PB97-964607
EPA/541/R-97/051
November 1997
EPA Superfund
Record of Decision:
Elmendorf Air Force Base,
Operable Unit 6 & Source Area SS 19,
Greater Anchorage Borough, AK
12/4/1996
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DCN 97-630-303-13
RCN F33615-90-D-4013 DO 0003
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UNITED STATES AIR FORCE
ELMENDORF AIR FORCE BASE, ALASKA
ENVIRONMENTAL RESTORA TION PROGRAM
OPERABLE UNIT 6 AND SOURCE AREA SS19
RECORD OF DECISION
FINAL
JANUARY 1997
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2.0
3.0
4.0
5.0
PART I.
PART II.
1.0
TABLE OF CONTENTS
Page
DECLARATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-I
DECISION SUMMARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. I-I
INTRODUCTION................................ ....................... . . I-I
1.1
1.2
1.3
1.4
1.5
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-I
Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Scope and Role of Response Action. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-6
Community Participation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-6
Source Area SS 19 [[[ 1-8
SOURCE WP 14 [[[ 2-1
2.1
2.2
2.3
2.4
2.5
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . 2-5
Remedial Action Objectives, Alternatives, and Comparative Analysis . .
for WP 14 [[[ 2-23
Selected Remedy for WPI4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-28
SOURCE LF04 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 .
3.1
3.2
3.3
3.4
3.5
Site Description. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . 3-4
Remedial Action Objectives, Alternatives, and Comparative Analysis for LF04 .. 3-25
Selected Remedy for LF04 ............................................ 3-28
SOURCE SO 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1
4.2
4.3
4.4
4.5
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Site History and Enforcement Activities. . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . 4-5
Remedial Action Objectives, Alternatives, and Comparative Analysis
for SO 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18
Selected Remedy for SO 15 ............................................ 4-29
SOURCE LF02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1
5.2
5.3
5.4
5.5
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Site History and Enforcement Activities. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
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8.0
PART III.
6.0
6.1
6.2
6.3
6.4
6.5
TABLE OF CONTENTS (CONTINUED)
Page
SOURCE LF03 ., . . . ..,. . ... .. . ... ... . . . . . .. .. .. .. . ... . . . . . '.' . . .. . . ... .. . . . 6-1
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . , , . . . . . . . 6-4
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . , . . , . . 6-4
Remedial Action Objectives, Alternatives, and Comparative Analysis for LF03 .. 6-14
Selected Remedy for LF03 .......,...................................., 6-14
7.0
SOURCE SD73 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , , . . . , . . . . . , 7-1
7.1
7.2
7.3
7.4
7.5
Site Description, . .. . . . . . . . . . . , . . . . . , . . . , . . . , . . . . . . . . . . . . . . . . . . . . . . . . 7-1
,Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . , . . 7-3
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . 7-3
Remedial Action Objectives, Alternatives, and Comparative Analysis for SD73 .. 7-12
Selected Remedy for SD73 ....,...................................,... 7-13
REFERENCES, . . . , . . . . . . . . . . . . . . . . . , . .'. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . 8-1
RESPONSIVENESS SUMMARY. . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . .. III-I
APPENDIX A: Index to OU 6 Documents in Administrative Record
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ACRONYM LIST
AAC = Alaska Administrative Code
ACM = Alaska Cleanup Matrix for non-UST Soils.
ADEC = Alaska Department of Environmental Conservation
AFB = Air Force Base
ARARs = Applicable or Relevant and Appropriate Requirements
AS Alaska Statute
BESG = Elmendorf Bioenvironmental Engineering Services Group
bgs = Below Ground Surface
CERCLA = Comprehensive Environmental Response, Compensation, and Liability
Act of 1980
CFR Code of Federal Regulations
em/see = Centimeters Per Second
COC = Contaminant ofConcem
CaE = Corps of Engineers
CSF = Cancer Slope Factor
DCA = Dichloroethane
DCE = Dich loroethene
DRMO = Defense Reutilization and Marketing Office
ELCR = Excess Lifetime Cancer Risks
ERA . = Ecological Risk Assessment
EQ = Ecological Quotients
FFA = Federal Facilities Agreement
FAA = Federal Aviation Administration
FS = Feasibility Study
ftJday = Feet Per Day
HEAST = Health Effects Assessment Summary Table
HI = Hazard Index
HRA = Health Risk Assessment
HVOC = Halogenated Volatile Organic Compound
ICIR = Institutional Controls with Intrinsic Remediation
IRIS = Integrated Risk Information System
IRP = Installation Restoration Program
LFI = Limited Field Investigation
MCL Maximum Contaminant Level
mg/kg Milligrams Per Kilogram
msl = Mean Sea LeveJ
NCP = National Oil and Hazardous Substances Pollution Contingency Plan
NFA = No Further Action
NOAA = National Oceanographic and Atmospheric Administration
O&M = Operation and Maintenance
OU = Operable Unit
PCA T etrach loroethane
PCBs Polychlorinated Biphenyls
POL = Petroleum Oils and Lubricants
ppmv = Parts Per Million by Volume
PVC = Polyvinyl Chloride
RAO = Remedial Action Objective
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ACRONYMS (CONTINUED)
RCRA = Resource Conservation and Recovery Act
RID = Reference Dose
RI = Remedial Investigation
RIfFS = Remedial [nvestigationlFeasibility Study
RME = Reasonable Maximum Exposure
ROD = Record of Decision
SARA = Superfund Amendments and Reauthorization Act
SERA = State-Elmendorf Environmental Restoration Agreement
SVOC = Semi-Volatile Organic Compound
TBC = T 0- Be-Considered
TCA = I, I , I-Trichloroethane
TCE = Trichloroethene
UCL = Upper Confidence Limit
UDRO Unidentified Diesel Range Organics
J..Lg/L = Micrograms Per Liter
UGRO = Unidentified Gasoline Range Organics
USAF United States Air Force
USC = United States Code
USEPA = United States Environmental Protection Agency
USGS = United States Geological Survey
UST = Underground Storage Tank
VOC = Volatile Organic Compound
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PART I
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PART I. DECLARATION
SITE NAME AND LOCATION
Elmendorf Air Force Base (AFB)
Operable Unit (OU) 6
Elmendorf Air Force Base, Alaska
STATEMENT OF BASIS AND PURPOSE
This. Record of Decision (ROD) presents the selected remedial action for OU 6 at
Elmendorf AFB. It was developed 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), 42 U.S. Code (USC) ~ 960 I et seq.. and to the extent practicable,
in accordance with the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40
Code of Federal Regulations (CFR) ~ 300 ~ The attached administrative record index
(Appendix A) identifies the documents upon which the selection of the remedial action was based.
