:
The alternative that has been selected as the preferred remedy for protecting human health under
non-residential conditions at the Pistol Range consists of excavation, off-site disposal of RDX- and leadcontaminated soil, and deed restriction to prevent residential use.
Sanitary Landfill:
The alternative that has been selected as the preferred remedy for protecting human health under
non-residential conditions at the Sanitary Landfill consists of excavation, off-site disposal of RDX contaminated
soil, and deed restriction to prevent residential use.
Shop Area:
The alternative that has been selected as the preferred remedy for protecting human health under
non-residential conditions at the Shop Area consists of the following:
•

Excavation, off-site disposal of lead-contaminated soil, and deed restriction to prevent residential
use.

•

Long-term monitoring for natural attenuation of chlorinated organic compounds in groundwater and
deed restriction to prevent groundwater use.

The deed restrictions will include proprietary institutional controls restricting the future use of the
property such as easements or restrictive covenants that are legally enforceable against subsequent
DAAA15-91-D-0014
TEPS14-14
October 1999

1-1

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 1.0
Declaration of the Record of Decision

property owners and instituted, depending on state law, by conveyance or contract. The U.S. Army will be
responsible for implementing and maintaining the effectiveness of institutional controls.
1.5

STATUTORY DETERMINATIONS

The selected remedies are protective of human health and the environment, comply with Federal and
state requirements that are applicable or relevant and appropriate to the remedial action, are cost-effective, and
utilize permanent solutions to the maximum extent practicable.
The remedies in this OU do not satisfy the statutory preference for treatment (other than any treatment
used as part of off-site disposal) as a principal element of the remedy due to the limited extent of soil
contamination identified at the AOCs designated as OU3.
Because this remedy will result in hazardous substances, pollutants, or contaminants remaining onsite
above levels that allow for unlimited use and unrestricted exposure, a statutory review will be conducted within
five years after initiation of remedial action to ensure that the remedy is, or will be, protective of human health
and the environment.
1.6

ROD DATA CERTIFICATION CHECK LIST

The following information is included in this ROD. Additional information can be found in the
Administrative Record file for this site.
•

Chemicals of potential concern (COPCs) (Section 4)

•

Baseline risk represented by the COPCs (Section 4)

•

Cleanup levels established for COPCs and the basis for these levels (Section 5)

•

How source materials constituting principal threats are addressed (Sections 6, 7, 8, and 9)

•

Current and reasonably anticipated future land use assumptions and current and potential future
beneficial uses of groundwater used in the baseline risk assessment and ROD (Section 4)

•

Potential land and groundwater use that will be available at the site as a result of the Selected
Remedies (Sections 6, 7, 8, and 9)

•

Estimated capital, annual operation and maintenance (O&M), and total present worth costs,
discount rate, and the number of years over which the remedy cost estimates are projected
(Sections 6, 7, 8, and 9)

•

Key factors that led to selecting the remedies (Section 6, 7, 8, and 9)

DAAA15-91-D-0014
TEPS14-14
October 1999

1-2

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 1.0
Declaration of the Record of Decision

DAAA15-91-D-0014
TEPS14-14
October 1999

1-3

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 2.0

DECISION SUMMARY

2.1

SITE NAME, LOCATION, AND DESCRIPTION

Cornhusker Army Ammunition Plant is located on an 11,936-acre (19 square miles) tract approximately
two miles west of Grand Island, Nebraska, in north-central Hall County.
The land around CHAAP is intensely cultivated and row crops, such as corn and alfalfa, have replaced
most of the original prairie grass and other vegetation. Most of the land between CHAAP and Grand Island is
used for farming, predominately for hay and/or pasture, dryland crops, and irrigated corn, alfalfa, and soybeans.
A large portion of CHAAP is inactive; however, much of the land and buildings are leased to various
individuals and local concerns. Approximately 10,774 acres (17 square miles) is leased out for general
agricultural use as follows: 82% cropland, 15% wildlife habitat and protection areas, and 3% grazing. The
majority of the cropland acreage is irrigated. Eighty-eight magazines and 25 other buildings are leased out as
general storage space.
CHAAP has been divided into five operable units (OUs) (Exhibit 2-1) based on land use and the extent
of remedial action required for protecting human health and the environment.
Operable Unit One (OU1) is comprised of the explosives-contaminated groundwater plume, which
originates from the Load Line Buildings 1-5. An interim ROD has been completed for OU1 and a pump-and-treat
system is currently on-line. The pump-and-treat system consists of six extraction wells with a total estimated
groundwater extraction rate of approximately 700 gallons per minute, sand filters, and a carbon adsorption
system.
The Administration and Base Housing Areas, Abandoned Burning Area, Drainage Ditches, Magazine
Areas, Miscellaneous Storage Areas, and Sewage Treatment Plants comprise Operable Unit Two (OU2). A
ROD for no further remedial action has been completed for OU2 (1998).
Operable Unit Four (OU4) is comprised of the Gravel and Clay Pits and the unsaturated zone (0-6 feet
[ft] below ground surface [bgs]) of Load Lines 1-5. Operable Unit Five (OU5) consists of the Burning Grounds.
The Burning Grounds was designated as OU3 in the Feasibility Study. However, because the Army does not
want to continue restrictions on the property due to unexploded ordnance (UXO), the AOC has been removed
from OU3 and redesignated as OU5. A ROD will be completed for the Burning Grounds.
This ROD has been prepared for OU3, which includes the Nitrate Area, Pistol Range, Sanitary Landfill,
and Shop Area.
The Nitrate Area is located in the southeast part of the installation, between the Shop Area and the
Administration Area. The Nitrate Area has historically been used to produce crystalline nitrate for bomb
production and ammonium nitrate for fertilizer. Cornhusker Railroad Services is a railcar refurbishing operation
that has leased and operated much of the Nitrate Area since 1979. The leased areas include Building N-17, the
railcar loading area, adjacent open storage areas, and rail sidings throughout CHAAP.
The Pistol Range is located near the western boundary of CHAAP. The site covers approximately 30
acres and currently contains a large earthen backstop berm. A small-arms firing range is located on the south
side of the berm, and is surrounded by cultivated fields. This area has historically been used as a small arms
training area for state and local police authorities. During the 1968-1969 time period, portions of the Pistol
Range were also used for the destruction and burning of wastes from Load Line 5. Local law enforcement
personnel currently use the Pistol Range for small-arms practice/training. The adjacent fields are leased out
for dry crop cultivation.
The Sanitary Landfill is located in the northwest section of the installation, southeast of the Burning
Grounds, and southwest of the intersection of Ninth Avenue and Tenth Street. It encompasses an area of
approximately 55 acres. The Sanitary Landfill includes the Sanitary Waste Disposal, Capped Landfill, Burning
Cages Metals Disposal, Flammable Liquids Disposal, Fuse Destruction, Interim Removal Site 2, and the
Explosives Parking Areas.

DAAA15-91-D-0014
TEPS14-14
October 1999

2-1

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

  

 

 

 

 

   
   

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Section 2.0
Decision Summary

The Shop Area, located in the east-central area of the facility, immediately south of Load Line 1, covers
an area of about 3,000,000 ft 2 and includes 28 buildings and sheds. The Shop Area consists of the installation
laundry and a settling basin for laundry wastewater; maintenance facilities for vehicles, equipment and other
operations; rail loading and unloading areas; and open storage areas.

DAAA15-91-D-0014
TEPS14-14
October 1999

2-3

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 3.0

HISTORY AND ENFORCEMENT ACTIVITIES

3.1

FACILITY HISTORY

The CHAAP was constructed and fully operational in 1942. The CHAAP was a U.S. government-owned,
contractor-operated (GOCO) facility, which produced artillery shells, mines, bombs, and rockets for World War
II, Korean, and Vietnam conflicts. The plant was operated intermittently for 30 years; the most-recent operations
ending in 1973.
Quaker Oats Ordnance Corporation, a subsidiary of the Quaker Oats Company that produced bombs,
shells, boosters, and supplementary charges, operated the plant from 1942 through 1945. The plant was on
standby status for munitions production from 1945 through 1950. During the standby period, many of the
buildings were also used for grain storage.
The plant was reactivated in 1950 to produce artillery shells and rockets to support the Korean conflict.
These operations were directed by Mason & Hanger-Silas Mason Company (Mason & Hanger) until 1957 when
the plant was again placed on standby status (USATHAMA, 1980). In 1963, a total of 809 acres from three
parcels of land situated in the northeast, northwest, and southeast corners of the facility were sold to the State
of Nebraska for use as wildlife management areas.
The plant was reactivated from 1965 through 1973 for the production of bombs, projectiles, and
microgravel mini-mines used in the Vietnam conflict. Mason & Hanger was retained as the operator during this
period of operation (USATHAMA, 1980). In 1973, operations ceased; the plant was again placed an standby
and has not been reactivated to date. The State Game Commission gave thirty acres of the Sand Pit Area to
the State of Nebraska in 1977 for use. Activities at CHAAP are currently limited to maintenance operations,
leasing of property for agriculture, leasing of buildings for storage and industrial operations, and wildlife
management. Site-specific operational history at the four sites designated as OU3 is discussed in Sections
6, 7, 8, and 9.
3.2

ENFORCEMENT ACTIVITIES

A Federal Facility Agreement (FFA) was signed between the U.S. Army, USEPA, and the State of
Nebraska (effective September 4, 1990) to set terms for the Remedial Investigation/Feasibility Study (RI/FS)
effort. The FFA provided the terms, listed documents to be generated, and established target dates for delivery
of reports. This ROD is being conducted in accordance with the terms outlined in the FFA.
3.3

ENVIRONMENTAL INVESTIGATIONS AND REMEDIAL ACTIONS

Several environmental studies have been conducted at CHAAP and in the surrounding area to assess
and delineate contamination. Provided below are the major environmental investigations and remedial actions
that led to the development and selection of preferred remedial alternatives for the AOCs designated as OU3.
3.3.1

Environmental Studies at CHAAP

The following sections summarize environmental investigations and studies conducted at CHAAP since
1980 that determined the nature and extent of contamination at AOCs designated as OU3.
Installation Assessment of CHAAP, March 1980
As a part of the U.S. Army’s Installation Restoration Program, U.S. Army Toxic and Hazardous
Materials Agency (USATHAMA) conducted an installation assessment of the CHAAP. The objective of this
study was to assess the environmental quality of CHAAP with regard to the use, storage, treatment, and
disposal of toxic and hazardous materials, and to define any conditions that may adversely affect health and
welfare, or result in environmental degradation.
Environmental Photographic Interpretation, March 1982 and September 1991
USEPA, the Army, and the Environmental Photographic Interpretation Center (EPIC) provided imagery
analysis for the USATHAMA Installation Assessment Project. The task included a detailed historical analysis
of the CHAAP to identify possible areas of past use, storage, treatment and disposal of potentially hazardous
materials.
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A more comprehensive analysis of aerial photographs was issued by EPIC in September 1991 and
includes historical photographs dating from 1938 to 1991. Similar to the 1982 EPIC Report, the 1991 report
included a detailed historical analysis of CHAAP to identify possible areas of past use, storage, treatment, and
disposal of potentially toxic and hazardous materials.
The studies noted trenched areas, liquids, ground scars, ground staining, and drainage passing through
potentially contaminated areas at the Sanitary Landfill. In the Shop Area, drainage ditches passing through
ground-stained loading areas were noted. Within the Nitrate Area, abundant ground staining and open storage,
including possible drummed materials, were evident.
Preliminary Contamination Survey, August 1982
Mason & Hanger contracted Envirodyne Engineers, Inc. (EEI) to conduct a preliminary contamination
survey of CHAAP. As a part of this survey, 33 groundwater monitoring wells were installed to assess the water
table configuration, estimate groundwater flow velocities, and serve as a groundwater sampling network. These
wells were installed around the Nitrate Area and Burning Grounds.
Excessing Assessment 1991
From 1989 through 1991, USATHAMA conducted an Excessing Assessment (EA) to determine the
existence of or potential for environmental contamination and to assess human health and environmental risks
associated with excessing the installation.
All of the AOCs designated as OU3 with respect to potential environmental contamination were
investigated. The 1991 EA field investigation included:
•

Geophysical surveys at the Sanitary Landfill and the Pistol Range;

•

Installation of new monitoring wells at the Sanitary Landfill;

•

Groundwater sampling using new and existing monitoring wells;

•

Surface soil sampling at the Sanitary Landfill and Pistol Range; and

•

Soil borings at the Sanitary Landfill and Pistol Range.

The results of the 1991 EA were subsequently used to supplement the 1996 RI.
Site Characterization Document (SCD) 1993
The task was initiated by the U.S. Army Environmental Center (USAEC) as a RI/FS to gather
information sufficient to support an informed risk management decision and defining the nature and extent of
contamination. Following review of the Draft RI by USEPA Region VII and NDEQ, data gaps and concerns were
identified which required significant additional site investigation in order to fully characterize the nature and
extent of contamination and complete a RI. Due to the significance of data gaps, the risk assessment was
removed from the document and the RI was reissued as a SCD.
The study areas investigated included previously identified on-post AOCs and the area east of CHAAP
that has been impacted by contaminants from the facility. The field program included sampling and analysis
of soil, groundwater, and surface water. As agreed upon by USEPA and NDEQ, the results of the 1993 SCD
have been used where applicable to support the preparation of the 1996 Rl.
Remedial Investigation 1996
The 1996 RI addressed 1994 SCD data gaps identified by USEPA and NDEQ. A streamlined risk
assessment was also prepared. Previous data collected as a part of the 1991 EA, 1994 SCD, 1994 OU1
sampling effort, and the 1994 U.S. Army Corps of Engineers (USACE) Soil Removal Action were used along
with data collected in 1995 to determine the nature and extent of contamination, and determine the potential
impact to human health and the environment and building surfaces.

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3.3.2

Remedial Actions at CHAAP

Interim Soil Removal Action 1994
A USACE interim soil removal action (IRA) was performed in November-December 1994 at 25 sites at
CHAAP. Based on 1993 SCD data, USAEC identified 25 sites, including the Sanitary Landfill (IRA Site No. 2).
USACE performed this removal action in November and December of 1994, removing approximately 5,000 tons
of explosives-contaminated soils based on action levels of 5 µg/g for 246-TNT and or RDX in soils.
Approximately one foot of contaminated soil was removed from each of IRA Sites 1-24. At IRA site 25, soil
removal was conducted to a depth of 11 ft. At the Sanitary Landfill (IRA Site No. 2), approximately 20 tons (13.4
cy) of soil were removed.
Following the initial excavation of the 25 areas in November 1994, screening level colorimetric and
immunoassay soil samples were collected from each excavation to assess the concentrations of 246-TNT and/or
RDX in soils. Based on these screening results, 15 of the excavations (excluding the Sanitary Landfill) were
identified as requiring additional excavation to meet the previously established (i.e., 1987-1988 incineration
project) action levels.
Following excavation, waste classification sampling of the removed soils was conducted and all soil
was removed offsite to the Highway 36 Land Development Company located near Deer Trail, Colorado. With
the exception of IRA Site 25, the excavations were not backfilled to allow for 1995 RI confirmation sampling.
3.4

HIGHLIGHTS OF COMMUNITY PARTICIPATION

The Proposed Plan for OU3 was released to the public on April 21, 1999, at the information repositories
listed below:
•

CHAAP, 102 North 60th Street, Grand Island, NE 68802

•

Grand Island Public Library, 211 North Washington Street, Grand Island, NE 68802 Phone: (308)
381-5333

The notice of availability of these documents was published on April 19, 1999, in the Grand Island
Independent. A public comment period was held from April 21, 1999 through May 21, 1999. A public meeting
was held at the community room of Grand Island City Hall on April 28, 1999, to inform the public about the
preferred remedial alternative for the Nitrate Area and to seek public comments. At this meeting, representatives
from the U.S. Army, USEPA, and NDEQ were present to answer questions about the site and remedial
alternatives under consideration.

 4.0

SUMMARY OF SITE RISKS

4.1

HUMAN HEALTH RISKS

A human health risk assessment (HHRA) was performed during the 1996 RI to evaluate the potential
human health effects associated with chemical contamination from past operations at CHAAP. COPCs were
identified for each site evaluated in the RI. However, risks associated with soil exposure to humans were
evaluated at areas assumed to be the three most contaminated areas at CHAAP (i.e., Burning Grounds, Pistol
Range, and Load Line 1).
Only the Pistol Range was quantitatively evaluated in the risk assessment. Groundwater, however, was
evaluated on a site-wide basis. Even though not all sites were quantitatively evaluated, COPCs were selected
for all AOCs. Provided below is a summary of the selection process.
The first step of the COPC selection process was to summarize analytical data, which were analyzed
according to USEPA’s Contract Laboratory Program (CLP) procedures. The following steps, which are in
accordance with USEPA (1989) guidance, were used to summarize the analytical data of the HHRA:
•

Data from the four sampling phases (the 1991 EA, the 1993 SCD, the 1994 OU1 Sampling Effort,
and the 1995 RI) were summarized by environmental medium (i.e., surface soil, subsurface soil,
sediment, surface water, and groundwater). In some cases, data were further grouped within an
environmental medium by location (e.g., surface soil data were grouped by source area). Because
many of the monitoring wells were sampled one or more times, only the most recent round of
chemical data from each re-sampled well was included in the HHRA.

•

Sampling data collected during the 1995 RI was compared to blank (laboratory, field, and trip)
concentration data. If the detected concentration in a site-related sample was less than 10 times
(for common laboratory contaminants), or five times (for all other compounds) the concentration
in the corresponding blank sample, the sample was qualified with a B and was treated as a
non-detect in the HHRA.

•

Data that were rejected by the laboratory were not used in the HHRA.

•

Certain analytes appeared on the target analyte list of more than one analytical method. In those
cases, data from the method specified by the CHAAP USAEC Quality Assurance Project Plan
were used in the HHRA.

•

Data from duplicate samples (samples collected from the same sample location at the same time)
were averaged together and treated as one result. If a chemical was detected in only one of the
two duplicate samples, the detected value was averaged with one-half the quantitation limit of the
non-detect sample, and the result was counted as one detect sample.

•

Mean chemical concentrations for a given medium were calculated by averaging the detected
concentrations with one-half the sample quantitation limit of the non-detects. One-half the sample
quantitation limit is typically used in the HHRA when averaging non-detect concentrations because
the actual value can be between zero and a value just below the sample quantitation limit.

•

Due to the fact that there are varying chemical- and sample-specific quantitation limits, even within
one medium, the sample quantitation limit for each non-detected sample was compared to the
maximum detected concentration for that chemical within the same grouping to determine if the
sample quantitation limit would be included in calculating the mean concentration (see previous
bullet). If the sample quantitation limit for a non-detect was two or more times higher than the
maximum detected concentration, then that sample result was not included in the calculation of
the mean for that chemical. This procedure was performed to prevent the mean from
being artificially influenced by the high sample quantification limits. As a result of this
procedure, several high sample quantitation limits were identified in the data sets
and were excluded from the calculation of mean concentrations. It should be noted

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that treatment of high non-detects in the HHRA (i.e., that non-detects that are greater than two
times the detection limit are eliminated from the data set) differs slightly from the methodology
presented in USEPA (1989), where it is stated the high non-detect should be excluded from the
data set if it causes the exposure concentration to exceed the maximum detected concentration
for the particular sample set. The uncertainty associated with this procedure is discussed in the
Uncertainty Section.
•

Frequency and detection was calculated as the number of samples in which the chemical was
detected over the total number of samples collected for the particular grouping. The frequency and
detection was determined after averaging duplicate samples collected from the same sample
location.

Based on the review of the summarized data, chemicals were selected for further evaluation using the
following methodology:

4.1.1

•

In accordance with discussions between USEPA Region VII, NDEQ, and USAEC, a
concentration-toxicity screening was conducted for all non-carcinogenic chemicals in each
sampled medium (all detected carcinogenic chemicals were retained for evaluation, in accordance
with USEPA Region VII protocols). The maximum concentration of each noncarcinogenic chemical
detected in a medium was multiplied by the inverse of its respective non-carcinogenic toxicity
criterion to determine a concentration toxicity ratio for the particular chemical. Once all
concentration-toxicity ratios were calculated, they were summed, and each individual ration was
divided by the sum of all ratios. The chemicals that accounted for greater than 0.1% of the relative
site-wide risk were then selected as COPCs. If an inorganic accounted for more than 0.1% of the
risk, but was within background levels (as determined in the comparison outlined in the following
bullet), it was not selected as a COPC. The concentration toxicity screening for each medium is
presented in the 1996 RI (Appendix A).

