EPA/ROD/R07-97/1431997

EPA Superfund

Record of Decision:

NEBRASKA ORDNANCE PLANT (FORMER)EPA ID: NE6211890011OU 02MEAD, NE04/07/1997

October 1, 1996WCC Project 92KW030M

CommanderU.S. Army Engineer District, Kansas CityATTN: CEMRK-EP-EC (Ms. Rosemary Gilbertson)700 Federal Building601 East 12th StreetKansas City, Missouri 64106-2896

Re: Transmittal of Final Record of Decision for Signature Pages Completion For Operable Unit No. 2 (Groundwater) Former Nebraska Ordnance Plant, Mead, Nebraska Contract No. DACA41-92-C-0023

Dear Ms. Gilbertson:

We are hereby transmitting seven copies of the subject document. We understand that after the signaturepages have been completed, we will distribute copies of the signed document according to the attacheddistribution list.

On September 30, 1996, we transmitted to you 13 pages of this document which showed revisions from thedraft final document in redline/strikeout format. We also copied the transmittal to Mr. Craig Bernsteinof the U.S. Environmental Protection Agency and Mr. Troy Bredenkamp of the Nebraska Department ofEnvironmental Quality. Electronic facsimile was used to make the transmittals.

Please contact us should you have any questions.

Very truly yours,

DISTRIBUTION LIST (After Signature)OF THE FINAL RECORD OF DECISION

OPERABLE UNIT NO. 2FORMER NEBRASKA ORDNANCE PLANT

MEAD, NEBRASKA

Organization CopiesU.S. Army Corps of Engineers 7Kansas City DistrictATTN: CEMRK-EP-EC (Rosemary Gilbertson)

U.S. Army Corps of Engineers Letter of TransmittalKansas City District OnlyATTN: CEMRK-MD-H (Steve Iverson)

U.S. Army Corps of Engineers 1HTRW Center of ExpertiseATTN: HTRW Document Distribution (Ric Hines)

Nebraska Department of Environmental Quality 1ATTN: Mr. Troy Bredenkamp

University of Nebraska Lincoln 1Agricultural Research and Development CenterATTN: Mr. Daniel J. Duncan

U.S. Environmental Protection Agency Region VII 3Waste Management DivisionATTN: Mr. Craig Bernstein

Natural Resources District 1ATTN: Mr. Larry Angle

Nebraska Department of Health 1ATTN: Mr. Scott Petersen

Lincoln Water SystemATTN: Mr. Jerry Obrist

University of Nebraska Hazardous Materials Safety Officer 1ATTN: Mr. Del Weed

Nebraska National Guard 1ATTN: Dave Wunibald

TABLE OF CONTENTS Section Page

1.0 DECLARATION 1-1

2.0 DECISION SUMMARY 2-1 2.1 SITE NAME, LOCATION, AND DESCRIPTION 2-1 2.2 SITE HISTORY AND PREVIOUS INVESTIGATIONS 2-2 2.2.1 Site History 2-2 2.2.2 Previous Investigations 2-4 2.2.3 Summary of OU2 RI Results 2-6 2.3 COMMUNITY PARTICIPATION 2-7 2.4 SCOPE AND ROLE OF OPERABLE UNIT 2 REMEDIAL ACTION WITHIN THE SITE STRATEGY 2-8 2.5 SUMMARY OF SITE CHARACTERISTICS 2-10 2.6 REMOVAL ACTIONS 2-11 2.7 SUMMARY OF SITE RISKS 2-11 2.7.1 Potential Human Health Risks 2-12 2.7.2 Ecological Risk Assessment 2-14 2.8 SUMMARY OF ALTERNATIVES 2-15 2.8.1 Alternative 1 - No Action 2-19 2.8.2 Alternative 2 - Hydraulic Containment 2-20 2.8.3 Alternative 3 - Focused Extraction 2-20 2.8.4 Alternative 4 - Focused Extraction and Soil Excavation 2-21 2.8.5 Alternative 5 - Focused Extraction with Air Sparging 2-21 2.8.6 Alternative 6 - Focused Extraction with Air Sparging and Soil Excavation 2-22 2.8.7 Alternative 7 - Groundwater Extraction 2-23 2.8.8 Alternative 8 - Groundwater Extraction and Soil Excavation 2-23 2.9 TREATABILITY STUDIES 2-24 2.10 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 2-24 2.10.1 Introduction 2-24 2.10.2 Comparison of Alternatives 2-25 2.10.3 Summary 2-31 2.11 THE SELECTED REMEDIAL ACTION 2-32 2.12 STATUTORY DETERMINATIONS 2-33 2.12.1 Protection of Human Health and the Environment 2-33 2.12.2 Compliance with ARARs 2-33 2.12.3 Cost Effectiveness 2-40 2.12.4 Utilization of Permanent Solutions and Innovative Treatment Technologies to the Maximum Extent Practicable 2-40 2.12.5 Preference for Treatment Which Reduces Toxicity, Mobility, or Volume 2-41 2.13 DOCUMENTATION OF SIGNIFICANT CHANGES 2-41