OU 6 is the last operable unit to be investigated at Elmendorf AFB, and as such is
comprised of a mixed assemblage of source areas. It is composed ofthree former landfills (LF02, LF03,
and LF04), two sludge disposal pits (SO 15 and WP 14), and a surface disposal area around a rock testing
laboratory (SD73). The ROD also addresses an additional source area, a fonner storage bunker
designated SS 19.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances including fuels, fuel constituents,
and halogenated volatile organic compounds from this OU, if not addressed by implementing the
response act'ion selected in this ROD, could present an imminent or substantial endangerment to pubiic
health, welfare, or the environment. Specific hazardous substances include constituents such as benzene,
toluene, trichloroethene, and tetrachloroethane.
DESCRIPTION OF THE SELECTED REMEDIES
The selected remedies were chosen from many alternatives as the best methods of
addressing contaminated groundwater and soil within the various source areas in OU 6. The selected
remedies address the associated risks by a combination of actions to reduce contamination below cleanup
levels for OU 6 established in this ROD and institutional controls to prevent exposure to contamination
above those cleanup levels. This is the last operable unit to be investigated at Elmendorf AFB and is
intended to be the final ROD for this base.
The U.S. Air Force (USAF), the U.S. Environmental Protection Agency (USEPA), and
the State of Alaska, through the Department of Environmental ConserVation (ADEC), concur with the
selected remedies. The major components of the selected remedies which address the principle threats
posed by the conditions within the OU 6 source areas include:
I-I
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Source Area WP14:
Groundwater at WPI4:
.
Institutional controls on land use and water use, as specified in the Base Comprehensive
Plan, will restrict access to the contaminated groundwater throughout WP14.
Installation of wells in the contaminated plume for residential, industrial, and
agricultural use will be prohibited by the Base Comprehensive Plan until cleanup levels
have been achieved.
.
Groundwater will be monitored semi-annually and evaluated annually to determine
contaminant migration and to track the progress of contaminant degradation and
dispersion, as well as to provide an early indication of unforseen environmental or
human health risk. Five-year reviews will also assess the protectiveness of the remedial
action, including an evaluation of any changed site conditions, as long as contamination
remains above cleanup levels.
.
Recoverable quantities offree product found on top of the water table at WP 14 will be
regularly removed during groundwater monitoring events.
.
Groundwater monitoring will be discontinued if contaminant levels are below cleanup
levels during two consecutive monitoring events. In that case, no further action for
groundwater will be required.
.0
During the final round of monitoring, samples will be collected and analyzed for all
constituents that exceeded maximum contaminant levels (MCLs) during the 1994
investigation including volatile organic compounds (VOCs), semi-volatile organic
compounds (SVOCs), and metals. These results will be evaluated before a final
determination is made that groundwater meets all cleanup requirements.
.
All groundwater is expected to be cleaned up within 14 years.
Soil at WPI4:
.
No further action will be required for the soil at WP 14.
Source Area LF04:
Groundwater at LF04 NorthlBeach:
.
No further action is required for the groundwater at LF04 NorthlBeach.
Groundwater at LF04 South:
.
Access to groundwater at LF04 South will be institutionally controlled. LF04 is
currently designated as a "restricted use area" in the Base Comprehensive Plan. This
designation provides for recreational use of the parcel (cross country skiing, etc.) and for
construction of unmanned facilities such as a parking lot, storage building, or taxiway,
but prohibits the construction of any sort of manned facility such as an office building or
1-2
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a residence. Drilling into. the shallaw aquifer is also. restricted by the Base
Camprehensive Plan. As a farmer landfill, LF04 will maintain this designatian
indefinitely. .
.
Groundwater will be manitared and evaluated annually to. detennine cantaminant
m igratian and to. track the pragress af cantaminant degradatian and dispersian, as well as
to. provide an early indicatian afunfarseen enviranmental ar human health risk. Five-
year reviews will also. assess the pratectiveness afthe remedial actian, including an
evaluatian af any changed site canditians, as lang as cantaminatian remains abave
cleanup levels.
.
Recaverable quantities affree product faund an tap afthe water table at LF04 will be
regularly remaved during graundwater manitaring events.
.
Graundwater manitaring will be discantinued if cantaminant levels are belaw cleanup
levels during two. cansecutive manitaring events. In that case, no. further actian far
groundwater will be required.
.
During the final round af manitaring, samples will be callected and analyzed far all
canstituents that exceeded MCLs during the 1994 investigatian including VOCs,
SVOCs, and metals. These results will be evaluated befare a final detenninatian is made
that graundwater meets all cleanup requirements.
.
All groundwater is expected to. be cleaned up within 14 years.
Sail at LF04 NarthlBeach:
.
Access to. sail at LF04 NarthlBeach will be institutianally cantralled. LF04 is currently
designated as a "restricted use area" in the Base Camprehensive Plan. This designatian
pravides far recreatianal use of the parcel (crass cauntry skiing, etc.) and far
canstructian af unmanned facilities such as a parking lat, starage building, ar taxiway,
but prahibits the canstructian af any sart af manned facility such as an affice building ar
a residence. As a farmer landfill, LF04 will maintain this designatian indefinitely.
..
No. further actian is required far sail cantaminatian at LF04 NarthlBeach; hawever,
landfill debris an the beach fram LF04 will be remaved annually as the specific remedy
far this area.
.
The remaval af debris will include all LF04 landfill material which has fallen anta the
beach which can be reasanably collected far dispasal, as well as debris an the bluff slape
ar ather law lying areas which can be accessed and remaved withaut hazard.
.
Hazardous materials encountered during the annual remaval events will be handled
according to appropriate regulatians.
.