•

Standard statistical procedures were used to compare site data with site-specific background data.
These procedures included the parametric one-way Analysis of Variance (parametric ANOVA) or
the non-parametric one-way Wilcoxon rank-sum test. The parametric ANOVA is generally
considered the preferred test for these comparisons, but the use of the parametric ANOVA requires
that the data fit a normal or log normal distribution and that the groups to be compared have equal
variances. In addition, the parametric ANOVA test does not perform well if a moderate number of
observations in a data set are non-detects, and USEPA recommends that the parametric ANOVA
should not be used if greater than 15% of the observations are non-detects.

Soil COPCs

COPCs for the specific sites under OU3 are presented in Tables 4-1 and 4-2 for surface and
subsurface soils.
Table 4-1. COPCs in Surface Soil for Human Receptors at the CHAAP OU3 Areas
Nitrate Area
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
Bis(2-Ethylhexyl)phthalate
Indeno(1,2,3-cd)pyrene
lsophorone
n-NitrosodiphenyIamine
PCB 1260
Chromium
Lead
Mercury
Silver
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Pistol Range
RDX
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
lndeno(1,2,3-c,d)pyrene
Arsenic
Beryllium
Lead
Mercury
Silver

Sanitary Landfill
2-Amino-4,6-dinitrotoluene
4-Amino-2,6-dinitrotoluene
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Nitrobenzene
RDX
2,4,6-Trinitrotoluene
Aluminum
Arsenic
Copper
Iron
Lead
Mercury
Silver
Vanadium
4-2

Shop Area
1,3,5-Trinitrobenzene
2,4,6-Trinitrotoluene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Alpha-Chlordane
Gamma-Chlordane
DDT
bls(2-Ethylhexyl)phthalate
lndeno(1,2,3-c,d)pyrene
lsophorone
PCB 1254
PCB 1260
Cadmium

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Table 4-1. COPCs in Surface Soil for Human Receptors at the CHAAP OU3 Areas
Nitrate Area

Pistol Range

Sanitary Landfill

Shop Area
Chromium
Lead
Mercury
Silver

Table 4-2. COPCs in Sub-surface Soil for Human Receptors at the CHAAP OU3 Areas
Nitrate Area

Pistol Range

Bis(2-Ethylhexyl)phthalate
Aluminum
Barium
Chromium
Copper
Iron
Manganese
Vanadium

4.1.2

1,3-Dinitrobenzene
RDX
Benzo(a)antracene
Benzo(a)pyrene
Benzo(b)antracene
Benzo(k)antracene
Chrysene
Dibenz(a,h)anthracene
bis(2-Ethylhexyl)phthalate
Hexachlorobenzene
Indeno(1,2,3-cd)pyrene
Aluminum
Arsenic
Barium
Chromium
Copper
Iron
Manganese
Silver
Vanadium

Sanitary Landfill
2-Amino-4,6-dinitrotoluene
RDX
2,4,6-Trinitrotolene
Benzo(a)pyrene
Benzo(b)fluoranthene
Bis(2-Ethylhexyl)phthalate
Indeno(1,2,3-c,d)pyrene
Aluminum
Barium
Chromium
Copper
Iron
Manganese
Vanadium

Shop Area
1,3,5-Trinitrobenzene
Benzo(a)pyrene
Benzo(b)fluoranthene
alpha-Chlordane
gamma-Chlordane
DDT
Heptachlor
Indeno(1,2,3-c,d)pyrene
Aluminum
Barium
Chromium
Copper
Iron
Manganese
Vanadium

Groundwater
Table 4-3 presents COPCs in groundwater at OU3.
Table 4-3. Chemicals of Potential Concern in Groundwater at CHAAP
3,5-Dinitroaniline
2-Amino-4,6-dinitrotoluene
4-Amino-2,6-dinitrotoluene
2,4-Dinitrotoluene
2,6-Ditrotoluene
RDX
1,3,5-Trinitrobenzene
2,4,6-Trinitrotoluene
Acrylonitrile
Benzene
Benzo(a)anthracene
Chrysene
1,2-Dichloroethane
bis(2-Ethylhexyl)phthalate
lndeno(1,2,3-c,d)pyrene
Methylene chloride
1,1,2-Trichloroethane
Trichloroethylene
1,2,3-Trichloropropane
1,1,2-Trifluoro-1,2-dichloroethane
Antimony
Beryllium

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Summary of Site Risks

Quantitative risk calculations for soil contaminants were not made for all AOCs at CHAAP. The Pistol
Range is the only AOC designated as OU3 for which a risk assessment was quantitatively performed. Table
4-4 presents the exposure pathways evaluated in the HHRA.
Table 4-4. Exposure Pathways Evaluated in the HHRA
Environmental Media
Surface Soil

Subsurface Soil

Current Land Use

Future Land Use

Incidental ingestion by trespasser.

Incidental ingestion by trespasser.

Dermal contact of chemicals by trespasser.

Dermal contact of chemicals by Agricultural
Resident.

N/A

Incidental ingestion by excavation worker.
Dermal contact of chemicals ingestion by
excavation worker.
Inhalation of airborne particulate matter by
excavation worker.

Groundwater

Ingestion of groundwater of on-post
groundwater from an irrigation well by farmer.

Ingestion of groundwater by an agricultural
resident.

Ingestion of off-post groundwater by a
resident.

Inhalation of VOCs in groundwater by an
agricultural resident wile showering.

Dermal absorption of chemicals in off-post
groundwater by a resident while bathing.

Dermal absorption of chemcials in
groundwater by an agricultural resident while
bathing.

Ingestion of crops that have been irrigated
with off-post groundwater by a resident.

Ingestion of crops that have been irrigated
with groundwater.

Provided below is the summary of risks for the Pistol Range, the only OU3 AOC quantitatively evaluated
in the HHRA.
Surface Soil: Excess lifetime cancer risks associated with exposures to surface soil (i.e., incidental
ingestion and dermal absorption) by trespassers under current land-use conditions at the Pistol Range were
below the 1x10-6 risk level. The hazard index (HI) was less than one for these pathways, indicating that adverse
non-carcinogenic effects would not likely to occur to trespassers. Excess lifetime cancer risks for agricultural
child and adult residents under future land-use conditions due to contact with surface soil were above 1 x10-6;
however, they were equal to or below 1 x10-5. HIs were less than one, indicating that non-carcinogenic effects
would not likely occur.
Subsurface Soil: Excess lifetime cancer risks associated with exposures to subsurface soil (i.e.,
incidental ingestion, dermal absorption, and inhalation) by excavation workers under future land-use conditions
at the Pistol Range were equal to or below the 1 x10-6 risk level. The HI was less than one for these pathways,
indicating that adverse non-carcinogenic effects would not likely to occur to excavation workers.
Lead: For the evaluation of lead, the Integrated Exposure Uptake/Biokinetic (IEUBK) model was used.
The IEUBK model combines measured site lead concentrations in soil and groundwater with model intake
parameters for each background source of lead exposure (i.e., food) to provide a total estimate of lead
exposure. Risk is characterized by the probability of exceeding the blood lead level of concern (10 µg/dL).
Hypothetical exposures in young children ingesting soil from three sites (i.e., Pistol Range, Load Line 1, and
the Burning Grounds) was the exposure scenario used for running the model. Results of the model predicted
that the soil lead concentrations (arithmetic mean surface soil exposure point concentration of 5,900 µg/g) at
the Pistol Range are likely to have an adverse effect on the exposed child resident.
Groundwater: Groundwater was evaluated on a site-wide basis. The results of the HHRA indicated that
for groundwater, only the explosives plume (addressed in the OU1 interim ROD) was associated with an excess
lifetime cancer risk above the 1x10-4 risk level for future agricultural residents drinking and dermally absorbing
COPCs in groundwater. Noncarcinogenic adverse effects associated with COPCs in groundwater (OU1 only)
could be possible for future agricultural residents if groundwater ingestion and dermal exposure to COPCs were
to occur under the conditions assumed in the HHRA.
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4.2

ECOLOGICAL RISK

An ecological risk assessment (ERA) was performed to assess the potential for adverse effects to
ecological receptors resulting from exposure to site-related chemicals detected in surface soil, surface water,
and sediment at CHAAP. The receptor species and/or groups that were selected for quantitative evaluation at
CHAAP include terrestrial plants, earthworms, aquatic life, deer mouse, deer, and the American robin.
4.2.1

Nitrate Area

Results of the ERA indicate that exposures that derive from constituent concentrations in soil exceed
Toxicity Reference Values (TRVs) (i.e., guidelines that represent levels that are protective to receptors).
Therefore, there is potential for adverse effects to occur to individual plants from chromium, lead, and zinc.
Adverse effects to individual plants from exposure to lead and zinc are possible; however, adverse effects to
populations are unlikely given the concentrations detected. However, population effects are possible from
exposures to chromium. Chromium was the only COPC that has the potential to cause adverse effects to
individual earthworms. Risks to other groups/receptors are minimal at the Nitrate Area.
Risks associated with exposures to chemicals in surface soil at the Nitrate Area should be considered
an overestimation because the Nitrate Area is generally considered to have poor quality habitat due to past and
present uses (i.e., industrial operations) and/or abundance of manmade structures. As a result of the poor
quality habitat, extensive use of these areas by terrestrial receptors is unlikely, and therefore, ecological risk
is not a driver for remedial action.
4.2.2

Pistol Range

Results of the ERA indicate that exposures that derive from constituent concentrations in soil exceed
TRVs. There is a limited potential for adverse effects to individual plants and earthworms from lead at the Pistol
Range.
Risks associated with exposures to chemicals in surface soil at Pistol Range, particularly the shooting
range berm, should be considered an overestimation. This statement is supported by the fact that terrestrial
receptors would more likely occur in areas adjacent to the Pistol Range, such as cropland or shelterbelt areas,
where the habitat quality is better, food is more plentiful, and chemical contamination may be minimal or
nonexistent. Due to these reasons, ecological risk is not a driver for remedial action.
4.2.3

Sanitary Landfill

Results of the ERA indicate that exposures that derive from constituent concentrations in soil exceed
TRVs. Therefore, there is potential for adverse effects to occur to individual plants and earthworms from these
compounds. Risks to other groups/receptors are minimal at the Sanitary Landfill.
Risks associated with exposures to chemicals in surface soil at the Sanitary Landfill should be
considered an overestimation because the Sanitary Landfill is generally considered to have poor quality habitat
due to past and present uses (i.e., industrial operations). As a result of the poor quality habitat, extensive use
of these areas by terrestrial receptors is not expected.
4.2.4

Shop Area

Results of the ERA indicate that exposures that derive from constituent concentrations in soil exceed
TRVs. Risks to other groups/receptors are minimal at the Shop Area.
Risks associated with exposures to chemicals in surface soil at the Shop Area should be considered
an overestimation because the Shop Area is generally considered to have poor quality habitat due to past and
present uses (i.e., industrial operations) and/or abundance of manmade structures. As a result of the poor
quality habitat, extensive use of these areas by terrestrial receptors is not expected.

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 5.0
5.1

REMEDIAL ACTION OBJECTIVES
REMEDIAL ACTION OBJECTIVES FOR SOIL

Results of the HHRA indicate that potential risks associated with exposure to chemicals at CHAAP
were within acceptable range for carcinogens and below the HI trigger value of 1.0 for noncarcinogens for the
worst contaminated site in OU3 (i.e., Pistol Range). However, from a comparative analysis, the Army indicated
that risks associated with other, less contaminated sites should be lower than those at the Pistol Range.
Because a risk assessment was not performed for each site, the Army, EPA and NDEQ agreed to develop
cleanup levels using industrial exposure scenarios combined with a health-protective target risk of 10-6 for
carcinogens and a HI of one for noncarcinogens. When completed, remedial activities achieving these
risk-based cleanup objectives (Remedial Action Objectives [RAOs]) will ensure the protection of both
agricultural and industrial workers. It should be noted that for lead and polycyclic hydrocarbons, numerical
standards provided by NDEQ were used to achieve RAOs.
For lead, the results of the IEUBK model show that adverse effects are possible from exposure of lead
to children (incidental ingestion). The potential adverse effect triggered the need for RAOs for lead. The NDEQ,
To-Be-Considered (TBC) guidance of 400 mg/kg is considered to be protective of human health under
non-residential conditions.
Polycyclic aromatic hydrocarbons (PAHs) were also identified as soil COPCs at several AOCs at OU3.
The risk-based cleanup levels calculated were far below the numerical cleanup level typical of sites in Nebraska.
With concurrence from USEPA, the NDEQ guidance of 33 mg/kg is considered protective of non-residential
use.
5.1.1

Methodology for Calculating COPC Cleanup Levels

Because the HHRA did not quantitatively evaluate each site, the Army proposed RAOs that would be
protective of residents/workers involved with agricultural, light industrial, and other non-residential activities.
Cleanup levels for COPCs were calculated using industrial exposure values and a conservative 1x10-6 target
excess individual lifetime cancer risk. Cleanup levels for noncarcinogens were based on a target hazard quotient
of 1.
The equation used to calculate worker cleanup levels for chemicals exhibiting carcinogenic

Cs =

TR * BW * ATc * DAYS
1
*
IR * EF * ED * CF
CSFO

effects is as follows:
where:
Cs
TR
BW
ATc
DAYS
IR
EF
ED
CF
SFo

=
=
=
=
=
=
=
=
=
=

chemical concentration in soil (mg/kg),
target excess individual lifetime cancer risk (1 x10-6),
body weight (70 kg),
averaging time for carcinogenic effects (70 years),
conversion factor (365 days/year),
soil ingestion rate (50 mg/day),
exposure frequency (250 days/year),
exposure duration (25 years),
conversion factor (kg/10-6 mg), and
oral cancer slope factor ([mg/kg-day]-1).

The equation used to calculate worker cleanup levels for chemicals exhibiting non-carcinogenic effects is:

Cs =
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THQ * BW * ATnc * DAYS
1
*
IR * EF * ED * CF
CSFO
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 Section 5.0
Remedial Action Objectives

where:
Cs
THQ
BW
Atnc
DAYS
IR
EF
ED
CF
RfDo

=
=
=
=
=
=
=
=
=
=

chemical concentration in soil (mg/kg),
target hazard quotient (1),
body weight (70 kg),
averaging time for non-carcinogenic effects (25 years),
conversion factor (365 days/year),
soil ingestion rate (50 mg/day),
exposure frequency (250 days/year),
exposure duration (25 years),
conversion factor (kg/10-6 mg), and
oral reference dose (mg/kg-day).

The toxicity criteria (i.e., cancer slope factors and non-cancer reference doses) were obtained from the
Integrated Risk Information System (IRIS) or Health Effects Assessment Summary Tables (HEAST). Exposure
parameters for workers that were obtained from USEPA (1991) included the body weight, averaging time, soil
ingestion rate, exposure frequency, and exposure duration.
Tables 5-1 through 5-4 present cleanup levels for COPCs at OU3 AOCs.
Table 5-1. Cleanup Levels for Soil COPCs (µg/g) at the Nitrate Area
Chemical
Calculated Industrial Risk-Based (µg/g)*
Aluminum
1,000,000
Barium
143,080
Benzo(a)anthracene
331
Benzo(a)pyrene
331
Benzo(b)fluoranthene
331
Benzo(k)fluoranthene
331
Bis (2-ethylhexyl)phthalate
409
Chromium
10,220
Chrysene
784
Copper
75,628
Dibenz(a,h)anthracene
331
lndeno(1,2,3-c,d)pyrene
33
Iron
613,200
lsophorone
6,024
Lead
4002
Manganese
49,056
Mercury
613
n-Nitrosodiphenylamine
1,022
PCB 1260
3
Silver
10,220
Vanadium
14,308
* - For carcinogens, concentrations are associated with a risk of 1 x 10-6
1
- Cleanup level for PAHs is NDEQ TBC Guidance
2
- Cleanup level for lead is NDEQ TBC Guidance
Table 5-2. Cleanup Levels for Soil COPCs (µg/g) at the Pistol Range
Chemical
Calculated Industrial Risk-Based levels (µg/g)*
Aluminum
1,000,000
Arsenic
See Section 5.3
Barium
143,080
Beryllium
See Section 5.3
Benzo(a)anthracene
331
Benzo(a)pyrene
331
Benzo(b)fluoranthene
331
Benzo(k)fluoranthene
331
Bis(2-ethylhexyl)phthalate
409
Chromium
10,220
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 Section 5.0
Remedial Action Objectives

Table 5-2. Cleanup Levels for Soil COPCs (µg/g) at the Pistol Range
Chemical

Calculated Industrial Risk-Based Levels (µg/g)*

Chrysene
Copper
Dibenz(a,h)anthracene
1,3-Dinitrobenzene
Hexachlorobenzene
Indeno(1,2,3-c,d)pyrene
Iron
Lead
Manganese
Mercury
RDX
Silver
Vanadium

784
75,628
331
204
4
33
613,200
4002
49,056
613
52
10,220
14,308

* - For carcinogens, concentrations are associated with a risk of 1 x 10-6
1
- Cleanup level for PAHs is NDEQ TBC Guidance
2
- Cleanup level for lead is NDEQ TBC Guidance

Table 5-3. Cleanup Levels for Soil COPCs (µg/g) at the Sanitary Landfill
Chemical
Aluminum
2-Amino-4,6-dinitrotoluene
4-Amino-2,6-dinitrotoluene
Arsenic
Barium
Benzo(k)pyrene
Benzo(b)flouranthene
Bis (2-ethylhexyl)phthlalate
Chromium
Copper
2,4-Dinitrotoluene
2-6-Dinitrotoluene
Indeno(1,2,3-c,d)pyrene)
Iron
Lead
Manganese
Mercury
Nitrobenzene
RDX
Silver
2,4,6-Trinitrotoluene
Vanadium

Calculated Industrial Risk-Based (µg/g)*
1,000,000
123
123
See Section 5.3
143,080
331
331
409
10,220
75,628
8.42
8.42
33
613,200
4002
49,056
613
1,022
520
10,220
191
14,308

* - For carcinogens, concentrations are associated with a risk of 1x10-6
1
- Cleanup level for PAHs is NDEQ TBC Guidance
2
- Cleanup level for lead is NDEQ TBC Guidance
Table 5-4. Cleanup Levels for Soil COPCs (µg/g) at the Shop Area
Chemical

Calculated Industrial Risk-Based Levels (µg/g(*

Aluminum
Barium
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Bis(2-ethylhexyl)phthalate
Cadmium
alpha-Chlordane

1,000,000
143,080
331
331
331
331
409
2,044
4.4

gamma-Chlordane

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Record of Decision for Remedial Action (OU3)
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 Section 5.0
Remedial Action Objectives
Table 5-4. Cleanup Levels for Soil COPCs (µg/g) at the Shop Area
Chemical

Calculated Industrial Risk-Based Levels (µg/g(*

Chromium

10,220

Copper

75,628

DDT

17

Heptachlor

1

Indeno(1,2,3-c,d)pyrene

33

Iron

613,200

Isophorone

6,024

Lead

4002

Manganese

49,056

Mercury

613

PCB 1254
PCB 1260

3
3

Silver

10,220

1,3,5-Trinitrobenzene

102

2,4,6-Trinitrotoluene

191

Vandium

14,308
* - For carcinogens, concentrations are associated with a risk of 1x10-6
1 - Cleanup level for PAHs is NDEQ TBC Guidance
2 - Cleanup Level for Lead is NDEQ TBC Guidance

5.2

REMEDIAL ACTION OBJECTIVES FOR GROUNDWATER

The RAO for groundwater was to achieve standards required for the groundwater classification at
CHAAP. The groundwater at CHAAP has been classified by the state as GA, which is for public drinking water
supply. Also, groundwater at CHAAP is considered Class 1, representing a current source of drinking water
of varying value (USATHAMA, 1992). Maximum Contaminant Levels (MCLs), which are the National Primary
Drinking Water Standards (40 CFR Part 141), are considered to be chemical-specific applicable or relevant and
appropriate requirements (ARARs) for groundwater at CHAAP. If there were no MCLs available for COPCs for
groundwater at CHAAP, cleanup levels were calculated based on risk from exposure to industrial workers.
Furthermore, the State of Nebraska has established numeric water quality standards for groundwater under the
Nebraska Administrative Code, Title 118, Groundwater Quality Standards and Use Classification, revised
effective September 3, 1991.
5.2.1

Groundwater Cleanup Levels

If COPCs did not have an applicable MCL, risk-based groundwater cleanup levels were calculated. The
equation used to calculate worker groundwater cleanup levels for chemicals exhibiting carcinogenic effects is
as follows:

C gw =

TR * BW * ATc * DAYS * CF
1
*
IR * ED * CF
CSFO

where:
Cgw
TR
BW
ATc
DAYS
CF
IR
EF
ED
SFo

=
=
=
=
=
=
=
=
=
=

chemical concentration in groundwater (pg/L),
target excess individual lifetime cancer risk (1x10-6),
body weight (70 kg),
averaging time for carcinogenic effects (70 years),
conversion factor (365 days/year),
conversion factor (103 µg/mg),
groundwater ingestion rate (1 L/day),
exposure frequency (250 days/year),
exposure duration (25 years), and
oral cancer slope factor ([mg/kg-day]-1).