3.0 RESPONSIVENESS SUMMARY 3-1 3.1 OVERVIEW 3-1 3.2 BACKGROUND ON COMMUNITY INVOLVEMENT 3-1 3.3 SUMMARY OF PUBLIC COMMENTS AND AGENCY RESPONSES 3-2 3.3.1 Remedial Alternative Preferences 3-3 3.3.2 Impact on Groundwater Supply 3-9 3.3.3 Reuse of Treated Water 3-10 3.3.4 Nitrates Contamination 3-11 3.3.5 Current Ecological Impacts 3-12

LIST OF FIGURES After Page

FIGURE 1 GENERAL SITE LOCATION MAP 2-1FIGURE 2 SITE MAP 2-1FIGURE 3 AREA OF GROUNDWATER WITH CONCENTRATIONS EXCEEDING FINAL TARGET GROUNDWATER CLEANUP GOALS 2-9FIGURE 4 SOIL EXCAVATION AREAS - FORMER NOP LOAD LINE 1 2-10FIGURE 5 SOIL EXCAVATION AREAS - FORMER NOP LOAD LINE 2 2-10FIGURE 6 SOIL EXCAVATION AREAS - FORMER NOP LOAD LINE 3 2-10FIGURE 7 TYPICAL SOIL EXCAVATION SECTIONS 2-10

LIST OF TABLES

TABLE 1 RANGE OF COC CONCENTRATIONS DETECTED IN MONITORING WELL SAMPLES 2-6TABLE 2 FINAL TARGET GROUNDWATER CLEANUP GOALS 2-15

LIST OF ACRONYMS AFBMD Air Force Ballistic Missile DivisionAOP advanced oxidation processesARARs applicable or relevant and appropriate requirementsARDC Agricultural Research and Development CenterATSDR Agency of Toxic Substances and Disease RegistryCAMUs corrective action management unitsCERCLA Comprehensive Environmental Response, Compensation, and Liability ActCERCLIS Comprehensive Environmental Response, Compensation, and Liability Information SystemCOCs chemicals of concernDNT 2,4 or 2,6-dinitrotolueneDoD Department of DefenseDWEL Drinking Water Equivalent LevelDRE destruction and removal efficiencyFS Feasibility StudyGAC granular activated carbonHA Health AdvisoryHI Hazard IndicesIAG Interagency AgreementMCL Maximum Contaminant LevelIg/L micrograms per literNCP National Oil and Hazardous Substances Pollution Contingency PlanNDEQ Nebraska Department of Environmental QualityNOP Nebraska Ordnance PlantNPDES National Pollutant Discharge Elimination SystemNPL National Priorities ListNRD Natural Resources DistrictO&M operation and maintenanceOU Operable UnitPCB Polychlorinated BiphenylRAOs remedial act