The remaval af debris fram the beach at LF04 is expected to. cantinue annually far 30
years ar as lang as the landfill remains subject to. erasianal actian by tides. Five-year
reviews will assess the pratectiveness afthe remedial actian, including an evaluatian af
any changed site canditians.
1-3
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.
No further action will be required as a means of closing the LF04 landfill.
Soil at LF04 South:
.
No further action is required for the soil at LF04 South.
Source Area SDIS:
Perched Aquifer Groundwater at SO 15:
.
Institutional controls on land use and water use, as specified in the Base Comprehensive
Plan, will restrict access to the contaminated groundwater throughout SOlS. Installation
of wells in the contaminated plume for residential, industrial, or agricultural use will be
prohibited by the Base Comprehensive Plan until cleanup levels have been achieved.
.
Groundwater in the perched aquifer at SO 15 will be treated by a high-vacuum extraction
process to remove fuel related contaminants and halogenated volatile organic
compounds (HVOCs).
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Recoverable quantities of free product found on top of the water table at SO 15 will be
removed through the high-vacuum extraction process.
.
Treated water will be reinjected into the subsurface beyond the boundary of the
contaminated aquifer. Reinjected water will be regularly monitored to ensure it meets
cleanup and risk requirements.
.
Groundwater remaining above cleanup levels will continue to be monitored semi-
annually and evaluated annually to determine contaminant migration and to track the
progress of the high-vacuum extraction treatment, as well as to provide an early
indication of unforseen environmental or human health risk. Five-year reviews will also
assess the protectiveness of the remedial action, including an evaluation of any changed
site conditions, as long as contamination remains above cleanup levels.
.
When two consecutive groundwater monitoring events indicate contaminant
concentrations are below cleanup levels, the high-vacuum extraction system will be shut-
off. Semi-annual monitoring will continue for another year, and subsurface soil samples
will be collected. If levels are confirmed to be below cleanup levels one year after the
system was shut-off, no further remedial action will be required. If contamination is
present in any of the samples, the system will be restarted, or another remedial option
will be considered.
.
During the final round of groundwater monitoring, samples will be collected and
analyzed for all constituents that exceeded MCLs during the 1994 investigation
including VOCs and arsenic. These results will be evaluated before a final decision is
made that groundwater meets all cleanup requirements.
.
All groundwater is expected to be cleaned up within 5 years.
1-4
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Deep Aquifer Groundwater at SO 15:
.
No further action is required for the deep aquifer groundwater at SO 15.
Soil at SOlS:
.
Shallow soils (less than 5 feet deep) with contamination above cleanup levels will be
excavated, removed, and thermally treated to eliminate fuel-related contaminants. After
treatment, no further action will be required for the shallow soils.
.
Deep soils at SO 15 will be actively treated through air stripping associated with the
high-vacuum extraction process described for the perched aquifer groundwater.
.
Soils with contami':lation above cleanup levels will be sampled one year after system
start up and every 3 years thereafter to evaluate contaminant migration and timely
reduction of contaminant concentrations by high-vacuum extraction. If cleanup levels
are not being achieved, further remedial action will be evaluated. This will include
5-year reviews to assess the protectiveness of the remedial action, including an
evaluation of any changed site conditions, as long as contamination remains above
cleanup levels.
.
When two consecutive groundwater monitoring events indicate contaminant
concentrations are below cleanup levels, the high-vacuum extraction system will be shut-
off. Semi-annual monitoring will continue for another year, and subsurface soil samples
will be collected. If levels are confirmed to be below cleanup levels one year after the
system was shut-off, no further remedial action will be required. If contamination is
present in any of the samples, the system will be restarted, or another remedial option
will be considered.
.
All soils are expected to be cleaned up within 5 years.
lurce Area LF02:
Groundwater at LF02 (Including Seeps):
.
Access to groundwater at LF02 will be institutionally controlled. LF02 is currently
designated as a "restricted use area" in the Base Comprehensive Plan. This designation
provides for recreational use of the parcel (cross country skiing, etc.) and for
construction of unmanned facilities such as a parking lot, storage building, or taxiway,
but prohibits the construction of any sort of manned facility such as an office building or
a residence. Drilling into the shallow aquifer is also restricted by the Base
Comprehensive Plan. As a former landfill, LF02 will maintain this designation
indefinitely.
.
Groundwater will be monitored semi-annually and evaluated annually to determine
contaminant migration and to track the progress of contaminant degradation and
dispersion, as well as to provide an early indication of unforseen environmental or
human health risk. Five-year reviews will also assess the protectiveness of the remedial
1-5
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action, including an evaluation of any changed site conditions, as long as contamination
remains above cleanup levels.
.
Groundwater monitoring will be discontinued if contaminant levels are below cleanup
levels during two consecutive monitoring events. In that case, no further action for
groundwater will be required.
.
During the last round of groundwater monitoring, samples will be collected and analyzed
for all constituents that exceeded MCLs during the 1994 investigation, including VOCs
and SVOCs. These results will be evaluated before a final determination is made that
groundwater meets ~II cleanup requirements.
.
All groundwater is expected to be cleaned up within 23 years.
Soil at LF02:
.
Access to soil at LF02 will be institutionally controlled. LF02 is currently designated as
a "restricted use area" in the Base Comprehensive Plan. This designation provides for
recreational use of the parcel (cross country skiing, etc.) and for construction of
unmanned facilities such 'as a parking lot, storage building, or taxiway, but prohibits the
construction of any sort of manned facility such as an office building or a residence. As
a former landfill, LF02 will maintain this designation indefinitely.
.
A limited soil cover will be applied in three areas with elevated lead concentrations at
LF02. This will eliminate the pathway for contact with the lead contamination. Five-
year reviews will be conducted to evaluate the integrity ofthe cover, evaluate impacts
from any changed site conditions, and assess the continued protectiveness of this
remedial action.
.
Landfill debris on top of or protruding from the ground surface at LF02 will also be
removed as part of the specific remedy for this area.
.
Hazardous materials encountered during the removal event will be handled according to
appropriate regulations.
.
No further action will be required as a means of closing the LF02 landfill.
Source Area LF03:
Groundwater at LF03:
.
No further action is required for the groundwater at LF03.
Soil at LF03:
.
No further action is required for the soil at LF03.
.
No further action will be required as a means of closing the LF03 landfill.