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 Section 5.0
Remedial Action Objectives

The equation used to calculate worker groundwater cleanup levels for chemicals exhibiting non-carcinogenic
effects is:

Cs =

THQ * BW * ATnc * DAYS *CF
* RfDo
IR * EF * ED

where:
Cgw
THQ
BW
ATnc
DAYS
CF
IR
EF
ED
RfDo

=
=
=
=
=
=
=
=
=
=

Chemical concentration in groundwater (µg/L),
target hazard quotient (1),
body weight (70 kg),
averaging time for non-carcinogenic effects (25 years),
conversion factor (365 days/year),
conversion factor (103 µg/mg),
groundwater ingestion rate (1 L/day),
exposure frequency (250 days/year),
exposure duration (25 years), and
oral reference dose (mg/kg-day).

The target risk and hazard quotient was assumed to be a level of 1x10-6 for carcinogens and a level of
1.0 for non-carcinogens. The toxicity criteria (i.e., cancer slope factors and non-cancer reference doses) were
obtained from IRIS or HEAST. Exposure parameters for workers that were obtained from USEPA (1991)
included the body weight, averaging time, water ingestion rate, exposure frequency, and exposure duration.
Table 5-5 presents Cleanup Levels for Groundwater COPCs at CHAAP.
Table 5-5 Cleanup Levels for Groundwater COPCs (µg/L) at CHAAP
Chemical

Federal Maximum
Containment Levels (µg/L)

Calculated Industrial
Risk-Based Levels (µg/L)

Nebraska Groundwater
Standards (µg/L)

2-Amino-4,6-Dinitrotoluene

--

6.1

--

4-Amino-2,6-Dinitrotoluene

--

6.1

--

Antimony a

6

--

--

Acrylonitrile

--

0.53

--

Benz[a]anthracene

0.1

--

--

Benzene

5

--

5

Beryllium

4

--

--

Chrysene

0.2

--

--

2,4-Dinitrotoluene

--

0.42

--

2,6-Dinitrotoluene

--

0.42

--

1,2-Dichloroethane

5

--

5

Bis (2-Ethylhexyl) phthalate

b--

6

--

--

HMX

--

5,110

--

Indeno (1,2,3-c,d)pyrene

0.4

--

--

38

--

b

Methyl chloride
(dichloromethane)

5

Nitrobenzene

--

51

--

2-Nitrotoluene

--

1,022

--

3-Nitrotoluene

--

1,022

--

4-Nitrotoluene

--

1,022

--

RDX

--

2.6

--

1,3,5-Trinitrobenzene

--

5.1

--

2,4,6-Trinitrotoluene

--

9.5

--

1,1,2-Trichloroethane

5

--

--

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Final Document

 Section 5.0
Remedial Action Objectives
Table 5-5 Cleanup Levels for Groundwater COPCs (µg/L) at CHAAP
Chemical

Federal Maximum
Containment Levels (µg/L)

Calculated Industrial
Risk-Based Levels (µg/L)

Nebraska Groundwater
Standards (µg/L)

Trichloroethene

5

--

5

1,2,3-Trichloropropane

--

0.041

--

Tetryl

--

1,022

--

10

--

1,3-Dinitribenzene
--- = Standard not developed for this chemical.
a
See Section 5.3.
b
Common laboratory contaminants.

5.3

NATURALLY OCCURRING COPCS

5.3.1

Soil

Two constituents selected as soil COPCs in the HHRA are considered naturally occurring chemicals
at CHAAP. They are arsenic and beryllium.
5.3.1.1

Arsenic

Arsenic, a naturally occurring chemical at CHAAP, was selected as a COPC at the Pistol Range. In
order to place the detected concentrations into perspective, the concentrations were compared with
facility-specific and regional (Central Nebraska) background levels (Dragun and Chiasson, 1991) for determining
whether remediation of arsenic-contaminated soil would be warranted. As shown in Table 5-6, arsenic
exceeded carcinogenic cleanup levels based on target excess cancer risk of 1x10-6.

Chemical

Arsenic

Table 5-6. Comparison of Various Concentrations of Arsenic with Risk-Based Cleanup Levels
Maximum
FacilityRegional
1 x 10-6 Risk- 1 x 10-5 Risk- 1 x 10-4 RiskConcentration Specific
Upper Limit of Based
Based
Based
Detected
Upper Limit of Background
Cleanup
Cleanup
Cleanup Level
Level
Background
Level
27.0 µg/g

4.58 µg/g

12 µg/g

3.82 µg/g

38.2 µg/g

382 µg/g

Because arsenic is found in naturally high concentrations regionally and because the maximum arsenic
concentration (i.e., 27.0 µg/g) correlates with a risk of 7.07 x 10-6, no remedial alternatives were proposed in
the FS to address arsenic concentrations in soil.
5.3.1.2

Beryllium

Beryllium, classified as a carcinogen, was detected in surface soils at concentrations greater than the
target risk level of 1X10-6 but below the target risk level of 1x10-5 under the light industrial use scenario. It should
be noted that beryllium appears to be a naturally occurring element in Nebraska soils. The upper limit of
facility-specific background exceeds concentrations that correlate with a target risk level of 1X10-6. Table 5-7
presents risks associated with exposure to maximum concentrations detected in facility-specific background,
maximum concentrations detected at the Pistol Range, and concentrations that correlate with target excess
individual lifetime cancer risk levels of 1X10-4, 1x10-5, and 1x10-6.
Table 5-7. Comparison of Beryllium Concentrations and Calculated Risk Based Cleanup Levels
Sampling Location

Concentration (µg/g)

Risk

Maximum Concentration detected at Pistol Range (Test
Trench PRST07, 2 ft bgs)

4.08

5.43 x 10-6

Upper Limit of Facility-specific background (surface
soil)

1.52

2.06 x 10-6

Calculated Risk Based Cleanup Level

1.33

1 x 10-6

Calculated Risk Based Cleanup Level

13.3

1 x 10-5

Calculated Risk Based Cleanup Level

133

1 x 10-4

Based on the maximum risk (i.e., 4.08 µg/g) which correlates with a risk of 5.43 x 10-6, no remedial
alternatives were proposed in the FS to address beryllium concentrations in soil.
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 Section 5.0
Remedial Action Objectives

5.3.2

Groundwater

5.3.2.1 Antimony
The chemical-specific ARAR for antimony is the Federal MCL of 6 µg/L. However, the facilityspecific background exceeds the Federal MCL by tenfold (62.4 µg/L). The highest concentration (72.6 µg/L) is
slightly above the facility-specific background. Based on high concentrations in background which far exceed
the Federal MCL, remedial alternatives to address antimony were not proposed in the FS.

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 6.0
6.1

NITRATE AREA
OPERATIONAL HISTORY

The Nitrate Area was constructed in 1942 as part of the original facility (USAEC, 1996). During World
War II, the area was converted for the production of nitrate crystals from nitrate liquor and was known as the
Ammonium Nitrate Plant. The crystalline nitrate was used in bomb production. In 1946, the plant was again
modified to produce ammonium nitrate fertilizer. Fertilizer production ceased in 1948 and the Nitrate Area
facilities were placed on standby status.
In 1968, Building N-2 was modified and converted to provide a mine test facility in support of operations
at Load Line 5 (Mason & Hanger, 1982). Testing operations began on May 27, 1968, and stopped sometime
before mine production ceased near the end of the Vietnam conflict.
Building N-17, the Railcar Loading Area, and adjacent open storage areas have been leased to CRS
since 1979 for railroad car rebuilding, repair, and refurbishing. Railcars are currently staged throughout CHAAP
on unused rail sidings awaiting repair or refurbishment.
Major areas of environmental concern associated with the Nitrate Area that were investigated include:
Building N-17; Railroad Loading Area; Crystallization Buildings (N-5, N-17, N-9, N-13, and N-15); Chemical
Analysis Laboratory; Sanitary Leachfield; Drum Storage Area; Marsh and Pond Areas; and Drainage Ditches.
6.2

FINDINGS OF THE REMEDIAL INVESTIGATION

The sampling program at the Nitrate Area included: surface soil and sediment sampling for the 1991
EA; surface and subsurface soil sampling, groundwater sampling, and limited surface water and sediment
sampling for the 1993 SCD; and surface and subsurface soil and groundwater sampling for the 1996 RI. Exhibit
6-1 presents sampling locations of past site investigations for soil and groundwater, respectively. Exhibit 6-2
displays the locations where COPCs were detected in soil above nonresidential cleanup levels.
6.2.1 Groundwater Sampling Results
Sampling results from the two perimeter wells (G0030 and G0032) indicated that
operations at the Nitrate Area had not impacted groundwater.
6.2.2 Soil Sampling Results
General Storage Area/Salvage Yard: The General Storage Area/Salvage Yard at the Nitrate Area
contains lead above the level considered protective of human health under non-residential conditions. The
General Storage Area is located within a fenced area which surrounds Buildings N-1 and N-3. This area was
used as a salvage yard for storing unwanted equipment, excess machinery, and other items including lead
batteries, transformers, and old fuel storage tanks (Rupp, 1991). One surface soil sample, NITRSR003,
contained lead (4,600 µg/g); however, no other COPCs were detected above the calculated non-residential
risk-based cleanup levels. Lead contamination in soil appears to be confined to the surface soil. Lead was not
detected in groundwater samples, indicating that lead has likely formed a carbonate mineral phase which is
characteristic of the behavior of lead in nonacidic environments.
6.3

DESCRIPTION OF ALTERNATIVES

Based on the findings of the 1996 RI, a FS was prepared in 1998 (USACE, 1998a) to address the lead
contamination present at the Nitrate Area. Provided below are the remedial alternatives presented in the FS.
6.3.1 Alternative One: No Action for the Nitrate Area
Description: Under this alternative, no actions will be taken to address contamination at the site. The
No Action alternative is intended to serve as a baseline with which to compare the risk reduction
effectiveness of other potential alternatives. The risks that were calculated in the HHRA are based on
the scenario presented by this alternative (i.e., no active reduction of present or future potential risks).
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Record of Decision for Remedial Action (OU3)
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Section 6.0
Nitrate Area

Overall Protection of Human Health and the Environment: The No Action alternative does not decrease
the potential risks to humans or the environment in any way, as no remedial activities will be
implemented at the site under this alternative.
Compliance with ARARs: The chemical-specific cleanup TBC guidance of 400 µg/g for lead established
by the NDEQ will not be met by this alternative. Location- and action-specific ARARs are not considered
because no remedial activities will be implemented at the site.
Long-term Effectiveness and Permanence: Over the long-term, this alternative will not be effective. No
actions are taken to provide permanent human health and environmental protection.
Reduction of Toxicity, Mobility, or Volume Through Treatment: Because there are no remedial activities
implemented at the site, there will be no reduction of toxicity, mobility, or volume through treatment.
Short-term Effectiveness: There is no short-term effectiveness associated with the No Action alternative
because no additional remedial activities will be implemented at the site.
Implementability: There are no implementability concerns associated with the No Action alternative
because no further remediation activities will be conducted at the site.
Cost: The net present worth for 30 years at 5% interest for this alternative is estimated to be $37,240,
the cost of producing the Five-Year Evaluation Report required while the site is listed on the NPL.
6.3.2 Alternative Two: Excavation, Off-Site Disposal of Lead-Contaminated Soil for the Nitrate Area,
and Deed Restriction to Prevent Residential Use
Description: Alternative Two is a source removal action. Lead-contaminated soil at the General
Storage/Salvage Yard would be excavated to levels below the NDEQ cleanup guidance (400 mg/Kg) and
transported to an off-site disposal facility. Based on site investigation sampling results, an area of 10
ft by 10 ft to a depth of one foot would be excavated. The estimated amount of soils to be excavated
based on available analytical data is 4 yd3 (6 tons). The excavated areas would be backfilled with clean
soil and graded. Implementation of this alternative prevents exposure pathways via surface to workers.
Based on existing data, the lead-contaminated soil may be hazardous under Resource Conservation and
Recovery Act (RCRA) regulations. Therefore, the soil, if determined to be RCRA-hazardous, will be
disposed at a RCRA Subtitle C Landfill that can accept waste from a CERCLA site.
This alternative also includes implementation of deed restrictions to prevent residential use. The deed
restrictions will include proprietary institutional controls restricting the future use of the property such
as easements or restrictive covenants that are legally enforceable against subsequent property owners
and instituted, depending on state law, by conveyance or contract. The U.S. Army will be responsible
for implementing and maintaining the effectiveness of the institutional controls.
Overall Protection of Human Health and the Environment: Because all lead-contamination is removed
to below the cleanup level, this alternative provides protection of human health under non-residential
conditions.
Compliance with ARARs: NDEQ TBC guidance for lead will be met by this alternative. Action-specific
and location-specific ARARs for soil excavation and disposal will be addressed in the Remedial Design
for this alternative.
Long-term Effectiveness and Permanence: Lead will be removed to below 400 mg/Kg; therefore, there
is no long-term risk associated with lead assuming conditions remain non-residential.
Reduction of Toxicity, Mobility, or Volume Through Treatment: Toxicity, mobility, and volume will be
reduced for the soil medium since the contaminated soil will be removed and disposed at an off-site
disposal facility.
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 Section 6.0
Nitrate Area

Short-term Effectiveness: There will be minimal impacts to the community during implementation of this
alternative. Fugitive dust generated during excavation will be controlled using a water spray, if necessary.
Workers involved with the waste excavation and processing activities could be exposed to risks
associated with dermal contact with contaminated soil along with some risks from breathing dust and
vapors. However, the emissions levels will be low, and workers will be protected by use of appropriate
personal protection equipment.
Implementability: Equipment and materials for implementing this alternative are readily available.
Cost: The net present worth of costs for 30 years at 5% interest for this alternative is estimated to be
$132,176, the cost of excavation of lead-contaminated soil and conducting five-year site reviews.
6.4

SUMMARY OF ANALYSIS FOR THE NITRATE AREA ALTERNATIVES

As required by CERCLA, the remedial alternatives described above were evaluated using nine criteria
specified by USEPA. This section summarizes the relative performance of each of the alternatives with respect
to the nine CERCLA evaluation criteria. Table 6-1 provides a comparative analysis of the remedial action
alternatives for the Nitrate Area.
6.4.1 Protection of Human Health and the Environment
At the Nitrate Area, lead was detected at concentrations greater than the NDEQ Cleanup Guidance.
Alternative One will not meet this criterion because no actions are taken to eliminate, reduce, or control
exposure pathways. Alternative One does not achieve the threshold criterion of protection of human health and
the environment.
Alternative Two provides protection of human health and the environment by eliminating the surface soil
exposure pathway as well as mitigating migration of lead into groundwater (sources are removed).
6.4.2 Compliance with ARARs
Compliance with ARARs is a threshold criterion that must be met by the proposed remedial action.
Alternative One does not meet the chemical-specific TBC guidance because lead levels remain in soil. There
are no location-specific or action-specific ARARs associated with Alternative One. Alternative Two, however,
meets the chemical-specific TBC guidance because lead is removed. The actions taken for Alternative Two can
be performed in compliance with the action- and location-specific ARARs as identified in Table 6-3.
Table 6-1. Comparative Analysis of Remedial Action Alternatives – Nitrate Area
NCP
Alternative 1
Alternative 2
Criteria
No Action
Excavation, Off-Site Disposal of LeadContaminated Soil, and Deed
Restrictions to Prevent Residential Use
1. OVERALL PROTECTIVENESS
Direct Contact/Soil Ingestion
No significant reduction in risk.
All contamination above levels causing
Contaminant levels remain in soil
risk will be removed.
2. COMPLIANCE WITH ARARS/TBC GUIDANCE
Chemical-Specific ARARS
There are no chemical-specific
See Alternative 1
ARARs.
Location-Specific ARARs
There are no location-specific ARARs.
Should meet all location-specific ARARs.
Action-Specific ARARs
There are no action-specific ARARs.
Should meet all action-specific ARARs
TBC Guidance
Does not meet protection of industrial
Reduces lead levels in soil below
worker cleanup levels.
cleanup levels.
3. LONG-TERM EFFECTIVENESS AND PERMANENCE
Magnitude of Residual Risk (Direct
Source has not been removed.
Risk is minimized since source is
Contact/Soil Ingestion)
Existing risk will remain.
removed.
Adequacy and Reliability of Controls
No controls over remaining
Reliability of soil removal high, since all
contamination. No reliability.
lead above remedial goals will be
removed from the site.
Need for 5-Year Review
Yes.
Yes.

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 Section 6.0
Nitrate Area
Table 6-1. Comparative Analysis of Remedial Action Alternatives – Nitrate Area
NCP
Alternative 1
Alternative 2
Criteria
No Action
Excavation, Off-Site Disposal of LeadContaminated Soil, and Deed
Restrictions to Prevent Residential Use
4. REDUCTION IN TOXICITY, MOBILITY, AND VOLUME THROUGH TREATMENT
Treatment Process Used

None.

Stabilization at off-site disposal facility
mat be required.

None.

None.

None.

No reduction in toxicity or mobility, but
volume of contaminated soil is reduced.

Irreversible Treatment

None.

None.

Type and Quantity of Residuals
Remaining after Treatment

N/A

No detectable residuals remain above
cleanup level of 400 µg/g.

Statutory Preference for Treatment

Does not satisfy.

Does not satisfy.

Community Protection

Risk to community not increased
by remedy implementation.

Temporary increase in dust production
during excavation.

Worker Protection

No significant risk to workers.

Protection required against dermal
contact and inhalation of contaminated
dust during excavation activities.

Environmental Impacts

Continued impact from existing
conditions.

No environmental impacts from remedial
action.

Time until Action is Complete

Not Applicable.

Six months.

No approval necessary.

Yes.

Availability of Services and Capacities

No services or capacities
necessary.

Services or capacities are readily
available.

Availability of Equipment, Specialists, and
Materials.

None required.

Equipment, specialists, and materials are
readily available.

Availability of Technologies.

None required.

Excavation and disposal technologies
readily available.

Capital Cost

$0

$71,381

O&M Cost

$28,000

$28,000

Present Worth Cost

$37,240

$132,176

Amount Destroyed or Treated
Reduction of Toxicity, Mobility, or

Volume

5. SHORT-TERM EFFECTIVENESS

6. IMPLEMENTABILITY
Ability to Obtain Approvals and Coordinate
with other Agencies

7. COST

6.4.3

Long-term Effectiveness and Permanence

Alternative One does not provide long-term effectiveness and permanence. This alternative does not
provide sufficient, effective protection of groundwater and potential exposure to humans from exposure to
contaminated soils. Alternative Two provides long-term prevention of exposures to contaminated surface soil
and migration of lead into groundwater because all sources are removed.
Reviews at least every five years, as required, would be necessary to evaluate the effectiveness of any
of these alternatives because hazardous substances would remain onsite in concentrations above health-based
levels.
6.4.4

Reduction of Toxicity, Mobility or Volume through Treatment

Alternative One does not provide reduction of toxicity, mobility, or volume of the contaminants.
Alternative Two provides reduction of toxicity, mobility, and volume because all lead-contaminated soils are
removed to below the cleanup level protective of human health under non-residential conditions.
6.4.5

Short-term Effectiveness

Short-term effectiveness is not applicable to Alternative One. For Alternative Two, the use of proper dust
suppressant measures will control windblown emissions of contaminated dust to protect the CRS personnel
and on-site workers. Proper personal protective equipment would be required for site workers. Measures to
protect the environment are not expected for implementing Alternative Two.
DAAA15-91-D-0014
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October 1999

6-6

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 6.0
Nitrate Area

The length of time required to implement and complete the remedial alternatives are as follows:
Alternative One is a “No Action” altemative, therefore, no time is required; Alternative Two would require six
months to implement.
6.4.6

Implementability

Alternative One, a no further action alternative, is the most easily implemented because it entails no
remedial action. However, Alternative Two is also easy to implement because it uses readily available
equipment and materials. Alternative Two involves the excavation of lead-contaminated soil and sampling. The
excavation (approximately 1 ft bgs) would not require shoring or dewatering.
6.4.7

Cost

Total capital costs, annual operation and maintenance (O&M) costs, and present worth (discount rate
of 5%) for each alternative is presented in Table 6-2. The progression of total present worth from least
expensive to most expensive alternative is Alternative One and Alternative Two. Table 6-2 provides a detailed
cost estimate for Alternative Two at the Nitrate Area.
6.5

SELECTED REMEDY

The selected remedy to address soil contamination at the Nitrate Area is Alternative – Two Excavation,
Off-Site Disposal of Lead-Contaminated Soil, and Deed Restriction to Prevent Residential Use (Exhibit 6-3).
Alternative Two is the preferred alternative because it provides the best balance of features that offer overall
protection to human health and the environment. Excavation of contaminated soils will mitigate risks to human
health. Furthermore, this action is easy to implement and involves minimal risks to site workers. The deed
restrictions will include proprietary institutional controls such as easements or restrictive covenants that are
legally enforceable against subsequent property owners and instituted, depending on state law, by conveyance
or contract. The U.S. Army will be responsible for implementing and maintaining the effectiveness of the
institutional controls. Table 6-2 presents the detailed cost estimate and Tables 6-3, 6-4 and 6-5 present
ARARs/TBC guidance applicable to the preferred alternative.
6.6

EXPLANATION OF SIGNIFICANT CHANGES

The Proposed Plan presents the selected remedy as the preferred alternative. No significant changes
have been made.