(-6
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Source Area SD73:
Groundwater at S073:
.
No further action is required for the groundwater at S073.
Soil at S073:
.
No further action is required for the soil at S073.
No further action is required for soil or groundwater at Source Area SS 19, which is also addressed in this
Record of Decision.
STATUTORY DETERMINATIONS
The selected remedies are protective of human health and the environment, comply with
federal and state requirements that are legally applicable or relevant and appropriate to the remedial
action, and are cost-effective. These remedies utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable, and satisfy the statutory preference for remedies that
employ treatment that reduces toxicity, mobility, or volume as a principal element for groundwater and
soil.
The selected remedies will result in contaminants remaining on-site above health-based
levels. A review will be conducted within 5 years after commencement of remedial action. The review
will ensure that the remedies continue to provide adequate protection of human health and the
~nvironment.
1-7
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LEAD AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
ELMENDORF AIR FORCE BASE, OPERABLE UNIT 6
This signature sheet documents the U.S. Air Force acceptance of the Record of Decision for Operable
Unit 6 at Elmendorf Air Force Base.
a7-JAN 7'7-
Date
~UGE D. SANTARELLI, Lt Gen, USAF
:hai an, HQ PACAF
~nvironmental Protection Committee
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LEAD AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
ELMENDORF AIR FORCE BASE, OPERABLE UNIT 6
This signature sheet documents United States Environmental Protection Agency acceptance of the
Record of Decision for Operable Unit 6 at Elmendorf Air Force Base.
~~
:HUCK CLARKE
~egional Administrator
~egion X
J.S. Environmental Protection Agency
{ 2--4 .&it,
Date
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SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
ELMENDORF AIR FORCE BASE, OPERABLE UNIT 6
"he Alaska Department of Environmental Conservation concurs with the Record of Decision for
)perable Unit 6 at Elmendorf Air Force Base.
d'
~ 7~ 74-.%
,T DRIKSSON
'irector. Spill Prevention and Response
laska Department of Environmental Conservation
1/:2.1'1r
Date
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PART II
DECISION SUMMARY
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Section 1.0
INTRODUCTION.
This Decision Summary provides an overview of the problems posed by the
contaminants at Elmendorf Air Force Base (AFB) Operable Unit (OU) 6. It identifies the areas
considered for remedial response, describes the remedial alternatives considered, and analyzes those
alternatives compared to the criteria set forth in the National Contingency Plan (NCP). The Decision
Summary explains the rationale for selecting the remedy, and how the remedy satisfies the statutory
requirements of the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA).
The decision summary for OU 6 is divided by source area due to the diversity
encountered between the six source areas within the OU. Reference is made to those discussions which
are generic to the entire operable unit between the various source area sections to avoid redundancy.
One additional source outside ofOU 6 is also briefly addressed in this decision summary.
The following subsections describe the general setting of Elmendorf AFB and OU 6,
including a brief physical description, discussion of the OU 6 land use, hydrogeology, and groundwater
use. The OU 6 site history and enforcement activities, including the identification of activities which led
to the current contamination at au 6, the OU 6 regulatory and enforcement history, the role ofthe
response action, and community participation, are also addressed in this'introductory section. Source
area specific historical and enforcement activities, as well as detailed site descriptions, are provided in
the specific source area sections. Source Area SS 19 is also discussed in this section. This source is not
included within OU 6, but is addressed in this Record of Decision (ROD).
1.1
Site Description
The following subsections describe the physical description, land use, groundwater use,
and hydrogeology of OU 6.
1.1.1 '
Physical Description
Elmendorf AFB is located approximately 2 miles north of downtown Anchorage
(Figure 1.1-1). The base provides defense for the United States through surveillance, logistics, and
communications support. OU 6 is the final OU at Elmendorf AFB, and consists of six source areas,
including WP14, LF04, SOlS, LF02, LF03 and SD73. These sites are located across the base, as
depicted in Figure 1.1-2. Three of these sites are located on the northern portion of the base, on what is
known as the Elmendorf Moraine. These are Sources WPl4 [Petroleum, Oils, and Lubricants
(POL) Sludge Disposal Site No. I], LF04 (the Knik Bluff Landfill), and SOlS (POL Sludge Disposal
Site No.2). The other three sources are located in the southeastern portion ofthe base on the glacial
outwash plain south of Ship Creek. These are Sources LF02 (a landfill located west of the Davis
Highway and Oil Well Road), LF03 (the Hospital Road Landfill), and SD73 (the surface disposal area
surrounding a former United States Geological Survey rock testing laboratory).
In general, the OU 6 source areas are in undeveloped areas of the base and are heavily
vegetated with trees or shrubs. The exception to this is SD73, which has a primary cover of grass or
weeds. The OU 6 source areas range in size from several acres to several tens of acres and are primarily
devoid of buildings or other significant man-made features other than unimproved gravel roads. More
detail on each source area is provided in the source area specific sections.
January 1997
I-I
OU 6 ROD, Final
'C
-------
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Figure 1.1-1. Elmendorf AFB Site Location Map
au 6 ROD, Final
.-2
January 1997
-------
;' " .~ ',' ::~ r '"
TABLE OF CONTENTS
PART II DECISION SUMMARY
Page
1.0
1.1-1
1.1-2
INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-I
1.1
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1. 1.1 Physical Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1.2 Land Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . " 1-4
1.1.3 Hydrogeology and Groundwater Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-4
Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-5
1.2.1 Identification of Activities Leading to the Current Contamination
at OU 6 [[[ 1-5
1.2.2 Regulatory and Enforcement History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Scope and Role of Response Action. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Community Participation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Source Area SS 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . ; . . . . . . . . . . . . . . . . . . . . . . . . .. 1-8
1.2
1.3
1.4
1.5
LIST OF FIGURES
Elmendorf AFB Site Location Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Page
-------
[This page intentionally left blank.]
"-<:
-------
1
North
o
Scale
.5
Miles
.*
~
~
Source
LF04
CD 1 c
tI ~ i~
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-10
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\ Source
. \ SS19
~
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1
Source
LF02
Figure 1.1-2. Location ofOU 6 Source Areas and Source Area SSI9
January 1997
OU 6 ROD, Final
1-3
-------
Land Use
The land use for OU 6 is either open space or "restricted." Each of the fonner OU 6
landfills have building restrictions as addressed in the Base Comprehensive Plan. None of the OU 6 sites
have been developed for industrial or residential purposes, with the exception of S073, which has been
used for light industrial activities in the past. Land use for SD73 may be changed to residential in the
future.
1.1.2
Hydrogeology and Groundwater Use
The OU 6 source areas are located in two major hydrogeologic regimes, known as the
"outwash plain" and the "Elmendorf Moraine." The glacial outwash plain is composed predominantly of
sand and gravel. The moraine is composed primarily of sands, silts, and clays. In general, two aquifers
underlie the base, an unconfined shallow aquifer and a deep confined aquifer. The aquifers are separated
by the Bootlegger Cove Fonnation, which is an impenneable layer composed of silts and clays. Block
diagrams depicting the hydrogeologic conceptual model for each source area, including the identification
. of each aquifer, are presented in the specific source area sections.
1.1.3
The hydrogeology of the shallow aquifer differs substantially between the moraine and
outwash plain source areas due to the different lithologies present. For this reason, the shallow aquifer is
described in detail in the source area specific sections, a'ong with the groundwater use for that aquifer.
Since the Bootlegger Cove Formation was only encountered at LF04, limited site specific information is
available for that fonnation. As a consequence, it is described generically below, along with the deep
confined aquifer, which was not encountered during the OU 6 Remedial Investigation/Feasibility Study
(RIIFS). It is anticipat~d, but not con finned, that the Bootlegger Cove fonnation and the deep confined
aquifer underlie all of the OU 6 source areas.
The Bootlegger Cove Fonnation is made up of a series of clays, sands, and silts, which
interfinger with the coarser grained units of the shallow aquifer above. The Bootlegger Cove is typically
about 50 feet thick, but its actual thickness has only been measured in limit~d areas on base. The top of
the Bootlegger Cove should occur at a depth of approximately 100 feet below ground surface (bgs)
underlying the OU 6 source areas on the outwash plain, and approximately 170 feet bgs on the moraine.
This fonnation outcrops along the beach at LF04.
The deep aquifer at OU 6 underlies and is confined by the Bootlegger Cove Formation,
and occurs at an estimated depth of between ISO feet bgs (outwash plain), and 220 feet bgs (moraine).
This aquifer is up to 550 feet thick. While the Bootlegger Cove Formation forms the principal confining
unit, the confined aquifer may also be overlain by substantial thicknesses of other fine grained materials.
Groundwater flow in the aquifer is to the west-northwest toward Knik Ann.
The deep aquifer at Elmendorf AFB has supplied large quantities of water for light
industrial use such as air conditi9ning cooling water (no treatment), and aircraft and vehicle wash water
(chlorination only) in the past. There are several inactive or abandoned base wells believed to be
screened in the deep aquifer near OU 6. None of these wells were sampled during the Remedial
Investigation (RI). Base Well 50, near S073, was believed to be screened in the deeper aquifer but was
found to be screened in the shallow aquifer during the RI. This well was inactivated during the
investigation. The base wells screened in the deep aquifer are used for backup drinking water supply.
A hydraulic communication test conducted at Base Well 42 in OU 2 indicated there is no
communication between the shallow aquifer and the confined aquifer. This result, coupled with the
comparison of data from base water supply wells screened in the deep aquifer and data collected from
OU 6 ROD, Final
1-4
January 1997
-------
nearby wells screened in the shallow aquifer, demonstrate the competency of the Bootlegger Cove
Fonnation as an aquitard between the unconfined and confined aquifers.
1.2
Site History and Enforcement Activities
The following subsections detail the contaminant history of au 6, the regulatory and
enforcement history, the role of the response action, and the role of the community in defining the
response.
1.2.1
Identification of Activities Leading to the Current Contamination at OU 6
au 6 is composed of three fonner landfills, two sludge disposal pits, and a surface
disposal area around a rock testing laboratory. Past landfill and general waste management practices are
the principal reason for the contamination present at these sites. In addition, several fuel lines and the
associated valves and storage tanks associated with the base fueling facilities are located within au 6
source areas. These fuel systems have, at times, leaked fuel into the soil and groundwater surrounding
these facilities. Specific activities leading to the current contamination at au 6 are addressed in the
source area specific sections in this Record of Decision (ROD).
The activities which contributed to past contamination at au 6 are no longer taking
place. The landfills have been closed since the early 1980s, and surface disposal of fuel wastes has not
been conducted since 1983. As far as fuel related leaks are concerned at OU 6, the POL lines at LF04
and WPI4 have been tested and detennined to be sound. In addition, the underground storage tank
(UST) and associated contaminated soils in the vicinity of the pumphouse (Building 30-790) at LF04
were removed in 1996, and the pumphouse was taken out of service.
Environmental investigations have been conducted at au 6 since the early 1980s.
Several studies discovered evidence of contamination in various parts of OU 6. The majority of these
investigations were broadly focused across Elmendorf AFB and covered only portions of the source
areas currently included in au 6.
The first investigation to examine contamination throughout much of the area was done
in 1990 (Black and Veatch, 1990). Only WPI4, LF03, and SOlS were addressed in this investigation.
The initial study was followed in 1993 by a Limited Field Investigation (LFI) of SOlS (Radian, 1993b)
and an Environmental Baseline Assessment (Radian, 1993a) where S073 was investigated further.
Additionally, the State-Elmendorf Environmental Restoration Agreement (SERA) Phase I B Site
Assessment (ENSR, 1993) reevaluated contamination at LF02. Following these investigations, a full
scale Remedial Investigation (RI) was conducted at au 6 in 1994. The RI detennined the nature and
extent of contamination, and the potential risks to public health and the environment. The results were
compiled and analyzed in the RI report (USAF, I 996b). Alternatives for remedial action were evaluated
in detail in the au 6 Feasibility Study (FS), submitted with the RI in January of 1996 (USAF, 1996b).
The RlIFS concluded that soil was contaminated in limited areas with fuel constituents
resulting from past waste management activities, or leaking abandoned fuel pipelines. Areas of exposed
landfill debris were also identified, with associated lead contamination at LF02. Several specific sources
of groundwater contamination were identified, including the fuel lines at LF04 and WP14, the
pumphouse at LF04, and the sludge weathering pads at SOlS. Solvent contamination was also identified
at SO 15 and was attributed to the waste management activities conducted at that site.