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October 1999

6-7

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 6.0
Nitrate Area
Table 6-2 Cost Estimate for Preferred Alternative for Excavation, Off-Site Disposal of
Lead-Contaminated Soil, and Deed Restriction to Prevent Residential Use
Remedial Action
Capital
Work Plan
Pre-Construction Meeting
Site Mobilization/Setup
Contaminated Soil Removal (Excavation)
Waste Characterization
Waste Disposal and Transportation
Soil Transportation (Rolloff)
IDW
Disposal Arrangements
Labor
Post Excavation Sampling
Total Lead
XRF Screening
Labor
Site Restoration
Backfilling With Clean Soil
Top Soil
Grading And Seeding
Demobilization
Closure Report
Deed Restriction

Units

No.

Report
Meeting
Site
Site
Site

1
1
1
1
1

Ton
55-Gal Drum
Site
Site

Unit Price
$17,250.00
$6,960.00
$7,000.00
$5,978.00
$2,560.00

$17,250.00
$6,960.00
$7,000.00
$5,978.00
$2,560.00

5.6
2
1
1

$265.00
$130.00
$677.00
$6,127.00

$1,484.00
$260.00
$677.00
$6,127.00

Sample
Week
Day

5
1
1

$35.00
$2,000.00
$650.00

$175.00
$2,000.00
$650.00

CY
CY
SY
Site
Report
Each

2.50
2.50
11.0
1
1
1

$15.00
$30.00
$2.00
$6,000.00
$9,125.00
$5,000.00
Subtotal Capital Cost

$37.50
$75.00
$22.00
$6,000.00
$9,125.00
$5,000.00
$71,381.00

$10,000.00

$10,000.00
$28,000.00
$28,000.00
$99,381.00
$24,845.00
$7,950.00
$132,176.00

O & M Cost
5-Year Site Review (30-Year Period)
Each
Present Worth 5-Year Site Reviews (30-Year Period @ 5%)

1

Subtotal O & M Cost
Subtotal Cost of Alternative
Contingency (@ 25%)
Project Management (@ 8%)
Total Cost Alternative

DAAA15-91-D-0014
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October 1999

Cost

6-8

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 6.0
Nitrate Area
Table 6-3. Action-Specific ARARs for Preferred Alternative for Excavation, Off-Site Disposal of
Lead-Contaminated Soil, and Deed Restriction to Prevent Residential Use
Type of Action
Excavation

Closure and PostClosure

Disposal of Soil

Regulation/Citation
Regulations to processing machines and equipment (NDEC
Title 129 Chapter 4)
Dust generation during construction activities (NDEC Title 129
Chapter 17)
Disposal or decontamination of equipment, structures, etc.
(40 CFR 264.114)
On-Site health and safety for personnel during remedial
actions (29 CFR 1910)
Clean Closure (40 CFR 264.111)
Closure with Waste in Place (40 CFR 264.228)
Post-Closure Care (40 CFR 264.117)
Hazardous Waste Determination (40 CFR 261)
Standards for generators (40 CFR 262)
Standards for transporters (40 CFR 263; NDEC Title 128 Ch 3
and Ch 17; and 49 CFR 171)
LDRS and Treatment Standards (40 CFR 268)

Applicable/Relevant/
Appropriate
Relevant
Relevant
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable

Table 6-4. Location-Specific ARARs for Preferred Alternative for Excavation, Off-Site Disposal of
Lead-Contaminated Soil, and Deed Restriction to Prevent Residential Use
Regulation/Citation
Executive Order 11988 (Floodplain Management) Evaluate potential effects of actions,
avoid impacts to the extent possible (40 CFR 6, Appendix A)
Presence of those species listed in the Endangered Species Act (16 USC 1351 et seq.),
the Fish and Wildlife Coordination Act (16 USC 661 et seq.), 40 CFR 6.302(h), 50 CFR 402,
CWA 404, and 40 CFR 231.10(b), and RSN 37-430 to -438 as being rare, threatened or
endangered.
Presence of farmlands as defined under 7 CFR 658.4 and 658.5 and the Farmland
Protection Relevant Policy Act (7 USC 4201 et seq.)

Applicable/Relevant/
Appropriate
Relevant
Relevant

Relevant

Table 6-5. Chemical-Specific ARARs for Preferred Alternative for Excavation, Off-Site Disposal of
Lead-Contaminated Soil, and Deed Restriction to Prevent Residential Use
Constituent
Lead

DAAA15-91-D-0014
TEPS14-14
October 1999

Regulation
NDEQ TBC Guidance. Protective of Human Health under nonresidential conditions.

6-9

Concentration
400 mg/Kg

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 7.0
7.1

PISTOL RANGE
OPERATIONAL HISTORY

The Pistol Range was the site of a destruction area for all the scrap and rejected explosives generated
by the Load Line 5 Aerial Mine Program. Based on review of correspondence in Mason & Hanger files, the site
appears to have been active from April 1968 until the spring of 1969. CHAAP Standard Operating Procedure
(SOP) 612 for the "Pistol Range Demolition Area" (Mason & Hanger, 1988) provides operational guidelines for
the following operations:
•

Static ejection of mines from canisters;

•

Burning of RDX and desensitized lead azide;

•

Detonation of canisters;

•

Detonation of mines;

•

Disposal of RDX-contaminated material;

•

Burning of XM45E1 mines;

•

Detonation of bulk lead azide; and

•

Disposal of explosives-contaminated freon.

Based on aerial photographs and historical documents, the following four potential AOCs were identified
in the Pistol Range Area: the Burning Pit Area; the Storage Pad; the Firing Range/Backstop Berm/Static
Election Test Site; and the Decanting Station and Leaching Pit Area. The Burning Pit Area is the AOC at the
Pistol Range that contains contamination above levels considered protective of human health under
non-residential conditions.
The Burning Pit Area, located in the northern portion of the Pistol Range study area, was used for
explosives demolition. According to a Mason & Hanger engineering drawing, burning and demolition operations
took place north of the small arms fire backstop berm in a series of eight burning pits (Test Trenches: PRST07,
PRST08, PRST09, PRST10, PSRGST002, PSRGST003, PSRGST004, and PSRGST006) that were 4 ft deep,
2-4 ft in width, and ranged from 8-40 ft in length (Mason & Hanger, 1969). Desensitized lead azide, microgravel
mini-mines, and explosives-contaminated trash were regularly dumped into burning pits, doused with fuel oil,
and ignited. Unexploded mines and bulk explosives scattered over the ground during demolition events were
soaked with liquid freon, transported back to the burning pits, and re-ignited. During the 1995 Rl field effort, this
area was a flat dry-cultivated field.
7.2

FINDINGS OF THE REMEDIAL INVESTIGATION

The sampling program at the Pistol Range was as follows: geophysical surveying and surface soil
sampling for the 1991 EA; geophysical surveying, surface and subsurface soil sampling, test trench excavating,
and groundwater sampling for the 1993 SCD; and geophysical surveying, surface and subsurface soil sampling,
test trench excavating, and groundwater sampling for the 1996 Rl. Exhibit 7-1 presents sampling locations of
previous investigations at the Pistol Range. For the sampling program at the Pistol Range, refer to investigative
program summary in the 1996 RI. Exhibit 7-2 displays the locations where COPCs were detected in soil above
the non-residential cleanup levels.
7.2.1

Soil Sampling Results

The Test Trenches and Static Ejection Site/Backstop Berm were the only areas within the Pistol Range
where contaminants exceeded cleanup levels. Provided below is a summary of COPC contamination at these
areas that triggered the need for an alternatives analysis for this AOC.
Test Trenches:
•

Test Trench PRST07 S Lead (1,700-2,900 µg/g) was detected above the NDEQ TBC Guidance of
400 mg/Kg.

DAAA15-91-D-0014
TEPS14-14
October 1999

7-1

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

  

 

  

 

 

 


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Section 7.0
Pistol Range

Explosives COPC RDX (12 µg/g at 1.5 ft bgs, 1,500 µg/g at 2 ft bgs) exceeded the calculated
non-residentiai risk-based cleanup level.
•

Test Trench PRST08 - RDX was detected in subsurface soil samples (3-3.5 ft bgs) in
concentrations (340-440 µg/g) that exceed the caIculated non-residential risk-based cleanup level.

Static Eiection Test Site/Backstop Berm: Lead (1,400 - 150, 000 µg/g) was detected above the NDEQ
TBC Guidance of 400 mg/Kg. The samples were collected from PRSL11, PRSL12, and PRSL13. It
should be noted that this area was not addressed in the FS because it is currently being used as a
firing range by the local police department.
7.3

DESCRIPTION OF ALTERNATIVES

Based on the findings of the RI, a FS was prepared in 1997 to address lead and RDX contamination
at the Pistol Range. Provided below are remedial alternatives for addressing RDX- and lead-contaminated soil
at the Burning Pit Area. The assessment consists of evaluating each alternative using the nine criteria listed
in the NCP.
7.3.1

Alternative 1: No Action
Description: According to the NCP, the level of treatment achieved must be compared to the required
expenditures of time and materials as an integral portion of the remedy selection process. The "No
Action" alternative is intended to serve as a baseline with which to compare the risk reduction
effectiveness of other potential alternatives.
Overall Protection of Human Health and the Environment: The "No Action" alternative does not
decrease the potential risks to humans or the environment in any way, as no remedial activities will
be implemented at the site under this alternative. Ingestion or dermal exposure to lead and RDX
contamination in soil are potential exposure pathways for workers at the site. Implementation of the
"No Action" alternative would not reduce pathways for lead or RDX exposure to humans.
Compliance with ARARs: This alternative does not comply with chemical-specific TBC guidance for
RDX and lead. The location-specific and action-specific ARARs are not considered because no
remedial activities will be implemented at the site.
Long-term Effectiveness and Permanence: Over the long-term, this alternative will not be effective. No
actions are taken to provide permanent human health and environmental protection.
Reduction of Toxicity, Mobility, or Volume Through Treatment: There will be no further remedial
activities implemented at the site; subsequently, there will be no further reduction of toxicity, mobility,
or volume through treatment.
Short-term Effectiveness: There is no short-term effectiveness associated with the "No Action"
alternative because no additional remedial activities will be implemented at the site.
Implementability: There are no implementability concerns associated with the "No Action" alternative
because no remediation activities will be conducted at the site.
Cost: Because contaminants are left in place, a site evaluation report must be submitted after five
years. The estimated present worth of this alternative is $37,240, the cost of the five-year report.

7.3.2

Alternative 2: Deed Restriction and Groundwater Monitoring
Description: The institutional controls alternative establishes legal and barrier restrictions on the use
of land and groundwater as an attempt to reduce the dangers from releases or threatened releases of
environmental contaminants. The components of this alternative include:
•

Monitoring: Monitoring of groundwater would be initiated and maintained for a period of 30 years.
Groundwater would be monitored through a system consisting of three existing wells

DAAA15-91-D-0014
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October 1999

7-4

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 7.0
Pistol Range

and two new wells. The water will be sampled semi-annually and will be analyzed for lead and
RDX.
•

Deed Restriction: This alternative also includes implementation of deed restrictions to prevent
residential use. The deed restrictions will also specifically identify the location and condition of the
eight burn pits in accordance with DOD 6055.9-STD Chapter 12. The deed restrictions will include
proprietary institutional controls restricting the future use of the property such as easements or
restrictive covenants that are legally enforceable against subsequent property owners and
instituted, depending on state law, by conveyance or contract. The U.S. Army will be responsible
for implementing and maintaining the effectiveness of the institutional controls.

Overall Protection of Human Health and the Environment: Protection of human health from exposure
to RDX and lead is achieved by the implementation of site restrictions. However, this alternative does
not mitigate migration of contaminants into groundwater. Because groundwater is not protected, this
alternative does not comply with this criteria.
Compliance with ARARs: There would be no location-specific or action-specific ARARs associated
with this alternative at the site. This alternative does not involve cleanup of RDX- and lead-contaminated
soils; therefore, this alternative does not meet chemical-specific TBC guidance.
Long-term Effectiveness and Permanence: No treatment related residuals are generated. All existing
waste is left untreated, and the magnitude of risk posed by the site goes unchanged. Therefore, this
alternative does not afford long-term protection of human health.
Reduction of Toxicity, Mobility, or Volume through Treatment: This alternative provides no reduction
in toxicity, mobility, or volume of the contaminated soil "through treatment.”
Short-term Effectiveness: Because no soil will be removed, this alternative creates no additional risks
to the community, workers, or the environment due to remedial activities. Installation of wells would not
cause risk to workers or the environment.
Implementability : The technical feasibility of implementing Alternative Two is considered to be high
because the required activities (monitoring and site control) are easily implemented. Actions to be
taken are limited to the addition of warning signs, the prevention of site and groundwater usage to be
regulated by the Army, and the implementation of a comprehensive monitoring program.
Cost: The capital cost and annual O&M costs for Alternative Two are approximately $70,000 and
$150,000, respectively. The estimated 30-year present worth at a 5% interest rate is $293,880.
7.3.3

Alternative 3: Excavation and Off-site Disposal of Soil from Test Trenches PRST07 and
PRST08 and Deed Restriction to Prevent Residential Use
Description: Lead- and RDX-contaminated soil from Test Trench PRST07 and RDX- contaminated soil
from Test Trench PRST08 would be removed to cleanup levels. The test trenches are approximately
4 ft by 40 ft in area. Test Trench PRST07 will be excavated to a depth of 3 ft bgs and Test Trench
PRST08 will be excavated to a depth of 4.5 ft bgs. Therefore, a volume of 18 yd3 from PRST07 and 27
yd3 from PRST08 would be removed. Prior to excavation, soil will be screened for UXO. No shoring or
dewatering would be required, as the depth of excavation is less than 5 ft bgs. It should be noted that
the pits were delineated and excavated as part of a test trench exercise in 1995. Upon completion of
the soil excavation, lead screening using x-ray fluorescence (XRF) in Test Trench PRST07 and RDX
screening using immunoassay in Test Trenches PRST07 and PRST08 would be used to determine if
excavation of soil to cleanup levels has been completed. If screening data indicate that removal of lead
(Test Trench PRST07, only) and RDX to cleanup levels has been accomplished, samples would be
collected for confirmational analysis. Samples would be collected and tested to determine if excavated
soil is a RCRA-hazardous waste. Please note that the cost estimates are conservative (i.e., disposal
costs are for incineration at a RCRA permitted facility). The excavated area would be backfilled with
clean soil (approximately 55 yd3) and reseeded.

DAAA15-91-D-0014
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October 1999

7-5

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 7.0
Pistol Range

This alternative also includes implementation of deed restrictions to prevent residential use. The deed
restrictions will also specifically identify the location and condition of the eight burn pits in accordance
with DOD 6055.9-STD Chapter 12. The deed restrictions will include proprietary institutional controls
restricting the future use of the property such as easements or restrictive covenants that are legally
enforceable against subsequent property owners and instituted, depending on state law, by
conveyance or contract. The U.S. Army will be responsible for implementing and maintaining the
effectiveness of the institutional controls.
Overall Protection of Human Health and the Environment: The removal of lead and RDX contaminated
soil to the cleanup levels of 400 µg/g and 52 µg/g, respectively, from the test trenches is protective of
human health under non-residential conditions.
Compliance with ARARs:
•

Chemical-specific ARARs/TBC guidance: The excavation would meet the chemical-specific TBC
guidance for RDX which is the calculated risk-based level and for lead, which is the NDEQ
guidance level considered to be protective of human health under non-residential conditions.

•

Location-specific ARARs: This alternative is not expected to affect any location-specific ARARS.

•

Action-specific ARARs: The proposed remedial design and operation should meet all actionspecific ARARs.

Long-term Effectiveness and Permanence: Over the long-term, this alternative would be effective
because lead and RDX are removed to levels that are below their respective cleanup levels.
Reduction of Toxicity, Mobility, or Volume through Treatment: Toxicity, mobility, and volume will be
reduced for the soil medium since the contaminated soil will be removed and disposed at an off-site
disposal facility.
Short-term Effectiveness: If selected as the remedial action, excavation could be implemented in less
than six months. This alternative poses minimal risk to the community, workers, or the environment
during its implementation. Workers involved with the waste excavation and processing activities could
be exposed to risks associated with dermal contact with contaminated soil along with some risks from
breathing contaminant dust and vapors. Emission levels, however, will be low, and workers will be
protected by use of appropriate personal protective equipment. No endangered species are to be
affected during remediation.
Implementability: Equipment and materials for implementing this alternative are readily available.
Cost: Capital and O&M costs associated with this alternative are estimated to be $142,787 and
$28,000, respectively. The estimated 30-year present worth at a 5% interest rate is $227,147.
7.4

SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES FOR THE PISTOL RANGE

As required by CERCLA, the remedial alternatives described above were evaluated using nine criteria
specified by USEPA. This section summarizes the relative performance of each of the alternatives with respect
to the nine CERCLA evaluation criteria. Table 7-1 summarizes the comparative analysis for the three remedial
alternatives provided in the FS.

DAAA15-91-D-0014
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October 1999

7-6

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 7.0
Pistol Range
Table 7-1. Comparative Analysis of Remedial Action Alternatives
NCP
Criteria

Alternative 1
No Action

Pistol Range

Alternative 2
Monitoring of Groundwater
and Deed Restriction

Alternative 3
Excavation and Off-Site
Disposal of Lead- and RDXContaminated Soil and
Deed Restriction

1. OVERALL PROTECTIVENESS
Direct Contact/Soil Ingestion

No significant reduction in
risk. Contaminant levels
remain in soil.

Deed restrictions limit exposure to
contaminated soil; however,
contaminants remain in place.

All contamination above levels
causing risk will be removed.

2. COMPLIANCE WITH ARARS/TCB GUIDANCE
Chemical-Specific ARARS

There are no chemicalspecific ARARs.

See Alternative 1.

See Alternative 1.

Location-Specific ARARs

There are no locationspecific ARARs.

See Alternative 1.

Would meet all location-specific
ARARs.

Action-Specific ARARs

There are no actionspecific ARARs.

See Alternative 1.

Would meet all action-specific
ARARs.

TBC Guidance

Does not meet TBC
cleanup levels.

See Alternative 1.

Reduces lead and RDX levels in soil
to below cleanup levels.

3. LONG-TERM EFFECTIVENESS AND PERMANENCE
Magnitude of Residual Risk
(Direct Contact/Soil Ingestion)

Source has not been
removed. Existing risk will
remain.

Source has not been removed.
Existing risk will remain.

Risk is eliminated since source is
removed.

Adequacy and reliability of
Controls

No controls over existing
contamination.

Access restrictions reduce some
contact with contaminated soil.
However, exposure remains.

Reliability of soil removal high, since
all RDX and lead above remedial
goals will be removed from the site.

Need for 5-Year Review

Yes.

Yes.

Yes.

4. REDUCTION IN TOXICITY, MOBILITY, AND VOLUME THROUGH TREATMENT
Treatment Process Used

None.

None.

Incineration and stabilization.

Amount Destroyed or Treated

None.

None.

45 yd3.

Reduction of Toxicity, Mobility,
or Volume

None.

None.

Toxicity, mobility, and volume is
reduced.

Irreversible Treatment

None.

None.

Incineration is irreversible.

Type and Quantity of Residuals
Remaining after Treatment

No residuals remain.

No residuals remain.

RDX would be completely oxidized
by incineration. Lead in the residual
ash may require stabilization.

Statutory Preference for
Treatment

Does not satisfy.

Does not satisfy.

Satisfies.

Community Protection

Risk to community not
increased by remedy
implementation.

See Alternative 1.

See Alternative 1.

Worker Protection

No significant risk to
workers.