1.2.2
Regulatory and Enforcement History
Based on the results of environmental investigations, Elmendorf AFB was listed on the
January 1997
1-5
au 6 ROD, Final
-------
o National Priorities List by the U.S. Environmental Protection Agency (USEPA) in August 1990. This
listing designated the facility as a federal site subject to the remedial response requirements of the
Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), as amended by
the Superfund Amendments and Reauthorization Act of 1986 (SARA). On 22 November 1991, the U.S.
Air Force (USAF), the USEPA, and the Alaska Department of Environmental Conservation (ADEC)
signed the Federal Facilities Agreement (FF A) for Elmendorf AFB. The contaminated areas of
Elmendorf AFB were divided into seven OUs, each to be managed as a separate region and investigated
according to varying schedules.
Scope and Role of Re$ponse Action
OU 6 is the last Operable Unit to be investigated at Elmendorf AFB, and as such is
comprised of a mixed assemblage of source areas. OU 6 was originally defined in the FF A to include
only LF04, WP14, and LF03. LF02 was added in late 1993 after the evaluation ofthe SERA Phase IB
Site Assessment results (ENSR, 1993). Similarly, Source Area SDI5 was added to OU 6 in 1993 based
upon the conclusions reached in the Limited Field Investigation (LFI) conducted at that site (Radian,
1993b), and S073 was added following evaluation ofthe results of an Environmental Baseline
Assessment conducted at the National Oceanographic and Atmospheric Administration (NOAA) facility
where SD73 is located (Radian, I 993a).
1.3
In accordance with the FFA, an RI ofOU 6 was conducted in the summer of 1994. The
RI determined the nature and extent of contamination, and the potential risks to public health and the
environment. The results were compiled and analyzed in the R1 Report (USAF, 1996b). The RI
concluded that fuel, fuel constituents, and low levels of solvents were present in soil and groundwater in
OU 6. Low levels of pesticides and other contaminants were also found. Isolated areas of elevated fuel
constituents were detected in the soils at the location of leaks or spills. In addition, plumes of dissolved
fuel. and solvent constituents were identified in the groundwater.
The Final RIIFS was submitted in January 1996 (USAF, I 996b). A Proposed Plan
(USAF, 1996a) was distributed to the public on I April 1996, and a public meeting to discuss the plan
was held on 17 April 1996. The index of documents entered into the Administrative Record for OU 6 is
provided as Appendix A.
The CERCLA process described above is intended to identify solutions to contami-
nation issues where they exist. The remedial action described in this ROD addresses threats to human
health and the environment posed by contamination at OU 6. The RIIFS Report defines these threats as
both groundwater and soil contaminants. At this time, both soil and groundwater will be actively treated
where the contaminants pose a significant future threat to human health. Groundwater and soil will both
be monitored to evaluate contaminant migration, and to track the progress of contaminant dispersion and
degradation, as well as to provide an early warning of any unforseen environmental or human health risk.
In addition, contaminated landfill soil will be covered with a clean soil cover, and landfill debris exposed
at the surface will be removed and disposed. Further response actions, coordinated with the regulatory
agencies, may be considered if monitoring finds unacceptable contaminant migration occurring, or
unacceptable reduction in contaminant concentrations over time..
Communi(y Participation
Public participation has been an important component of the CERCLA process at
Elmendorf AFB. Activities aimed at informing and soliciting public input regarding base environmental
programs include:
1.4
OU 6 ROD, Final
1-6
January 1997
-------
.
.
.
.
.
.
.
Environmental Update: Environmental Update is a newsletter distributed to the
community and interested parties. It discusses the progress that has been made on au
and advises the public about opportunities to provide input concerning decisions to
address contaminated areas of the base. Aspects of the OU 6 CERCLA progress have
been published in this newsletter.
.
Community Relations Plan: The base environmental personnel maintain and regularly
update a Community Relations Plan. It describes how the base will inform the public of
base environmental issues, and it solicits public comment on base environmental
programs.
.
Tbe Restoration Advisory Boardtrecbnical Review Committee: Base personnel
meet regularly with representatives of the community to discuss base environmental
programs and solicit their comments.
.
Public Worksbops: On 5 February 1992, approximately 75 people attended a public
workshop where base personnel discussed base environmental programs and encouraged
public participation.
.
Videotape: Base personnel made a videotape describing base environmental activities.
The tape is shown to base employees as well as the general public. .
Speaken Bureau: The 3rd Wing Public Affairs Office maintains a speakers bureau
capable of providing speakers versed in a variety of environmental subjects to military
and civic groups.
Newspaper Releases: News releases are published on significant events during the
Installation Restoration Program (IRP). News releases are made announcing all public
meetings that are held to discuss proposed remedial actions.
Information Repositories: Public access to technical documents is provided through
information repositories located at the Bureau of Land Management's Alaska Resources
Library and the University of Alaska at Anchorage's Consortium Library. The
information in the repositories is also maintained in the administrative record.
Display Board: During public functions, a display board, showing key elements and
progress of the ElmendorfIRP, is used to communicate technical issues to the public. It
is used during both on-base and off-base events.
Proposed Plan: The au 6 Proposed Plan was distributed to the public on 1 April 1996,
a public meeting was held 17 April 1996, and the public review period was from 2 April
to 3 May 1996. Comments from the public are contained in Part HI, Responsiveness
Summary, of this document.
Public Notice: Public notices have been issued prior to all significant decision points in
the IRP. For OU 6, public notice was issued for the Proposed Plan in the Anchorage
Daily News (3/31/96) and the Sourdough Sentinel (3/29/96).
January 1997
OU 6 ROD, Final
1-7
-------
.
Mailing List: A mailing list of parties interested in the restoration program is
maintained by the base. Notices and publications (news releases including the OU 6
Proposed Plan meeting) are released via the mailing list.
.
Responsiveness Summary: Public comments were received on the OU 6 Proposed
Plan. The USAF maintains a record of all comments and has published responses to the
comments in this ROD. .
All decisions made for OU 6 were based on information contained in the Administrative Record. An
index to the documents contained in the Administrative Record for OU 6 is provided as Appendix A.
Source Area SS19
In addition to the six source areas addressed as part ofOU 6, one additional source area,
SSI9, is included in this ROD. SS19 consists of a bunker in the extreme northeast comer of the
base (Figure 1.1-2). This building was used during the early 1960s to temporarily store pesticides before
disposal. No records indicate that spills or releases have occurred. This building is currently used by the
Base Civil Engineering Squadron for equipment storage.
1.5
A Limited Field Investigation (LFI) was conducted at this site in 1993. During the LFI,
surface and subsurface soil samples were collected and analyzed for pesticides. Laboratory analyses of
the samples indicated dieldrin was present above risk based concentrations and soil action levels in soils
at depths ranging from 0 to 3 feet. As a result of the LFI, it was determined that no further action would
be warranted at this site if contaminated soils were removed.
In 1995, soil was excavated from the west side of the bunker to one foot below grade.
Samples taken at the base of the excavation indicated that dieldrin was still present in some areas of the
initial excavation. These areas were further excavated an additional foot below grade. Following this,
confirmatory base and sidewall samples indicated that all pesticide contaminated soils had been removed
down to a risked-based level of 136 parts per billion (ppb), a concentration at which the residual risk is
within an acceptable range (5.1 E-06) assuming residential use and exposure. The site was backfilled
with clean granular fill material. Because the contaminated soils at SS 19 have been satisfactorily 0
removed, and the residual risk is at an acceptable level, no further action is required.
OU 6 ROD, Final
1-8
January 1997
-------
SECTION TWO
-------
2.1-1
2.1-2
2.2-1
2.3-1
2.5-1
T ABLE OF CONTENTS
Page
2.0
SOURCE WPI4 [[[ 2-1
2.1
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.1.1 Land Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.1.2 Hydrogeology and Groundwater Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
2.2.1 Identification of Activities Leading to the Current Contamination
at WP 14 [[[ 2-4
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . . 2-5
2.3.1 Nature and Extent of Contamination ............................... 2-5
2.3.2 Risk Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15
2.3.3 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20
Remedial Action Objectives, Alternatives, and Comparative Analysis
for WPI4 [[[ 2-23
2.4.1 Remedial Action Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
2.4.2 Groundwater Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
2.4.3 Summary of Comparative Analysis of Groundwater Alternatives. . . . . . . . . 2-26
2.4.4 Soil Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-28
2.4.5 Summary of Comparative Analysis of Soil Alternatives. . . . . . . . . . . . . . . . 2-28
Selected Remedy for WP14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-28
2.5.1 Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-31
2.5.2 Documentation of Significant Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-33
2.2
2.3
2.4
2.5
LIST OF FIGURES
Page
Location Map for Source Area WP 14 ........................................... 2-2
Conceptual Hydrogeologic Model for WP14 and LF04 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Contaminant Release Mechanisms and Pathways for Exposure at WP 14 and LF04 . . . . . . . . 2-6
-------
2.3-1
2.3-2
2.3-3
2.3-4
2.3-5
2.3-6
2.3-7
2.4-1
2.5-1
LIST OF TABLES
Page
Summary of Groundwater Analytical Results for Source WP14,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Summary of Surface Soil Analytical Results for Source WP 14,
Elmendorf AFB, AK ........... ..................................... . '."" . ..2-10
Summary of Subsurface Soil Analytical Results for Source WP 14,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Summary Statistics for Background USGS Groundwater Analytical Data,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14
Exposure Assumptions for Evaluation of Carcinogenic Risk and Non-carcinogenic
Hazard Indices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16
Summary of Human Health Risks at WP14, Elmendorf AFB, AK .................. . . . 2-18
Summary of Contaminants of Concern at WP14, Elmendorf AFB, AK .................2-21
Costs and Time to Cleanup for Groundwater Alternatives at WPI4/LF04 South,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-25
Identification of Chemical-Specific ARARs and Remediation Goals, WP 14/LF04 South,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-32
ii
-------
Section 2.0
SOURCE WP14
The following subsections present the physical description, land use, groundwater use,
and hydrogeology of WP 14. The identification of activities which led to the current contamination at
\VP 14 is also included. The discussion of the regulatory and enforcement history of WP 14, the role of
the response action at WP 14, and community participation in the response action are included in the
general au 6 discussion in Section 1.0. '
2.1
Site Description
Source WP 14 (POL Sludge Disposal Site No. I), located a few hundred feet to the east
of Source LF04 (Figure 1.1-2), consists of an area approximately 400 feet by 300 feet, that was used
from 1964 to 1968 to dispose of sludge generated from POL tank cleanout operations. The area was also
used to weather fuel filters and pads left on the ground surface. The source area was closed with natural
soil cover. Figure 2.1-1 depicts the general layout of Source WP14.
This source area is located at an elevation of approximately 200 feet above mean sea
level (msl). The terrain at this source area slopes slightly to the west and surface drainage takes place in
the general direction of Knik Arm. The ground surface has been altered by construction activities and is
currently covered by low alder growth. Active and inactive underground fuel pipelines run through this
site. Scattered metallic debris (heavy equipment parts) is present on the southern portion of the source
area.
2.1.1
Land Use
The land use designation for WPI4 is open space in the Base Comprehensive Plan.
There are no known historic buildings, archeological sites, wetlands, floodplains, or rare or endangered
species at WP14.
2.1.2
HydrQgeology and Groundwater Use
This section describes the specific hydrogeology and groundwater use at Sources WPl4
and LF04. The discussion of the hydrogeologic settings at So'urces WPI4 and LF04 have been combined
because of their close proximity on the Elmendorf Moraine. The regional geology and hydrogeology at
Elmendorf AFB is discussed in Section 1.0. A more detailed discussion of the geology and
hydrogeology ofOU 6 is presented in the au 6 RIfFS Report (USAF, 1996b).
Sources LF04 and WP 14 are located on the Elmendorf Moraine, which overlies the
Bootlegger Cove Formation. The moraine deposits consist of predominantly clay-rich sections
containing discontinuous lenses of sand and gravel. The hydrogeology of the moraine deposits at Source
LF04 and WPI4 appears to be complex and highly dependent upon the lithology, porosity, and lateral
extent of the water bearing zones. What can be considered a shallow unconfined aquifer from a.regional
point of view was determined to be a series of perched aquifers at varied depth intervals. The series of
aquifers are depicted in the hydrogeologic conceptual model presented as Figure 2.1-2.