No significant risk to workers.

Protection required against dermal
contact and inhalation of
contaminated dust during excavation
activities.

Environmental Impacts

Continued impact from
existing conditions.

Continued impact from existing
conditions.

No environmental impacts from
remedial action.

Time until Action is Complete

Not applicable.

Until agreement is reached among
stakeholders that monitoring is no
longer necessary.

Six months.

Ability to Obtain Approvals and
Coordinate with other Agencies

No approval necessary.

Yes.

Yes.

Availability of Services and
Capacities

No services or capacities
necessary.

Services and capacities are readily
available.

See Alternative 2.

Availability of Equipment,
Specialists, and Materials.

None required.

Equipment, specialists, and
materials are readily available.

See Alternative 2.

Availability of Technologies.

None required.

Yes.

Excavation, disposal, stabilization
and incineration technologies readily
available.

5. SHORT-TERM EFFECTIVENESS

6. IMPLEMENTABILITY

DAAA15-91-D-0014
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October 1999

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Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 7.0
Pistol Range
Table 7-1. Comparative Analysis of Remedial Action Alternatives
NCP
Criteria

Alternative 1
No Action

Pistol Range

Alternative 2
Monitoring of Groundwater
and Deed Restriction

Alternative 3
Excavation and Off-Site
Disposal of Lead- and RDXContaminated Soil and
Deed Restriction

7. COST
Capital Cost

$0

$70,000

$142,787

O&M Cost

$28,000

$150,962

$28,000

Present Worth Cost

$37,240

$293,880

$227,147

7.4.1

Protection of Human Health and the Environment

Current levels of contamination pose levels of human health risk that may be considered unacceptable.
RDX was detected at concentrations greater than the non-residential risk-based cleanup level (52 µg/g). Lead
was detected above the NDEQ TBC chemical-specific guidance. Alternative One will not meet this criterion
because no actions are taken to eliminate, reduce or control exposure pathways. Alternative One does not
achieve the threshold criterion of protection of human health and the environment.
Alternative Two provides some protection from contaminated soil by implementing and maintaining deed
restrictions, which would prohibit the use of the test trenches and immediate area for agricultural use. Although
the deed restriction will limit dermal and ingestion exposure to contaminants in soil (humans only), it does not
prevent further contaminant loading to groundwater; therefore, Alternative Two is not fully protective of human
health and the environment.
Alternative Three provides protection of human health and the environment by eliminating the surface
soil exposure pathway as well as mitigating migration of RDX and lead into groundwater (sources are removed).
Therefore, implementation of this alternative would allow future land use of the Pistol Range area for
non-residential purposes. Alternative Three is considered protective of human health because RDX and lead in
soil would be removed to concentrations that correlate with the cleanup levels of 52 µg/g and 400 µg/g,
respectively.
7.4.2

Compliance with ARARs

Compliance with ARARs is a threshold criterion, which must be met by the proposed remedial action.
Alternatives One and Two do not meet the chemical-specific TBC guidance because contaminant levels remain
in soil. Alternative Three involves further actions to eliminate exposure to contaminated soil and mitigate
migration of contaminants into soil. These actions can be performed in compliance with the action- and
location-specific ARARs as identified in Table 7-2. This is the only alternative that completely meets
chemical-specific TBC guidance.
7.4.3

Long-term Effectiveness and Permanence

Alternatives One and Two do not provide long-term effectiveness and permanence. Neither of these
alternatives provides sufficient, effective protection of groundwater. Alternative Three provides long-term
prevention of exposures to contaminated soil and migration of contaminants into groundwater because sources
are removed.
Reviews at least every five years, as required, would be necessary to evaluate the effectiveness of any
of these alternatives because hazardous substances would remain onsite in concentrations above health-based
levels.
7.4.4

Reduction of Toxicity, Mobility or Volume through Treatment

Alternatives One and Two do not provide reduction of toxicity, mobility, or volume of the contaminants.
Alternative Three provides reduction of toxicity, mobility, and volume because all RDX and lead in the soil are
removed to below cleanup levels. If off-site incineration were the off-site disposal option, RDX would be
permanently destroyed through treatment. The remaining ash would be stabilized for any inorganics that may
be present.
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TEPS14-14
October 1999

7-8

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 7.0
Pistol Range
Table 7-2. ARARs and TBC Guidance for Preferred Alternative for Excavation, Off-Site Disposal of
RDX- and Lead-Contaminated Soil, and Deed Restriction to Prevent Residential Use
Action-Specific ARARS
Excavation
Regulations to processing machines and equipment (NDEC Title 129 Chapter 4)
Dust generation during construction activities (NDEC Title 129 Chapter 17)
Disposal or decontamination of equipment, structures, etc. (40 CFR 264.114)
On-site health and safety for personnel during remedial actions (29 CFR 1910)
Closure and Post-Closure
Clean Closure (40 CFR 264.111)
Closure with Waste in Place (40 CFR 264.228)
Post-Closure Care (40 CFR 264.117)
Disposal of Soil
Hazardous Waste Determination (40 CFR 261)
Standards for generators (40 CFR 262)
Standards for transporters (40 CFR 263, NDEC Title 128, Ch 3 and Ch 17, and 49 CFR 171)
LDRs and Treatment Standards (40 CFR 268)
Location-Specific ARARs
Presence of those species listed in the Endangered Species Act (16 USC 1351 et seq.), the Fish and Wildlife Coordination Act (16 USC 661 et
seq.), 40 CFR 6.302(h), 50 CFR 402, CWA 404, and 40 CFR 231.10(b), and RSN 37-430 to -438 as being rare, threatened or endangered.
Presence of farmlands as defined under 7 CFR 658.4 and 658.5 and the Farmland Protection Policy Act (7 USC 4201 et seg.)
Chemical-Specific TBC Guidance ARARs
Lead: NDEQ TBC Guidance (400 mg/kg) Protective of Human Health Under Non-Residential Conditions
RDX: Calculated Risk-based Cleanup Level (52 mg/kg)

7.4.5

Short-term Effectiveness

Short-term effectiveness is not applicable to Alternative One. Alternative Two provides for short-term
protection of workers during implementation. Workers will take appropriate safety measures to perform their
functions (e.g., drilling, sampling). For Alternative Three, the use of proper dust suppressant measures will
control windblown emissions of contaminated dust to protect the community and on-site workers. Proper
personal protective equipment would be required for site workers. Measures to protect the environment are not
expected for implementing Alternatives Two and Three.
The length of time required for implementing and completing the remedial alternatives is as follows:
Alternative One is a "No Action" alternative; therefore, no time is required; Alternative Two would require less
than three months to implement; and Alternative Three will take less than six months to implement.
7.4.6

Implementability

Alternatives One and Two are the most easily implemented. Alternative One is a no further action
alternative. Alternative Two involves the installation of monitoring wells and sampling. Alternative Three would
also be fairly easy to implement because it uses commonly available equipment and materials. Alternative
Three involves excavation and off-site incineration or landfilling of contaminated soils. Excavation to the depths
proposed in Alternative Three would be easy to implement. The excavation (approximately 5 ft bgs) would not
require shoring or dewatering.
7.4.7

Cost

Total capital and annual costs and present worth (discount rate of 5%) for each alternative are
presented in Table 7-3. The progression of total present worth from least expensive to most expensive is:
Alternative One, Alternative Three, and Alternative Two.
7.5

SELECTED REMEDY

The selected remedy to address the soil contamination at the Pistol Range is Alternative Three Excavation, Off-Site Disposal of RDX- and Lead-Contaminated Soil, and Deed Restriction to Prevent Residential
Use. Alternative Three is the preferred alternative for the Pistol Range because it provides the best balance of
features that offer overall protection to human health under non-residential conditions; is easy to implement;
and involves minimal risks to site workers. The deed restrictions will also

DAAA15-91-D-0014
TEPS14-14
October 1999

7-9

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 7.0
Pistol Range

specifically identify the location and condition of the eight burn pits in accordance with DOD 6055.9-STD
Chapter 12. The deed restrictions will include proprietary institutional controls such as easements or restrictive
covenants that are legally enforceable against subsequent property owners and instituted, depending on state
law, by conveyance or contract. The U.S. Army will be responsible for implementing and maintaining the
effectiveness of the institutional controls. Table 7-2 presents ARARs and TBC guidance for Alternative Three.
Table 7-3 presents a detailed cost estimate for the preferred alternative. Exhibit 7-3 presents Alternative Three.
Table 7-3. Cost Estimate for Preferred Alternative for Excavation, Off-Site Disposal of
RDX- and Lead- Contaminated Soil, and Deed Restriction to Prevent Residential Use
Remedial Action
Capital
Work Plan
Pre-Construction Meeting
Site Mobilization
Site Setup
Clearing and Grubbing
Contaminated Soil Removal (Excavation)
UXO Screening
Analysis
Waste Characterization
Soil Disposal Arrangements
Waste Characterization
Waste Disposal
Soil Transportation (RDX Contamination)
Decontamination Water
Spent PPE
Disposal Arrangements
Post Excavation Sampling
Total Lead And RDX
XRF Screening
Immunoassay (RDX)
Labor
Site Restoration
Backfilling With Clean Soil
Top Soil
Grading And Seeding
Demobilization
Closure Report
Deed Restriction

Units
Report
Meeting
Site
Site
Site
Site
Site

No.
1
1
1
1
1
1
1

Unit Price
$17,250.00
$6,960.00
$5,000.00
$2,000.00
$800.00
$11,140.00
$25,200.00

$17,250.00
$6,960.00
$5,000.00
$2,000.00
$800.00
$11,140.00
$25,200.00

$2,560.00

$2,560.00
$677.00
$2,560.00

Site

5

Ton
55-Gal
Drum
55-Gal
Drum
Site

68
1

$515.00
$130.00

$34,762.00
$130.00

1

$130.00

$130.00

1

$677.00

$677.00

Sample
Week
Sample
Day

10
1
1
1

$285.00
$2,000.00
$18.00
$650.00

$2,850.00
$2,000.00
$18.00
$650.00

CY
CY
SY
Site
Report
Each

2.50
2.50
11.0
1
1
1

$15.00
$30.00
$2.00
$5,000.00
$9,125.00
$5,000.00
Subtotal

$37.00
$75.00
$22.00
$5,000.00
$9,125.00
$5,000.00
$142,787.00

$10,000.00

$10,000.00
$28,000.00
$28,000.00
$170,787.00
$42,697.00
$13,663.00
$227,147.00

O & M Cost
5-Year Site Review (30-Year Period)
Each
Present Worth 5-Year Site Reviews (30-Year Period @ 5%)

1

Subtotal O & M Cost
Subtotal Cost of Alternative
Contingency (@ 25%)
Project Management (@ 8%)
Total Cost Alternative

7.6

Cost

EXPLANATION OF SIGNIFICANT CHANGES

The Proposed Plan presents the selected remedy as the preferred alternative. No significant changes
have been made.

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TEPS14-14
October 1999

7-10

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 8.0

SANITARY LANDFILL

8.1

OPERATIONAL HISTORY

Four Potential Units of Contamination (PUCs) have been identified at the site based on analysis of
aerial photographs and historical documents. Below are the AOCs investigated in the RI/FS.
•

Disposal Area PUC: includes the Sanitary Waste Disposal Area, the Burning Cage Area, the
Capped Landfill Area, the Flammable Liquids Disposal Area, and the Metal Disposal Area.

•

Destruction Area PUC: includes the Fuse Destruction Area and the Explosive Parking Area.

•

IRA Site 2 PUC.

•

Freon-Contaminated Groundwater PUC.

In addition, four ditches at the Sanitary Landfill were sampled for contaminants. Two of the ditches are
upgradient. Two of the ditches are adjacent to the explosives parking area.
Use of the Sanitary Landfill area was stopped in 1988. The landfill is currently closed and the area is
covered with vegetation.
8.2

FINDINGS OF THE REMEDIAL INVESTIGATION

The sampling program at the Sanitary Landfill was as follows: geophysical survey and surface soil
sampling for the 1991 EA; geophysical survey, surface soil sampling, subsurface soil sampling, test trench
excavation, and groundwater sampling for the 1993 SCD; and surface soil sampling, subsurface soil sampling,
and groundwater screening and sampling for the 1996 RI. Exhibit 8-1 presents the sampling locations from past
investigations at the Sanitary Landfill. For the types of compounds that were analyzed for, refer to the
Investigative Program Summary of the 1996 RI. Exhibit 8-2 displays the locations where COPCs were detected
in soil above the calculated non-residential risk-based cleanup levels. Only the Fuse Destruction Area
contained contamination considered above levels considered a risk to humans under non-residential conditions.
RDX was detected at the northwestern corner of the Fuse Destruction Area at a concentration of 890 µg/g. The
detection of RDX above the calculated risk-based cleanup level triggered the need for an alternatives analysis.
Provided in Section 8.3 are the summaries of the remedial alternatives presented in the FS.
8.3

REMEDIAL ALTERNATIVES

8.3.1

Alternative 1: No Action.
Description: According to the NCP, the level of treatment achieved must be compared to the required
expenditures of time and materials as an integral portion of the remedy selection process. The "No
Action" alternative is intended to serve as a baseline with which to compare the risk reduction
effectiveness of other potential alternatives.
Overall Protection of Human Health and the Environment: The No Action alternative does not decrease
the potential risks to humans or the environment in any way, as no remedial activities will be
implemented at the site under this alternative. Ingestion or dermal exposures to RDX contamination
in surface soil are potential exposure pathways for humans at the site.
Compliance with ARARs: This alternative does not comply with chemical-specific TBC guidance.
Location-specific and action-specific ARARs are not considered because no remedial activities will be
implemented at the site.
Long-term Effectiveness and Permanence: Over the long-term, this alternative will not be effective. No
actions are taken to provide permanent human health and environmental protection.
Reduction of Toxicity, Mobility, or Volume Through Treatment: There will be no further remedial
activities implemented at the site; subsequently, there will be no further reduction of toxicity, mobility,
or volume through treatment.

DAAA15-91-D-0014
TEPS14-14
October 1999

8-1

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

  


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Section 8.0
Sanitary Landfill

Short-term Effectiveness: There is no short-term effectiveness associated with the No Action
alternative because no additional remedial activities will be implemented at the site.
Implementability: Not applicable.
Cost: Because contaminants are left in place, a site evaluation report must be submitted after five
years. The estimated 30-year present worth of this alternative is $37,240, the cost of the 5-year report.
8.3.2

Alternative 2: Groundwater Monitoring and Deed Restriction
Description: This alternative includes semi-annual monitoring of groundwater from two wells, located
upgradient and downgradient of the landfill. This alternative also includes implementation of deed
restrictions to prevent residential use. The deed restrictions will include proprietary institutional controls
restricting the future use of the property such as easements or restrictive covenants that are legally
enforceable against subsequent property owners and instituted, depending on state law, by
conveyance or contract. The U.S. Army will be responsible for implementing and maintaining the
effectiveness of the institutional controls.
Overall Protection of Human Health and the Environment: This alternative does not decrease the
potential risks to humans or the environment in any way, as no remedial activities will be implemented
at the site under this alternative. The baseline risk assessment indicates that the risks posed by
potential exposure pathways are above the acceptable risk range. Therefore, this alternative does not
satisfy this criterion.
Compliance with ARARs: The TBC guidance for removing RDX to the risk-based cleanup level would
not be met by this alternative.
Long-term Effectiveness and Permanence: Since no remedial actions are taken, this alternative will
not provide permanent human health and environmental protection.
Reduction of Toxicity, Mobility, or Volume Through Treatment: There will be no further remedial
activities implemented at the site; subsequently, there will be no further reduction of toxicity, mobility,
or volume through treatment.
Short-term Effectiveness: There is no short-term effectiveness associated with this alternative,
because no additional remedial activities will be implemented at the site.
Implementability: Since this alternative includes only monitoring activities, it is easy to implement.
Cost: The capital cost and annual O&M costs for Alternative Two are approximately $70,000 and
$104,650, respectively. The estimated 30-year present worth is $232,285.

8.3.3

Alternative 3: Excavation, Off-Site Disposal of RDX-Contaminated Soil, and Deed Restriction
to Prevent Residential Use
Description: RDX-contaminated soil at the northwestern corner of the Fuse Destruction Area would
be removed to or below the risk-based cleanup level (52 µg/g). A square area of approximately 225 ft 2
would be excavated from around soil sample SLFL017 to 1 ft bgs. Upon completion of the soil
excavation, RDX screening using immunoassay would be used to determine if excavation of soil to the
cleanup level has been completed. If screening data indicate that removal of RDX to the cleanup level
has been accomplished, samples would be collected for confirmational analysis. The excavated soil
would be placed in a 20-ton capacity roll-off. The soil would be transported to a RCRA-permitted
incinerator that can accept wastes from a CERCLA site. The excavated areas would be backfilled with
clean soil and reseeded. Provided below are the components of the excavation/off-site disposal
alternative.
This alternative also includes implementation of deed restrictions to prevent residential use. The deed
restrictions will include proprietary institutional controls restricting the future use of the property such
as easements or restrictive covenants that are legally enforceable against subsequent property owners
and instituted, depending on state law, by conveyance or contract. The U.S. Army will be responsible
for implementing and maintaining the effectiveness of the institutional controls.

DAAA15-91-D-0014
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October 1999

8-4

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 8.0
Sanitary Landfill

Overall Protection of Human Health and the Environment: The removal of RDX-contaminated soil to the
risk-based cleanup level of 52 µg/g is protective to humans under non-residential conditions.
Compliance with ARARs
•

Chemical-specific ARARs/TBC guidance: The alternative would remove RDX to levels below the
calculated risk-based cleanup level considered protective of human health under non-residential
conditions.

•

Location-specific ARARs: This alternative is not expected to affect any location-specific ARARs.

•

Action-specific ARARs: The proposed remedial design and operation should meet all requirements
presented in Table 8-2.

Long-term Effectiveness and Permanence: Over the long-term, excavation of the RDX-contaminated
would be effective because the RDX is removed to below the calculated risk-based cleanup level.
Reduction of Toxicity, Mobility, or Volume Through Treatment: Toxicity, mobility, and volume will be
reduced for the soil medium since the RDX-contaminated soil will be removed and incinerated at an
off-site treatment facility.
Short-term Effectiveness: If selected as the remedial action, excavation could be implemented in less
than six months. This alternative poses minimal risk to the community, workers, or the environment
during its implementation. Workers involved with the waste excavation and processing activities could
be exposed to risks associated with dermal contact with contaminated soil along with some risks from
breathing dust and vapors. However, the emission levels will be low, and workers will be protected by
use of appropriate personal protective equipment.
Implementability: No permits are required for on-site activities, but the off-site disposal facility must
be permitted. The waste shipment must be manifested and transported by a licensed hazardous waste
transporter. Equipment and materials for implementing this alternative are readily available.
Cost: The capital and O&M costs for Alternative Three are estimated to be approximately $71,419 and
$28,000, respectively. The estimated present worth is $132,228.
8.4

SUMMARY OF COMPARATIVE ANALYSIS OF SANITARY LANDFILL ALTERNATIVES

As required by CERCLA, the remedial alternatives described above were evaluated using nine criteria
specified by USEPA. This section summarizes the relative performance of each of the alternatives with respect
to the nine CERCLA evaluation criteria. Table 8-1 summarizes the comparative analysis for the three
alternatives provided in the FS.
Table 8-1. Comparative Analysis of Remedial Action Alternatives S Sanitary Landfill
NCP
Criteria

Alternative 1
No Action

Alternative 2
Monitoring of Groundwater
and Deed Restriction

Alternative 3
Excavation, Off-Site
Disposal
of RDX- Contaminated
Soil, Deed Restriction to
Prevent Residential Use

No significant reduction in
risk. Contaminant levels
remain in soil.

Reduces exposure with soil
media; however, contaminants
remain in soil.

Risk reduced to below
acceptable levels for nonresidential use.

See Alternative 1.

See Alternative 1.

1. OVERALL PROTECTIVENESS
Direct Contact/Soil
Ingestion

2. COMPLIANCE WITH ARARS/TBC GUIDANCE
Chemical-Specific
There are no chemicalARARS
specific ARARs.
Location-Specific ARARs

There are no
location-specific ARARs.

See Alternative 1.

Would meet all
location-specific ARARs.

Action-Specific ARARS

There are no
action-specific ARARs.

See Alternative 1.

Would meet all
action-specific ARA S

DAAA15-91-D-0014
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October 1999

8-5

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 8.0
Sanitary Landfill
Table 8-1. Comparative Analysis of Remedial Action Alternatives
NCP
Criteria

TBC Guidance

Alternative 1
No Action

Sanitary Landfill

Alternative 2
Monitoring of Groundwater
and Deed Restriction

Does not meet TBC
Cleanup levels.

Alternative 3
Excavation, Off-Site Disposal
of RDX- Contaminated Soil,
Deed Restriction to Prevent
Residential Use

See Alternative 1.

Reduces RDX levels in soil to
below cleanup levels.

3. LONG-TERM EFFECTIVENESS AND PERMANENCE
Magnitude of Residual Risk
(Direct Contact/Soil
Ingestion)

Existing risk will remain.

See Alternative 1.

Risk is minimized since source is
removed.

Adequacy and Reliability of
Controls

No controls over remaining
contamination.
No reliability.

See Alternative 1.

Reliability of soil removal high,
since all RDX above remedial
goals will be removed from the
site.

Need for 5-Year Review

Yes.

Yes.

Yes.

4. REDUCTION IN TOXICITY, MOBILITY, AND VOLUME THROUGH TREATMENT
Treatment Process Used

None.

None.

Incineration.

Amount Destroyed or
Treated

None.

None.

8.3 yd3.

Reduction of Toxicity,
Mobility, or Volume

None.

None.

Toxicity, mobility, and volume
are reduced.

Irreversible Treatment

None.

None.

Incineration is irreversible.

Type and Quantity of
Residuals Remaining after
Treatment

No residuals remain.

No residuals remain.

Incinerated soils remain, but are
expected to be nonhazardous.
No residual.

Statutory Preference for
Treatment

Does not satisfy.

Does not satisfy.

Satisfies.

Community Protection

Risk to community no increased
by remedy implementation.

See Alternative 1.

See Alternative 1.

Worker Protection

No significant risk to workers.

No significant risk to workers.

Protection required against
dermal contact and inhalation of
contaminated dust during
excavation activities.

Environmental Impacts

Continued impact from existing
conditions.

Continued impact from existing
conditions.

No environmental impacts from
remedial action.

Time until Action is Complete

Not applicable.

Until agreement is reached
between stakeholders that
monitoring is no longer
necessary.

Six months.

Ability to Obtain Approvals
and Coordinate with other
Agencies

No approval necessary.

See Alternative 1.

Yes.

Availability of Services and
Capacities

No services or capacities
necessary.

See Alternative 1.

Services available.

Availability of Equipment,
Specialists, and Materials.

None required.

See Alternative 1.

Equipment available.

Availability of Technologies.

None required.

None Required.

Excavation, disposal, and
incineration technologies readily
available.

5. SHORT-TERM EFFECTIVENESS

6. IMPLEMENTABILTY

7. COST
Capital Cost

$0

$70,000

$71,419

O&M Cost

$28,000

$104,650

$28,000

Present Worth Cost

$37,240

$232,285

$132,228

8.4.1

Protection of Human Health and Environment

Current levels of RDX contamination pose levels of human health risk that may be considered
unacceptable. Explosives compound RDX was detected in one location at a concentration greater than the
risk-based cleanup level considered protective of human health under non-residential conditions. Alternative One
will not meet this criterion because no actions are taken to eliminate, reduce or control
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Final Document

 Section 8.0
Sanitary Landfill

exposure pathways. Alternative One does not achieve the threshold criterion of protection of human health and
the environment.
Alternative Two provides some protection from contaminated soil by implementing and maintaining deed
restrictions that would prohibit the use of the immediate area for agricultural use. Although the deed restriction
will limit dermal and ingestion exposure to contaminants in soil (humans only), it does not prevent further
contaminant loading to groundwater; therefore, Alternative Two is not fully protective of human health under
non-residential conditions.
Alternative Three provides protection of human health and the environment by eliminating the surface
soil exposure pathway as well as mitigating migration of RDX into groundwater (source is removed). Therefore,
implementation of this alternative would allow future land use of the Sanitary Landfill area. Alternative Three is
considered protective of human health under non-residential conditions because RDX in soil would be removed
to below the risk-based cleanup level.
8.4.2

Compliance with ARARs

Compliance with ARARs is a threshold criterion that must be met by the proposed remedial action.
Alternatives One and Two do not meet the chemical-specific TBC guidance because RDX levels remain in soil
above the risk-based cleanup level. Alternative Three involves further actions to eliminate exposure to
contaminated soil and mitigate migration of contaminants into groundwater. These actions can be performed
in compliance with the action- and location-specific ARARs. This is the only alternative that completely meets
chemical-specific TBC guidance.
8.4.3

Long-term Effectiveness and Permanence

Alternatives One and Two do not provide long-term effectiveness and permanence. Neither of these
alternatives provides sufficient, effective protection of groundwater and risk to humans from exposure to
contaminated soils. Alternative Three provides long-term prevention of exposures to contaminated surface soil
and migration of contaminants into groundwater because sources are removed.
Reviews at least every five years, as required, would be necessary to evaluate the effectiveness of any
of these alternatives because hazardous substances would remain onsite in concentrations above health-based
levels.
8.4.4

Reduction of Toxicity, Mobility or Volume through Treatment

Alternatives One and Two do not provide reduction of toxicity, mobility, or volume of the contaminants.
Alternative Three provides reduction of toxicity, mobility, and volume because all RDX in soil is removed to a
level lower than the risk-based cleanup level. As the RDX contaminated soil would be disposed of by off-site
incineration, RDX would be permanently destroyed through treatment.
8.4.5

Short-term Effectiveness

Short-term effectiveness is not applicable to Alternative One. Alternative Two provides for short-term
protection of workers during implementation. Workers will take appropriate safety measures to perform their
functions (e.g., drilling, sampling). For Alternative Three, the use of proper dust suppressant measures will
control windblown emissions of contaminated dust to protect the community and on-site workers. Proper
personal protective equipment would be required for site workers. Because of the location of the Sanitary
Landfill, short-term effectiveness to the public is not applicable for Alternatives Two and Three. Measures to
protect the environment are not expected for implementing Alternatives Two and Three.
8.4.6

Implementability

Alternatives One and Two are the most easily implemented. Alternative One is a no further action
alternative. Alternative Two involves the installation of monitoring wells and sampling. Alternative Three would
also be fairly easy to implement because it uses commonly available equipment and materials. Alternative
Three involves excavation and off-site incineration of contaminated soils.
The length of time required to implement and complete the remedial alternatives are as follows:
Alternative One is a "No Action" alternative, therefore, no time is required; Alternative Two would require less
than three months to implement; and Alternative Three could be implemented in six months.
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Final Document

 Section 8.0
Sanitary Landfill

8.4.7

Cost

Total capital and annual costs and present worth (discount rate of 5%) for each alternative are
presented in Table 8-1. The progression of total present worth from least expensive to most expensive
alternative is: Alternative One, Alternative Three, and Alternative Two.
8.5

SELECTED REMEDY

The selected remedy is Excavation, Off-Site Disposal of RDX-Contaminated Soil, and Deed Restriction
to Prevent Residential Use – Alternative Three (Exhibit 8-3). This is the preferred alternative for the Sanitary
Landfill because it provides the best balance of features that offer overall protection to human health and the
environment. Excavation of contaminated soils will remove risk to human health under non-residential
conditions. The deed restrictions will include proprietary institutional controls such as easements or restrictive
covenants that are legally enforceable against subsequent property owners and instituted, depending on state
law, by conveyance or contract. The U.S. Army will be responsible for implementing and maintaining the
effectiveness of the institutional controls. In addition, this action is easy to implement, involves minimal risks
to site workers, and should comply with all action- and location-specific ARARs during implementation. Table
8-2 presents ARARs and TBC guidance for Alternative Three. Table 8-3 provides a detailed cost estimate for
Alternative Three.
Table 8-2. ARARs and TBC Guidance for Alternative 3
Action-Specific ARARs
Excavation
Regulations to processing machines and equipment (NDEC Title 129 Chapter 4)
Dust generation during construction activities (NDEC Title 129 Chapter 17)
Disposal or decontamination of equipment, structures, etc. (40 CFR 264.114)
On-site health and safety for personnel during remedial actions (29 CFR 1910)
Closure and Post-Closure
Clean Closure (40 CFR 264.111)
Closure with Waste in Place (40 CFR 264.228)
Post-Closure Care (40 CFR 264.117)
Disposal of Soil
Hazardous Waste Determination (40 CFR 261)
Standards for generators (40 CFR 262)
Standards for transporters (40 CFR 263, NDEC Title 128, Ch 3 and Ch 17), and 49 CFR 171
LDRS and Treatment Standards (40 CFR 268)
Location-Specific ARARs
Presence of those species listed in the Endangered Species Act (16 USC 1351 et seq.), the Fish and Wildlife Coordination Act
(16 USC 661 et seq.), 40 CFR 6.302(h), 50 CFR 402, CWA 402, CWA 404, and 40 CFR 231.10(b), and RSN 37-430 to -438 as
being rare, threatened or endangered.
Within an area affecting a stream or river and presence of fish or wildlife resources as defined in the Fish and Wildlife
Coordination Act (16 USC 661 et seq), and 40 CFR 6.302(g).
Location encompassing an aquatic ecosystem with dependent fish, wildlife, other aquatic life or habitat in the Clean Water
Act 404, 40 CFR 230, and 33 CFR 320-330.
Presence of farmlands as defined under 7 CFR 658.4 and 658.5 and the Farmland Protection Policy Act (7 USC 4201 et seq.)
Chemical-Specific TBC Guidance
RDX: 52 µg/g calculated risk-based cleanup level

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 Section 8.0
Sanitary Landfill
Table 8-3. Cost Estimate for Alternative 3
Remedial Action

Units

No.

Unit Price

Cost

Capital
Work Plan

Report

1

$ 17,250.00

$ 17,250.00

Pre-Construction Meeting

Meeting

1

$ 6,960.00

$ 6,960.00

Site Mobilization/Setup

Site

1

$ 8,000.00

$ 8,000.00

Contaminated Soil Removal (Excavation)

Site

1

$ 800.00

$ 800.00

Waste Characterization

Site

1

$ 7,753.00

$ 7,753.00

Soil Transportation

Ton

13

$ 515.00

$ 6,437.50

IDW

55-Gal Drum

2

$130.00

$ 260.00

Disposal Arrangements

Site

1

$ 677.00

$ 677.00

Confirmation Samples for RDX

Sample

2

$ 250.00

$ 500.00

Immunoassay (RDX)

Sample

10

$ 18.00

$ 18.00

Labor

Day

1

$ 650.00

$ 650.00

Backfilling With Clean Soil

CY

4.8

$ 15.00

$ 72.00

Top Soil

CY

4.8

$ 30.00

$ 144.00

Grading and Seeding

SY

25

$ 2.00

$ 50.00

Demobilization

Site

1

$ 5,000.00

$ 5,000.00

Closure Report

Report

1

$ 9,125.00

$ 9,125.00

Deed Restriction

Each

1

$ 5,000.00

$ 5,000.00

Subtotal

$ 71,419.00

$ 10,000.00

$ 10,000.00

Waste Disposal And Transportation

Post Excavation Sampling

Site Restoration

O&M Cost
5-Year Site Review 30-Year Period)

Each

1

Present Worth 5-Year Site Reviews (30-Year Period @ 5%)

$ 28,000.00
Subtotal O&M Cost

$ 28,000.00

Subtotal Cost of Alternative

$ 99,419.00

Contingency (@ 25%)

$ 24,855.00

Project Management (@ 8%)

$ 7,954.00

Total Cost of Alternative

8.6

$ 132,228.00

EXPLANATION OF SIGNIFICANT CHANGES

The Proposed Plan presents the selected remedy as the preferred alternative. No significant changes
have been made.

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 9.0
9.1

SHOP AREA
OPERATIONAL HISTORY

CHAAP contractors, for a variety of base-support functions, have historically used the Shop Area.
Buildings in this area include former maintenance shops where vehicles and equipment were repaired and
serviced; storage areas for chemicals including petroleum products, paints, anti-freeze and solvents; a railroad
car servicing center; and a laundry facility used for cleaning employee garments.
The laundry generated the majority of wastewaters at the Shop Area during periods of ammunition
production. According to aerial photographs, leach fields were apparently used in the 1950s for containing and
possibly treating wastewaters. An area of ground scarring north of Building SSPS-1, as shown in a 1957 aerial
photograph, corresponds to the location of the Shop Area sanitary leachfield (EPIC, 1982). A sanitary
engineering survey conducted in 1970 at CHAAP by the U.S. Army Environmental Hygiene Agency (USAEHA)
(1970) noted that a small quantity of industrial wastewaters from various sources in the Shop Area were
processed through the laundry settling basin.
Major areas of environmental concern have been investigated at the Shop Area. These areas include the
following: the North Ditch; the Paint Shop; the Paint Spray Shop and Pesticide Mixing Building; the Laundry
Settling Basin; the West Ditch; the South Ditch Area; the Former Paint Storage Shed Location; the Sanitary
Leachfield Area; and USTs and ASTs. The following sections summarize historical site activities, observations
from past site inspections, and current conditions.
Buildings in the Shop Area are currently being leased to various industrial clients and are being used
for storage purposes and as office space.
9.2

FINDINGS OF THE REMEDIAL INVESTIGATION

The sampling program at the Shop Area was as follows: geophysical surveying and surface soil sampling
during the 1991 EA; geophysical surveying, surface soil sampling, subsurface soil sampling, groundwater
sampling, and sediment sampling for the 1993 SCD; and geophysical surveying, surface soil sampling,
subsurface soil sampling, and groundwater sampling for the 1995 Rl.
Exhibit 9-1 shows previous soil sampling locations at the Shop Area and locations where lead
concentrations exceeded NDEQ TBC guidance. Exhibit 9-2 shows locations where groundwater COPCs
exceeded the non-residential cleanup levels during sampling rounds conducted in 1995, 1996, and 1998.
9.2.1 Groundwater Sampling Results
AST Area: Sampling results from AST monitoring wells indicate that groundwater has been impacted
by chlorinated solvents. Five ASTs and five USTs were used at the Shop Area, but have been removed.
Tank capacity and contents were compiled from the Mason & Hanger Tank Inventory Reports (Mason
& Hanger, 1982 and 1988). Tank S-6 was a 1,000-gallon AST located at the East End of Building S-6
(garage). The 1982 tank inventory listed the contents as used oil. Tanks S-32, S-34, and S-35 were
located on the east side of the Shop Area. Tank S-32 had a capacity of 10,000-gallons. Tanks S-34 and
S-35 each had a capacity of 12,000 gallons. According to the 1988 tank inventory, all three tanks had
been used for road oil. Tank S-12, the largest tank at CHAAP, was a 577,500-gallon AST located in the
northeast portion of the Shop Area. A 5-ft high secondary containment berm surrounded the tank. The
1988 tank inventory lists the contents as #2 diesel fuel. Provided below are the sampling events that
provided characterization of the chlorinated VOCs in groundwater.
•

1995 Sampling Effort: Chlorinated compounds 1,2-DCA (8.3 µg/L) and 1,1,2-TCA (45 µg/L) were
detected in samples collected during the 1995 field effort from monitoring well SHGWO3. Samples
from monitoring well SHWG02 had a detection of 1,1,2-TCA at 56 µg/L. Each of these detections
exceeds their respective Federal MCLs.

•

1996 Sampling Effort: The 1996 RI follow-on sampling effort was designated to identify the source
areas for the 1,1,2-TCA and 1,2-DCA contamination detected during 1995 field effort in monitoring
wells SHGW02, SHGW03, and SHGW04, as well as to characterize the horizontal and vertical
extent of contamination. Chlorinated solvent 1,1,2-TCA was detected

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Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



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Section 9.0
Shop Area

in Geoprobe TM groundwater screening point SHGP05, which is located immediately downgradient
of AST S-32 at 6.6 µg/L. The detection is far below the concentration of 45 µg/L detected in 1995;
however, it still exceeds the Federal MCL (5 µg/L). 1,2-DCA (12 µg/L) was detected in Geoprobe
TM
point SHGP15, which is located between monitoring well SHGW03 and the AST S-12 berm.
This detection exceeds the Federal MCL (5 µg/L).
•

1998 Groundwater Sampling Results: During the 1998 groundwater sampling event, five monitoring
wells and ten GeoprobeTM points were sampled for chlorinated solvents. Concentrations exceeding
the Federal MCLs were found in the following wells and Geoprobe TM sample points: SHGW02
(1,1,2-TCA 47.8 µg/L), SHGW03 (1,1,2-TCA 32.7 µg/L and 1,2-DCA 7.09), GP02 (1,1,2-TCA 14.8
µg/L), and GP07 (1,2-DCA 5.14 µg/L). Exhibit 9-2 presents the detections of chlorinated solvents
during the 1998 sampling round in groundwater. (It should be noted that detections above Federal
MCLs are denoted in bold on this exhibit.)

Conclusion: The chlorinated VOC plume is apparently decreasing in concentration based on results
of analytical data from 1995, 1996, and 1998 sampling rounds (USACE, 1998b). Natural attenuation
via anaerobic biodegradation rather than hydrodynamic dispersion appears to be responsible for the
decreasing concentrations. The maximum concentrations of 1,1,2-TCA detected was 56.0 µg/L in 1995
in well SHGW02. In 1998, results show a 15% decrease in 1,1,2-TCA. A similar trend can be seen for
1,2-DCA. Further evidence of breakdown is indicated by the detection of vinyl chloride in two locations;
however, it should be noted both concentrations were well below the Federal MCL. The results of the
1996 sampling round indicate that the concentrations of 112- TCA and 1,2-DCA are slightly higher than
Federal MCLs. Data from the 1998 sampling round indicate that natural attenuation processes continue
to be operative at the Shop Area. This is evidenced by a continued decrease in concentrations of
1,1,2-TCA and 1,2-DCA, which for the most part fall below Federal MCLs. Vinyl chloride was detected
only once in 1996, where as in 1998 it was detected in two different sampling locations. This provides
further evidence that breakdown of 1,1,2-TCA and PCE has occurred between the 1996 and 1998
sampling rounds. Hydrogenolysis of 1,1,2-TCA appears to be the primary biodegradation pathway
(evidenced by the detections of 1,2-DCA). However, subsequent breakdown of 1,2-DCA to chloroethane
cannot be confirmed because it was not part of the target analyte list for the 1996 or the 1998 sampling
rounds.
The results of the 1998 sampling round support the proposed preferred alternative of long-term
monitoring of VOCs and their breakdown products in groundwater. The results of 1998 sampling event
further support the conclusions predicted by the numerical fate and transport model performed in 1997,
which suggests that cleanup may occur through natural attenuation within fifteen years.
9.2.2

Building S-22, Building S-37, and Laundry Settling Basin Sampling Results
Building S-22: Building S-22 is the former Paint Shop. Lead was detected in several samples collected
in the vicinity of Building S-22. Four samples, SHOPSR009 (2,400 µg/g), SHOP-8 (570 µg/g),
SHOPSR008 (990 µg/g), and SHOPSR010 (1,500 µg/g) exceeded the NDEQ TBC guidance for lead
(400 µg/g) (Exhibit 9-1).

9.3

CONTAMINANT FATE AND TRANSPORT

Based on monitoring well and GeoprobeTM Sampling results, it has been determined that groundwater
in the vicinity of the AST area has been contaminated with chlorinated solvents. Concentrations of 1,1,2-TCA
and 1,2-DCA have been detected in samples collected during the 1995, 1996, and 1998 sampling efforts. None
of the soil samples collected in the AST area of the Shop Area contained detections of chlorinated organic
solvents. This data indicates that the unsaturated zone in this area is no longer a source of contamination to
the saturated zone.
In 1995, wells SHGW02, SHGW03 and SHGW04 were installed and sampled. The chlorinated solvent
detections for this sampling event suggest a narrow elongated plume extending to the northeast, in the general
direction of groundwater flow. 1,1,2-TCA was detected at the highest concentration (56 µg/L) at the upgradient
end of the plume (Well SHGW02), and occurs at decreased concentration (45
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Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area

µg/L) about 90 ft downgradient in SHGW03. 1,2-DCA also occurs in Well SHGW03 at a concentration of 8.3
µg/L. At the distal end of the plume (Well SHGW04; roughly 350 ft downgradient from SHGW02) 1,1,2-TCA was
not detected, and the concentration of 1,2-DCA was relatively low (0.68 µg/L). The chlorinated solvent
compound distribution is indicative of breakdown of 1,1,2-TCA to 1,2-DCA.
To further characterize the extent of the chlorinated solvent plume, an additional round of sampling was
performed in the AST area in August 1996. The three wells sampled in 1995 were resampled and 17
GeoprobeTM groundwater samples were collected. There were no detections of chlorinated solvents upgradient
(SHGP02 and SHGP04) or downgradient (SHGP09 through SHGP12) of the solvent plume encountered during
the 1995 sampling round, indicating that the plume is apparently immobile, and limited to roughly a 100 ft by
350 ft area. There were no detections of 1,1,2-TCA or 1,2-DCA in 1996 in any of the three wells sampled in
1995. However, 1,1,2-TCA was detected in two of the GeoprobeTM points proximal to SHGW02 (in SHGP05 at
6.6 µg/L; in SHGP06 at 5.0 µg/L). 1,2-DCA (12 µg/L) and vinyl chloride (10.0 µg/L) were detected in the shallow
GeoprobeTM groundwater sample SHGP08 (about 120 ft downgradient from GeoprobeTM point SHGP05). The
only chlorinated solvents detected at the distal end of the plume in 1996 were far below Federal MCLs. The
results of the 1996 groundwater sampling round show a significant reduction in the concentration of 1,1,2-TCA
and provide further evidence of the breakdown of 1,1,2-TCA to 1,2-DCA. The breakdown of 1,2-DCA occurs
either by hydrogenolysis to chloroethane or vinyl chloride. 1,1,2-TCA can also breakdown to vinyl chloride via
dehalogenation. Vinyl chloride was detected in one GeoprobeTM sample in 1996; however, it was detected in
SHGW03 and in GeoprobeTM sample in 1998. Furthermore, 1,2-DCA was also detected in these samples which
suggests that natural attenuation via hydrogenolysis or dehalogenation is occurring.
9.4

REMEDIAL ALTERNATIVES

The findings of the 1996 RI triggered the requirement for an alternatives analysis for lead contamination
in soil in the vicinity of Building S-22 and for chlorinated VOCs in groundwater in the vicinity of the AST area.
The Alternatives Analysis was prepared as part of the 1998 FS (USACE, 1998a).
The purpose of this detailed evaluation of alternatives is to provide performance and cost data that can
be utilized to evaluate further remedial action at the Shop Area. The remedial alternatives are being evaluated
as a means of reducing human health risks to within the range of acceptable risks.
9.4.1

Alternative 1: No Action
Description: According to the NCP, the level of treatment achieved must be compared to the required
expenditures of time and materials as an integral portion of the remedy selection process. The "No
Action" alternative is intended to serve as a baseline by which to compare the risk reduction
effectiveness of other potential alternatives.
Overall Protection of Human Health and the Environment: The "No Action" alternative does not
decrease the potential risks to humans or the environment in any way, because no remedial activities
will be implemented at the site under this alternative. Ingestion or dermal exposure to lead
contamination in surface soil are potential exposure pathways for workers at the site. Groundwater is
unlikely to reach potential off-site receptors. However, the "No Action" alternative does not include a
monitoring system to determine if further remedial action is necessary.
Compliance with ARARs: This alternative does not comply with chemical-specific TBC guidance for
lead as the concentration of lead is above the cleanup level protective of industrial workers. This
alternative also does not comply with chemical-specific ARARs regarding COPCs detected in
groundwater. Chlorinated compounds 1,1,2-TCA and 1,2-DCA are present in concentrations that
exceed the Federal MCLs. Location-specific and action-specific ARARs are not considered because
no remedial activities will be implemented at the site.
Long-term Effectiveness and Permanence: In the long-term, this alternative will not be effective. No
actions will be taken to provide permanent human health and environmental protection.
Reduction of Toxicity, Mobility, or Volume Through Treatment: There will be no further remedial
activities implemented at the site; subsequently, there will be no further reduction of toxicity, mobility,
or volume through treatment.

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Final Document

 Section 9.0
Shop Area

Short-term Effectiveness: Short-term effectiveness does not apply to the "No Action" alternative
because no additional remedial activities will be implemented at the site.
Implementability: There are no implementability concerns associated with the "No Action" alternative
because no remediation activities will be conducted at the site.
Cost: There are no capital costs associated with this alternative. However, an evaluation report will be
submitted every five years for a 30-year period at a total present worth cost of $37,240.
9.4.2

Alternative 2: Soil Excavation, Long-term Monitoring for Natural Attenuation of Chlorinated
Organic Compounds in Groundwater, and Deed Restriction
Description: This alternative consists of monitoring the natural attenuation of an identified chlorinated
volatile organic compound (VOC) plume at the Shop Area and excavation and off-site disposal of
lead-contaminated soil (see Exhibit 9-3).
•

Excavation of Lead-Contaminated Soil: Lead-contaminated soil at the North Ditch Area would be
removed to the NDEQ cleanup level. An area of approximately 50 ft by 10 ft to a depth of one foot
would be excavated (the volume is approximately 18.5 yd3). The excavation effort could be
completed with conventional construction equipment (e.g., wheeled front-end loader) in one day.
Upon completion of the soil excavation, lead screening using XRF would be used to determine if
excavation of soil to the cleanup level has been completed. If screening data indicates that removal
of lead to the cleanup level has been accomplished, five samples would be collected for
confirmational analysis. The excavated soil would be placed in two 20-ton capacity roll-offs. Prior
to the excavation, two samples would be collected and tested to determine if the soil is a
RCRA-hazardous waste. If the soil fails the Toxicity Characteristic Leaching Procedure (TCLP) for
lead, the soil is considered a hazardous waste and would be disposed of RCRA Subtitle C Landfill
that can accept wastes from a CERCLA site. The excavated area would be backfilled with clean
soil (approximately 21.3 yd 3 ) and reseeded.

•

Monitoring for Natural Attenuation of the Chlorinated VOC Plume: Alternative Two would involve the
monitoring of groundwater upgradient and downgradient of the Shop Area chlorinated VOC plume
as well as the removal and off-site disposal of lead contaminated soil from the North Ditch Area,
northeast of Building S-22. The monitoring well locations and area of soil excavation are displayed
in Exhibit 9-3. Groundwater upgradient and downgradient would be screened for the TCL VOC List
(chlorinated organics), dissolved oxygen, redox potential, and ethane/ethene. Samples from four
wells will be collected and analyzed on an annual basis.

•

This alternative also includes implementation of deed restrictions to prevent residential use. The
deed restrictions will include proprietary institutional controls restricting the future use of the
property such as easements or restrictive covenants that are legally enforceable against
subsequent property owners and instituted, depending on state law, by conveyance or contract.
The U.S. Army will be responsible for implementing and maintaining the effectiveness of the
institutional controls.

Overall Protection of Human Health and the Environment:
•

Excavation of Lead-Contaminated Soil: The removal of lead contaminated soil to the NDEQ
cleanup level of 400 µg/g is protective of humans under non-residential conditions.

•

Monitoring for Natural Attenuation of Chlorinated VOC Plume: Natural attenuation could be
considered protective of human heath and the environment. Based on future use of the
groundwater, exposure to humans is unlikely. Field sampling analytical results and results of the
BIOF&T-2D fate and transport model suggest that the chlorinated solvent plume is shrinking and,
therefore, will not migrate off-site.

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Cornhusker Army Ammunition Plant
Final Document

  

 

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Section 9.0
Shop Area

Compliance with ARARs:
• Excavation of Lead-Contaminated Soil:
Chemical-specific TBC guidance: The lead-contaminated soil excavation portion of this alternative
would meet the chemical-specific TBC guidance for lead.
Location-specific ARARs: The lead-contaminated soil excavation portion of this alternative is not
expected to affect any location-specific ARARs.
Action-specific ARARs: The proposed remedial design and operation should meet action-specific
ARARs.
• Monitoring for Natural Attenuation of the Chlorinated VOC Plume:
Chemical-specific ARARs: The Federal MCLs for 1,1,2-TCA and 1,2-DCA are likely to be met by this
alternative.
Location-specific ARARs: Location-specific ARARs would not be affected by this alternative.
Action-specific ARARs: Action-specific ARARs are not considered because no remedial activities
will be implemented at the site for addressing groundwater.
Long-term Effectiveness and Permanence:
• Excavation of Lead Contaminated Soil: In the long-term, the lead-contaminated soil excavation
portion of this alternative would be effective because the lead would be removed to a level that is
below the cleanup level protective of industrial workers.
• Monitoring for Natural Attenuation of the Chlorinated VOC Plume: Natural attenuation may be
occurring in groundwater. This will be determined by long-term monitoring.
Reduction of Toxicity, Mobility, or Volume Through Treatment:
• Excavation of Lead-Contaminated Soil: Volume will be reduced since the lead-contaminated soil will
be removed and disposed at a off-site disposal facility. Toxicity and mobility will not be reduced since
no treatment is involved.
• Monitoring for Natural Attenuation of the Chlorinated VOC Plume: For groundwater, toxicity, mobility
and volume may be reduced through the natural attenuation process.
Short-term Effectiveness:
• Excavation of Lead-Contaminated Soil: This alternative poses minimal risk to the community,
workers, and the environment during its implementation. The remote location on a military facility
would minimize unauthorized public access to the site. Workers involved with the excavation
activities could be exposed to risks including dermal contact with contaminated soil and breathing
contaminant dust and vapors. The emission levels, however, will be low, and workers will be
protected by use of appropriate personal protective equipment. No protected species are to be
affected during remediation.
• Monitoring for Natural Attenuation of the Chlorinated VOC Plume: Because no remediation is
involved, no risk to the human health and the environment is expected.
Implementability
• Excavation of Lead-Contaminated Soil: Equipment and materials for implementing this alternative are
readily available. If selected as the remedial action, excavation could be implemented in less than
six months.
• Monitoring for Natural Attenuation of the Chlorinated VOC Plume: The only actions necessary for
implementing this alternative are installation of a monitoring well and the performance of sampling
and laboratory analyses. Equipment and services for performing these actions are readily available.
Installation of the proposed monitoring well could be implemented in less than one month. Based on
the BIOF&T-2D model, 1,1,2-TCA and 1,2DAAA15-91-D-0014
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October 1999

9-8

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area

DCA should reduce to concentrations below their respective Federal MCLs in 15 years (CHAAP OU3
and OU4 FS - Appendix E).
Cost: The estimated capital cost and annual O&M costs are $48,621 and $108,250, respectively. The
net present worth of costs for 30 years at 5% interest for this alternative is estimated to be $232,169.
9.4.3

Alternative 3: Soil Excavation, Liquid-Phase Carbon Adsorption, and Deed Restriction
Description: This alternative includes treating the groundwater with granular activated carbon (GAC) and
performing semi-annual monitoring. This alternative also includes the excavation and disposal of
lead-contaminated soil as described in Alternative Two.
GAC treatment is a physical process that uses GAC to remove a wide variety of contaminants by
adsorbing them from liquid. It was estimated that the system would need to be operated for no more
than 10 years to reduce VOC concentrations to Federal MCLs (see CHAAP OU3 and OU4 FS Appendix E).
A capture zone analysis for the pump and treat alternative was performed using the numerical model
FLOWPATH (refer to CHAAP OU3 and OU4 FS - Appendix E). Results of the model suggest that a
30-gallon per minute (gpm) extraction rate will be sufficient to capture the chlorinated solvent plume.
The liquid phase GAC system proposed for the Shop Area is a 30-gpm liquid system utilizing six
10-gpm-carbon canisters connected in series and parallel. One 4-inch diameter extraction well with a
30-gpm, 1.5 Hp submersible pump would be used to extract the groundwater into the carbon adsorption
unit. Based on vendor estimates, for every 1,000 gallons of water, approximately 0.69 pounds of GAC
would be used in removing 1,1,2-TCA and 1,2-DCA to below their respective Federal MCLs. It is
estimated that three canisters would have to be exchanged every 21 days. Filters would be used before
the system to remove iron and manganese from the water to prevent clogging of the GAC units. Based
on conversations with vendors, the filters would need to be changed every month.
The proposed discharge location is the railroad ditch, which is also used as the discharge location for
the OU1 groundwater treatment system. The piping used would be 2-inch diameter polyvinyl chloride,
(PVC) pipe. The piping (to be encased in a dual pipe casing) would be laid underneath of the railroad
track to be discharged directly to the railroad ditch. A National Pollutant Discharge Elimination System
(NPDES) permit will be required. It should be noted that no off-gas treatment system will be required
because of the low concentrations present in groundwater. This alternative proposes the annual
monitoring of the chlorinated organic compound plume. In addition, influent and effluent to the Carbon
adsorption system would be monitored on a daily basis for Target Compound List (TCL) VOCs
(chlorinated organics only).
This alternative also includes implementation of deed restrictions to prevent residential use. The deed
restrictions will include proprietary institutional controls restricting the future use of the property such
as easements or restrictive covenants that are legally enforceable against subsequent property owners
and instituted, depending on state law, by conveyance or contract. The U.S. Army will be responsible
for implementing and maintaining the effectiveness of the institutional controls.
Overall Protection of Human Health and the Environment: This alternative will reduce the concentrations
of 1,1,2-TCA and 1,2-DCA to below Federal MCLs and, therefore, would provide protection to human
health and environment.
Compliance with ARARS:
Chemical-specific ARARs: The Federal MCLs for 1,1,2-TCA and 1,2-DCA are to be met by this
alternative.
Location-specific ARARs: Location-specific ARARs would not be affected by this alternative.

DAAA15-91-D-0014
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October 1999

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Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area

Action-specific ARARs: ARARs that must be addressed in evaluating the GAC process and off-site
disposal of spent carbon. The proposed remedial design and operation would meet all
action-specific ARAR requirements.
Long-term Effectiveness and Permanence: Implementation of this alternative will essentially eliminate
the long-term risk associated with VOC-contaminated groundwater. No long-term residual risk will be
associated with the treated groundwater by the liquid-phase carbon adsorption system. The need for
replacement of mechanical components, such as extraction pumps, will be minimal through execution
of proper maintenance activities.
Reduction of Toxicity, Mobility, or Volume Through Treatment: The GAC system will effectively reduce
the mobility and volume of the contaminants in the extracted groundwater. Toxicity will not be reduced,
but contaminants will be concentrated in the GAC. The spent carbon generated from the carbon
adsorption unit will be shipped to the carbon supplier for off-site regeneration. The adsorbed organics
will be thermally decomposed to non-toxic compounds (such as carbon dioxide) during the
regeneration process.
Short-term Effectiveness: Community risk associated with implementation of this alternative will be low
because the spent carbon will be shipped off-site for regeneration. Environmental impacts resulting from
installation and operation of this alternative will be minimal.
Implementability: Installation of the groundwater extraction system and construction of the treatment
facility are relatively simple and established procedures. The use of the carbon adsorption unit to
remove organic contaminants in groundwater is proven and reliable. All the technologies required to
implement this alternative will be readily available. Administrative efforts in obtaining Federal and State
permits will be required for the discharge of treated water to the railroad ditch. The design, construction,
and operation of this system could be implemented in one year. Based on computer modeling, the
length of time required for 1,1,2-TCA and 1,2-DCA to meet Federal MCLs is 10 years (see CHAAP OU3
and OU4 FS - Appendix E).
Cost: The estimated capital cost and annual O&M costs are estimated to be $353,000 and $432,000,
respectively. The net present worth of costs for 10 years at 5% interest for this alternative is estimated
to be $3.7 Million.
9.4.4

Alternative 4: Soil Excavation, Air Stripping, and Deed Restriction
Description: This alternative includes treating the groundwater by extracting and pumping it through a
stacked tray air stripper and performing semi-annual monitoring of groundwater. This alternative also
includes the excavation and disposal of lead-contaminated soil as described in Alternative Two.
Air stripping involves the mass transfer of volatile contaminants from water to air. This process is
conducted in a packed tower. The typical packed tower air stripper includes a spray nozzle at the top
of the tower to distribute contaminated water over the packing in the column, a fan to force air
countercurrent to the water flow, and a sump at the bottom of the tower to collect decontaminated
water. This water will be discharged into the railroad ditch, upon obtaining the necessary NPDES
permit. Based on calculations presented in the FS, it was determined that the system will need to be
in operation for no more than 10 years to reduce contaminant concentrations to below Federal MCLs.
A capture zone analysis for the pump and treat alternative was performed using the numerical model
FLOWPATH. Results of the model suggest that a 30-gpm extraction rate will be sufficient to capture
the chlorinated solvent plume. A detailed discussion of the FLOWPATH model is presented in CHAAP
OU3 and OU4 FS - Appendix E.
The air stripping system proposed for the Shop Area is a five-tray, gravity-drain configuration model.
One 4-inch diameter extraction well with a 30-gpm, 1/3 Hp submersible pump would be used to extract
the groundwater and pump it into the air stripper. Filters would be used before the system to remove
iron and manganese from the water to prevent clogging of the air stripper. Based on conversations with
vendors, the filters would need to be changed every month.

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October 1999

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Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area

The proposed discharge location is the railroad ditch, which is also used as the discharge location for
the OU1 groundwater treatment system. The piping used would be 2-inch diameter PVC pipe. Effluent
samples would be collected monthly and analyzed for chlorinated VOCs. A 30,000 gallon effluent tank
would be installed for use in case of an emergency. A 30-gpm, 1/3 Hp pump would be used to move
the treated water from the holding tanks to the railroad drainage ditch. A NPDES permit will be
required. It should be noted that no off-gas treatment system will be required because of the low
concentrations of VOCs present in groundwater.
This alternative proposes the annual monitoring of the chlorinated organic compound plume. In addition,
influent and effluent to the carbon adsorption system would be monitored on a daily basis for TCL
VOCs (chlorinated organics only).
This alternative also includes implementation of deed restrictions to prevent residential use. The deed
restrictions will include proprietary institutional controls restricting the future use of the property such
as easements or restrictive covenants that are legally enforceable against subsequent property owners
and instituted, depending on state law, by conveyance or contract. The U.S. Army will be responsible
for implementing and maintaining the effectiveness of the institutional controls.
Overall Protection of Human Health and the Environment: This alternative will reduce the concentrations
of 1,1,2-TCA and 1,2-DCA to below Federal MCLs and, therefore, would provide protection to human
health and environment.
Compliance with ARARs:
Chemical-specific ARARs: The Federal MCLs for 1,1,2-TCA and 1,2-DCA are to be met by this
alternative.
Location-specific ARARs: Location-specific ARARs would not be affected by this alternative.
Action-specific ARARs: The proposed remedial design and operation should meet all Actionspecific ARAR requirements.
Long-term Effectiveness and Permanence: Implementation of this alternative will essentially eliminate
the long-term risk associated with VOC-contaminated groundwater. No long-term residual risk will be
associated with the groundwater treated by the air stripping system. The need for replacement of
mechanical components, such as extraction pumps, will be minimal through execution of proper
maintenance activities.
Reduction of Toxicity, Mobility, or Volume Through Treatment: The air stripping system will effectively
reduce the mobility and volume of the contaminants in the extracted groundwater. Toxicity will not be
reduced, but contaminants will be removed from the groundwater in a vapor-phase form.
Short-term Effectiveness: Community risk associated with implementation of this alternative will be low
because the amount of vapor emissions from this system will be far below Nebraska air pollution
control regulations. Environmental impacts resulting from installation and operation of this alternative
will be minimal.
Implementability: Installation of the groundwater extraction system and construction of the treatment
facility are relatively simple, established procedures. The use of the air stripping unit to remove organic
contaminants in groundwater is proven and reliable. All the technologies required to implement this
alternative will be readily available. Administrative efforts in obtaining Federal and State permits will be
required for the discharge of treated water to the railroad ditch. The design, construction, and operation
of this system could be implemented in six months. Based on calculations, the length of time required
for 1,1,2-TCA and 1,2-DCA to meet Federal MCLs is 10 years (refer to CHAAP OU3 and OU4 FS Appendix E).
Cost: The present worth cost at five percent interest is approximately $2.8 Million. The capital and
O&M costs are to be $362,000 and $323,000, respectively.

DAAA15-91-D-0014
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October 1999

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Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area

9.5

SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES FOR THE SHOP AREA

As required by CERCLA, the remedial alternatives described above were evaluated using nine criteria
specified by USEPA. Table 9-1 summarizes a comparative analysis of the four remedial alternatives presented
in the CHAAP OU3 and OU4 FS.
Table 9-1. Comparative Analysis of Remedial Action Alternatives –Shop Area
NCP
Criteria

Alternative 1
No Action

Alternative 2
Soil Excavation,
Monitoring and
Natural Attenuation
of Groundwater,
and
Deed Restriction

Alternative 3
Soil Excavation,
Liquid-Phase Carbon
Adsorption, and Deed
Restriction

Alternative 4
Soil Excavation, Air
Stripping, and Deed
Restriction

All contamination
above levels causing
risk would be
removed

See Alternative 2.

See Alternative 2.

1. OVERALL PROTECTIVENESS
Direct Contact/Soil
Ingestion

No significant
reduction in risk.
Contaminant levels
remain in soil.

2. COMPLIANCE WITH ARARS/TBC GUIDANCE
Chemical-Specific
ARARs

Chemical-Specific
ARARs and TBC
guidance would not
be met.

Would meet all
chemical-specific
ARARs.

See Alternative 2.

See Alternative 2.

Location-Specific
ARARs

There are no locationspecific ARARs.

Would meet all
location-specific
ARARs

See Alternative 2.

See Alternative 2.

Action-Specific
ARARs

There are no actionspecific ARARs.

Would meet all
action-specific
ARARs

See Alternative 2.

See Alternative 2.

TBC Guidance for
Lead

Does not meet
protection of industrial
worker cleanup levels.

Would meet TBC
guidance.

See Alternative 2.

See Alternative 2.

3. LONG-TERM EFFECTIVENESS AND PERMANENCE
Magnitude of
Residual Risk (Direct
Contact/Soil
Ingestion)

Source has not been
removed. Existing risk
will remain.

Risk is eliminated
since source is
removed.

Risk is minimized since
source is removed.

Risk is minimized since
source is removed.

Adequacy and
Reliability of Controls

No controls over
remaining
contamination. No
reliability.

Reliability of soil
removal high, since
all contaminants
above remedial
goals will be
removed from the
site. Data analysis
and modeling
indicate that natural
attenuation is
occurring at this site.

Reliability of soil
removal high, since all
contaminants above
remedial goals will be
removed from the site.
Carbon adsorption is
an effective
technology for
remediating VOCs in
groundwater.

Reliability of soil
removal high, since all
contaminants above
remedial goals will be
removed from the site.
Air stripping is an
effective technology
for remediating VOCs
in groundwater.

Need for 5-Year
Review

Review would be
required.

A 5-year review will
be required until
groundwater
cleanup objectives
are reached. A
closure report will be
prepared when
cleanup objectives
are reached. 5-year
reviews will also be
conducted as part of
the Deed
Restrictions.

See Alternative 2.

See Alternative 2.

DAAA15-91-D-0014
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October 1999

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Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area
Table 9-1. Comparative Analysis of Remedial Action Alternatives – Shop Area
Alternative 1
Alternative 2
Alternative 3
No Action
Soil Excavation,
Soil Excavation,
Monitoring and
Liquid-Phase Carbon
Natural Attenuation
Adsorption, and Deed
of Groundwater, and
Restriction
Deed Restriction
4. REDUCTION IN TOXICITY, MOBILITY, AND VOLUME THROUGH TREATMENT
Treatment Process
None.
Excavation and off-site
Excavation and off-site
Used
disposal for soil.
disposal for soil. Carbon
adsorption is used to
separate contaminants
from groundwater.
NCP
Criteria

Amount Destroyed
or Treated

None.

Reduction of
Toxicity, Mobility,
or Volume

None.

Irreversible
Treatment

None.

Type and Quantity
No residuals remain.
of Residuals
Remaining after
Treatment
Statutory
Does not satisfy.
Preference for
Treatment
5. SHORT-TERM EFFECTIVENESS
Community
Risk to community not
Protection
increased by remedy
implementation, and
contamination not
expected to reach
community in future.
Worker Protection
No significant risk to
workers.

Environmental
Impacts
Time until Action is
Complete
6. IMPLEMENTABILITY
Ability to Obtain
Approvals and
Coordinate with
other Agencies
Availability of
Services and
Capacities

DAAA15-91-D-0014
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October 1999

Continued impact from
existing conditions.
Not applicable.

No approval necessary.

No services or
capacities necessary.

Soil: 18.5 yd 3
Groundwater:
864,000 gallons
In soil, no reduction in
toxicity or mobility, but
volume of
contaminated soil is
reduced. TMV is
reduced for
groundwater through
the natural attenuation
process.

See Alternative 2.

Alternative 4
Soil Excavation, Air
Stripping, and Deed
Restriction

Excavation and offsite disposal for soil.
Air stripping is used
to separate
contaminants from
groundwater.
See Alternative 2.

In soil, no reduction in
toxicity or mobility, but
volume of contaminated
soil is reduced. Mobility
and volume in
groundwater are
reduced because
chlorinated VOCs are
removed to levels lower
than Federal MCLs.
Toxicity is not reduced
because no treatment is
used.
None.

See Alternative 2.

Spent carbon will be
returned to vendor for
treatment.

None.

Satisfies.

Satisfies.

Satisfies.

Temporary increase in
dust production during
excavation.

Temporary increase in
dust production during
excavation and remedy
implementation.

See Alternative 3.

Protection required
against dermal contact
of contaminants and
inhalation of
contaminated dust
during excavation and
monitoring activities.

Protection required
against dermal contact
of contaminants and
inhalation of
contaminated dust
during excavation
monitoring, and system
implementation
activities.
See Alternative 2.

See Alternative 3.

The natural
attentuation process is
irreversible.
No detectable
residuals remain
above cleanup levels.

No environmental
impacts from remedial
action.
15 years based on
remodeling.
Program for natural
attenuation will
require approval from
regulators.
Service and Capacities
readily available.

9-13

None.

See Alternative 2.

10 years, based on
modeling.

See Alternative 3.

Must obtain a NPDES
permit for groundwater
discharge.

Must obtain a
NPDES permit for
groundwater
discharge.
See Alternative 2.

See Alternative 2.

Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area
Table 9-1. Comparative Analysis of Remedial Action Alternatives – Shop Area
NCP
Criteria

Alternative 1
No Action

Alternative 2
Soil Excavation,
Monitoring and
Natural Attenuation of
Groundwater, and
Deed Restriction

Alternative 3
Soil Excavation,
Liquid-Phase Carbon
Adsorption, and Deed
Restriction

Alternative 4
Soil Excavation, Air
Stripping, and Deed
Restriction

Availability of
Equipment,
Specialists, and
Materials

None required.

Equipment, specialists,
and material readily
available.

See Alternative 2.

See Alternative 2.

Availability of
Technologies.

None required.

Readily available.

See Alternative 2.

See Alternative 2.

Capital Cost

$0

$48,621

$353,000

$362,000

O&M Cost

$28,000

$108,250

$432,000

$323,000

$37,240

$232,169

$3.7 Million

$2.8 Million

7. Cost

Present Worth Cost

1

1

- 15 year present worth used for Alternative Two, 10-year present worth used for Alternatives Three and Four. Costs
of five-year reviews are based on a 30-year period.

9.5.1

Protection of Human Health and Environment

COPCs, lead in soil and chlorinated VOCs (e.g., 1,1,2-TCA and 1,2-DCA) in groundwater, were
detected at concentrations greater than the cleanup level. Alternative One will not meet this criterion because
no actions are taken to eliminate, reduce, or control exposure pathways. Alternative One does not achieve the
threshold criterion of protection of human health and the environment.
Alternative Two provides protection of human health and the environment by eliminating the surface soil
exposure pathway as well as mitigating migration of lead into groundwater (sources are removed). Therefore,
implementation of this alternative would allow future land use for non-residential conditions. Alternative Two is
likely to reduce contaminants in groundwater to below groundwater cleanup levels (i.e., Federal MCLs), but will
take longer to do so than Alternatives Three and Four.
Alternatives Three and Four provide protection of human health under non-residential conditions by
eliminating the surface soil exposure pathway as well as mitigating migration of lead into groundwater (sources
are removed). Therefore, implementation of these alternatives would allow future non-residential land use of the
Shop Area. Alternatives Three and Four reduce contaminants in groundwater to below Federal MCLs, thereby,
allowing unrestricted use of groundwater.
9.5.2

Compliance with ARARs

Compliance with ARARs is a threshold criterion that must be met by the proposed remedial action.
Alternative One does not meet the chemical-specific TBC guidance because lead remains in soil. Alternatives
Two, Three, and Four involve further actions to eliminate exposure to contaminated soil and mitigate migration
of lead into groundwater. These alternatives also reduce VOCs in groundwater to levels that meet
chemical-specific ARARs.
9.5.3

Long-term Effectiveness and Permanence

Alternative One does not provide long-term effectiveness and permanence. This alternative does not
provide sufficient, effective protection of groundwater and potential exposure to humans from exposure to
contaminated soils and groundwater. Alternatives Two, Three, and Four provide long-term prevention of
exposures to lead-contaminated surface soil and migration of lead from soils into groundwater because sources
are removed. Alternatives Two, Three, and Four will provide long-term protection and permanence. However,
Alternative Two will take longer to achieve permanence.
Reviews at least every five years, as required, would be necessary to evaluate the effectiveness of any
of these alternatives because hazardous substances would remain onsite in concentrations above health-based
levels.
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Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area

9.5.4

Reduction of Toxicity, Mobility or Volume through Treatment

Alternative One does not provide reduction of toxicity, mobility, or volume of the contaminants.
Alternatives Two, Three, and Four provide reduction of volume for soil because all lead is removed to levels lower
than the cleanup level protective of industrial workers. Alternative Two provides reduction of toxicity, mobility,
and volume of contaminants in groundwater because chlorinated VOCs are reduced to levels lower than Federal
MCLs. Alternatives Three and Four provide reduction of mobility and volume because chlorinated VOCs in the
groundwater are removed to levels lower than Federal MCLs. Toxicity is not reduced for Alternatives Three and
Four because no treatment is used.
9.5.5

Short-term Effectiveness

Short-term effectiveness is not applicable to Alternative One. Alternatives Two, Three, and Four require
the use of proper dust suppressant measures to control windblown emissions of potentially contaminated dust
to protect the community and on-site workers. Proper personal protective equipment would be required for site
workers. Workers will take appropriate safety measures to perform their functions (e.g., drilling, sampling,
installation of groundwater treatment alternatives). Measures to protect the environment are not expected for
implementing these alternatives.
Alternative One takes the shortest time to implement because no action is involved. Alternative Two
should be implemented in less than six months because it only involves the installation of a monitoring well and
excavation of soil. Alternatives Three and Four will take one year to implement to allow for design, construction,
and permitting of the pump and treat systems.
9.5.6

Implementability

Alternatives One and Two are the most easily implemented. Alternative One is a no further action
alternative. Alternative Two involves the installation of a monitoring well, sampling, and excavation. Pump and
treat systems proposed in Alternatives Three and Four would also be fairly easy to implement because they
use developed commercial technologies. Alternatives Two, Three, and Four involve excavation and landfilling
of contaminated soils. Excavations to the depths proposed indicate that these alternatives would be easy to
implement. The excavation (approximately 1 ft bgs) would not require shoring or dewatering.
9.5.7

Cost

Total capital and annual costs and present worth (discount rate of 5%) for each alternative are
presented in Table 9-1.
9.6

SELECTED REMEDY

The selected remedy for the Shop Area is Alternative Two – Soil Excavation and Long-term Monitoring
for Natural Attenuation of Groundwater (Exhibit 9-3). Alternative Two is the preferred alternative because it
provides the best balance of features that offer overall protection to human health and the environment; is easy
to implement; it quickly and permanently reduces the toxicity, mobility, and volume of lead-contaminated soil;
it meets all ARARs and TBC guidance; is cost-effective; and involves monitoring of chlorinated organic
compound concentrations in groundwater until they are reduced to below MCLs. Excavation of contaminated
soils will remove risk to human and ecological receptors for the site. In addition, this action is easy to
implement and involves minimal risks to site workers. The deed restrictions will include proprietary institutional
controls such as easements or restrictive covenants that are legally enforceable against subsequent property
owners and instituted, depending on state law, by conveyance or contract. The. U.S. Army will be responsible
for implementing and maintaining the effectiveness of the institutional controls. Table 9-2 presents ARARs and
TBC Guidance for Alternative 2. Table 9-3 provides a detailed cost estimate for Alternative 2.

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Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area

Table 9-2. ARARs and TBC Guidance for Alternative 2
Action-Specific ARARs
Excavation
Regulations to processing machines and equipment (NDEC Title 129 Chapter 4)
Dust generation during construction activities (NDEC Title 129 Chapter 17)
Disposal or decontamination of equipment, structures, etc. (40 CFR 264.114)
On-Site health and safety for personnel during remedial actions (29 CFR 1910)
Closure
Clean Closure (40 CFR 264.111)
Disposal of Soil
Hazardous Waste Determination (40 CFR 261)
Standards for generators (40 CFR 262)
Standards for transporters (40 CFR 263; NDEC Title 128, Ch 3 and Ch 17; and 49 CFR
171)
LDRS and Treatment Standards (40 CFR 6, Appendix A)
Location-Specific ARARs
Executive Order 11988 (Floodplain Management) Evaluate potential effects of actions, avoid
impacts to the extent possible (40 CFR 6, Appendix A)
Presence of wetlands as defined in Executive Order 11990 Section 7(c) 40 CFR 6, Appendix A,
Section 4(j), Clean Water Act 404, and 33 CFR 328.3(b)
Presence of those species listed in the Endangered Species Act (16 USC 1351 et seq), the Fish
and Wildlife coordination Act (16 USC 661 et seq), 40 CFR 6.302(h), 50 CFR 402, CWA 404, and
40 CFR 231.10(b), and RSN 37-430 to -438 as being rare, threatened or endangered.
Presence of farmlands as defined under 7 CFR 658.4 and 658.5 and the Farmland Protection
Policy Act (7 USC 4201 et seq)
Chemical-Specific ARARs/TBC Guidance
Lead: NDEQ Cleanup Level Protective of Non-residential Conditions
TCE and PCE: Federal MCLs

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Final Document

 Section 9.0
Shop Area

Table 9-3. Cost Estimate for Alternative 2
Remedial Action

Units

No.

Unit Price

Cost

Well

1

$2,500.00

$2,500.00

Day

1

$480.00

$480.00

Day

1

$1,350.00

$1,350.00

Lead (Total)

Sample

3

$18.00

$54.00

Full TCLP

Sample

1

$1,412.00

$1,412.00

Capital
Groundwater Monitoring
New Monitoring Wells
Excavation
Excavation (Backhoe, Loader)
Confirmatory Sampling/Analyses
On-site Screening:
XRF Screening (Lead)
Confirmation Sampling:

Transportation for Disposal

Truck

1

$2,300.00

$2,300.00

Off-Site Disposal (Landfill)

Tons

15

$350.00

$5,250.00

CY

15

$15.00

$225.00

Grading and Seeding

SY

25

$2.00

$50.00

5-Year Evaluation Report1

Site

1

$30,000.00

$30,000.00

Each

1

$5,000.00

$5,000.00

Backfill with Clean Soil

Deed Restriction

Subtotal

$48,621.00

Annual O&M Cost
Groundwater Monitoring
Groundwater Analysis

Sample

10

$300.00

Sampling Labor, Preparation and Reporting

Hours

160

$30.00

Present Worth Groundwater Monitoring (15-Year Period @ 5%)

$3,000.00
$4,800.00
$80,250.00

Other O&M Cost
5-Year Site Review (30-Year Period)

Each

1

Present Worth 5-Year Site Reviews (30-Year Period @ 5%)

$10,000.00

$10,000.00
$28,000.00

Subtotal O&M Cost

$108,250.00

Subtotal Cost of Alternative

$156,871.00

Contingency (@ 25%)

$39,218.00

Engineering and Design (@ 15%)

$23,530.00

Project Management (@ 8%)

$12,550.00

Total Cost of Alternative

$232,169.00

1

Need for additional evaluation will be determined after initial 5-year review.

9.7

EXPLANATION OF SIGNIFICANT CHANGES

The Proposed Plan presents the selected remedy as the preferred alternative. No significant changes
have been made.

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Cornhusker Army Ammunition Plant
Final Document

 Section 9.0
Shop Area

RESPONSIVENESS SUMMARY

10.0

The final component of the ROD is the Responsiveness Summary. The purpose of the Responsiveness
Summary is to provide a summary of the public's comments, concerns, and questions about OU3 and the
Army's responses to these concerns. The public comment period extended from April 21, 1999 to May 1, 1999.
The following is a summary of events that have progressed on the public meeting activities for OU3
sites:
•

10.1

CHAAP held a public meeting on April 28, 1999, to formerly present the Proposed Plan and to
answer questions and receive comments. No comments were submitted by the public at the
meeting or during the public comment period (i.e., April 21, 1999 through May 21, 1999).

OVERVIEW

This Record of Decision presents the preferred remedial alternatives to meet the RAOs which are to
protect human health under non-residential conditions, including industrial and agricultural use. Table 10-1
presents the AOCs, corresponding chemicals of concern, affected RAO (numerical standard), and the preferred
remedial alternative. EPA and NDEQ concur with the selected remedies.
Table 10-1. Summary of Preferred Remedial Alternatives for OU3
Area of Concern
Nitrate Area

COPC

Affected Media

RAO

Lead

Soil

400 µg/g
(NDEQ TBC
Guidance)

Preferred Remedial Alternative
Title:

Excavation, Off-Site Disposal of
Lead-Contaminated Soil, and
Deed Restriction to Prevent
Residential Use
$132,176

Cost:
Implementation Time: Less than six
months
Pistol Range

Lead
RDX

Soil

Title:

Lead - 400 µg/g
(NDEQ TBC
Guidance)
RDX - 52 µg/g
(Risk-Based)

Excavation, Off-Site Disposal of
RDX-and Lead-Contaminated
Soil, and Deed Restriction to
Prevent Residential Use
$227,147

Cost:
Implementation Time: Less than six
months
Sanitary Landfill

RDX

Soil

52 µg/g
(Risk-Based)

Title:

Excavation, Off-Site Disposal of
RDX-Contaminated Soil, and
Deed Restriction to Prevent
Residential Use
$132,228

Cost:
Implementation Time: Less than six
months
Shop Area

Soil - Lead
Groundwater 1,1,2,-TCA, 1,2DCA

Soil and
Groundwater

Lead - 400 µg/g
(NDEQ TBC
Guidance)
1,1,2-TCA - 5 µg/L
1,2-DCA - 5 µg/L
(Federal MCL)

Title:

Cost:

Soil Excavation, Long-term
Monitoring for Natural
Attenuation of Groundwater,
and Deed Restriction to Prevent
Residential Use
$232,169

Implementation Time: Soil - less than
six months; Groundwater - 15 years

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Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document

 11.0

REFERENCES

Dragun, J. and Chiasson, A. 1991. Elements in North American Soil. Hazardous Materials Controls Resources
Institute. Greenbelt, MD.
EPIC.

1982. Installation Assessment CHAAP, Nebraska, Report TS-PIC-0066, Prepared for: Commander,
U.S. Army Toxic and Hazardous Materials Agency, Aberdeen Proving Ground, Maryland.

Mason & Hanger-Silas Mason Co., Inc. 1982. Engineering Drawing DA-100-0-101. February 1982.
Mason & Hanger-Silas Mason Co., Inc. 1988. Tabulation of Tanks, Drawing G-100-0-112. December 1988.
Rupp, Dan. 1991. Personal communication.
U.S. Army Corps of Engineers - Omaha District (USACE). 1998a. Cornhusker Army Ammunition Plant
Feasibility Study Report for Operable Unit Three and Operable Unit Four, Final Document. January
1998.
U.S. Army Corps of Engineers - Omaha District (USACE). 1998b. Natural Attenuation Assessment for
Chlorinated Volatile Organic Compounds in Groundwater at the Shop Area, CHAAP Feasibility Study
Addendum for Operable Units Three and Four. Draft Document. September 1998.
U.S. Army Corps of Engineers - Omaha District (USACE). 1999. Cornhusker Army Ammunition Plant Operable
Unit Three and Operable Unit Four Proposed Plan, Final Document. April 1999.
U.S. Army Environmental Center (USAEC). 1996. Cornhusker Army Ammunition Plant Remedial Investigation
Report, Final Document. November 1996.
U.S. Army Environmental Hygiene Agency (USAEHA). 1970. Sanitary Engineering Survey 24-010-71, CHAAP,
Grand Island, Nebraska. December 1970.
U.S. Army Toxic and Hazardous Material Agency (USATHAMA). 1980. Installation Assessment of Cornhusker
Army Ammunition Plant, Report 155. March 1980.
U.S. Environmental Protection Agency (USEPA). 1989. Guidance on Preparing Superfund Decision
Documents: The Proposed Plan, The Record of Decision, Explanation of Significant Differences, The
Record of Decision Amendment (Interim Final), EPA/540/G-89/007. July 1989.
U.S. Environmental Protection Agency (USEPA). 1999. A Guide to Preparing Superfund Proposed Plans,
Records of Decision, and Other Remedy Selection Decision Documents (Final), EPA 540R-98-031.
July 1999.
U.S. Environmental Protection Agency (USEPA). 1991. Aerial Photographic Analysis of the Cornhusker Army
Ammunition Plant, Grand Island, Nebraska. USEPA Region VII.
Welensiek, M. 1995. Administrative Specialist, CHAAP. Personal communication.

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Record of Decision for Remedial Action (OU3)
Cornhusker Army Ammunition Plant
Final Document