Three distinctive aquifer units were identified in the WP14/LF04 area. Groundwater
flow in the uppermost aquifer is predominantly to the west and steepens as the aquifer approaches the
bluff. The groundwater gradient of the first aquifer is approximately 325 feet per mile in the east, but
steepens to about 700 feet per mile to the west. At WP14, the depth to this first aquifer ranges from
approximately 10 to 40 feet bgs. The aquifer is slightly deeper at LF04. In the second aquifer,
January 1997
2-1
OU 6 ROD, Final
-------
o
C
0\
"
o
~o
."
S'
~
\ \ .
", (
\ \ \
\ \ \
\ \ \
\ \ \ I
\\ \. SOURCE WP14~ /---:.:-::=
,\ \ //--
\\ \ / ~£~0/'-'----
\ \ \ / ."
,I I / ~ '
\' 'Norlh /.. -.~ /'~t$,/
\ \ .. ~,./ I~,.'
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\ \ /. ,/'.,/, '
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" , .,' ". / / . c-.~
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',' ' .' .'/ / / J "
...."" .' .' / / /" . '"
~.... '" .'.'" / / "
, , V " / ' / ,
....(~'/ // "
/-;~-('.:.:~/ ", =:? ----
, '/ ',~ ':-5~-
",/~ "'~~~.. ~~~~~~\~;;---- -----.
",/ ',',,,- ~~''::-'''-G'----
. ,'.. ~~.~- ---
,'/' '.:::~ --01'-;:::'- .-- -- --
, " " ~. --- -.... '
.' ,. ",..~ ~'''!:-:---- --- ...-
, . ..... '= .. -~~~:..-- ---
.,' ,/ ' -"""":':~.::;.---' ------ .
) ......... ---
,-' ,,~/ ..I."'''''''' ------
.' ,"I' ~_...- -,----
.' ,'/ ,.",.~ ....-
.", ,.'// . ",..,.....- - - - ---
.' ,,' I ...'"" ---
,,' .,' I .....~ - - --
.,' ,", _.~ -----
,,' I ...-;...:"- --
.~",,,,,,',. ........,.....-;....."'" "....-"'-
T \ '-.""''''' y'" "....
.,'\~.V'" --,----
.,' /" /
ELMENDORF AFB
LEGEND
_._.- POL Lines
o
SCALE
50
100
-
~
i
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N
.
N
Boundary
/'>0
f\
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~
c:
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-
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Figure 2.1-1. Lo~n Map for Source Area WP14
-------
.....
III
::I
C
III
.:<
\0
\0
-.I
tV
I
W
o
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~
o
5'
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rWP14
/- LF04
//
./
( . 7 Per~hed Aquifers (sand and silt,"'-----"" '="" ------ Ii y/
" ~ lyp~cally 10-20 feet thick and ~:/.~ ~'
~~~~o~:~:e:el::nf~~~n:n:I:;'~:~~~~L: -. .. ...-
. . TYPically 20-40 feet thick 'J'
Second AquIfer .
Unconfined Aquife ? (sand)
Typically 10-15 f et of
saturated thickne sand
5-20 feet below the
beach surface.
... Tidal F'lat. ...
...
...
...
...
..
Sandy Beach
...
...
...
--./Sea level
... ...
~
." ~'\'«'
~~''''
...
'.
..
...
~
Legend
oD
01
on
C!
'"
o
..,
'"
N
o
'"
) Groundwater Flow
Figure 2.1-2. Conceptual Hydrogeologic Model for WP14 and LF04
-------
groundwater flow remains primarily to the west. The calculated groundwater gradient in the second
aquifer is approximately 100 feet per mile.
The second aquifer is bounded by the bluff where LF04 overlooks the Knik Ann and
partia!ly discharges as seeps along the bluff face. Seeps were observed at about 90 to 110 feet above sea
level in the bluff above the Knik Ann. The elevation of these seeps appears to be controlled by the
presence of a clay layer which could coincide with the top of the Bootlegger Cove Fonnation. The
aquifer occurs at a depth of about 70 feet bgs at WPI4, and from about 70-110 feet bgs at LF04. The
first and second aquifers appear to communicate in a mixing zone located roughly along the eastern
boundary of LF04.
The third groundwater aquifer at LF04 is at or near the beach level (Figure 2.1-2). This
aquifer was below the deepest depth bored to and therefore was not encountered during drilling at WP14.
Groundwater movement in the third aquifer is west to the Knik Ann. Gradients along the beach and
lower bluff face are relatively steep, at approximately 530 feet per mile. Groundwater seeps observed at
the base of the bluff appear to discharge water from the water-sorted aquifer at the base of the bluff. The
second aquifer also communicates with the beach level aquifer in a separate mixing zone.
The presence of mixing zones between the various aquifers allows for vertical hydraulic
connection between the three different aquifers in WPI4/LF04. Both of these mixing zones trend
roughly perpendicular to groundwater flow. The estimated hydraulic conductivity for this area ranges
from 1.12E-3 to 3.59E-S em/see in the various perched aquifers.
The groundwater in the shallow aquifer on base is not used for any purpose. Its future
use, even if the aquifer was uncontaminated, is generally limited because of the higher yield of the
deeper confined aquifer underlying the Bootlegger Cove Clay. In the vicinity ofWP14, the fine-grained
nature of the perched aquifer materials, and the laterally discontinuous nature of the perched aquifer
lenses, would make these aquifers wholly unsuitable as drinking water supply aquifers. Groundwater in
the deep aquifer on base is unaffected by contamination at WP14 or LF04, and remains as an alternate
water supply source. '
2.2
Site "isto.,. and Enforcement Activities
The following section identifies the activities which led to the current contamination at
WP14. The regulatory and enforcement history for WP14 is included in the general discussion presented
for au 6 in Section 1.0, as are the discussions of the role of the response action and the community
participation in the response.
Identification of Activities Leading to tbe Current Contamination at WP14
The contaminants identified in the groundwater at WP14 include primarily fuel-related
species, solvents, and metals. Fuel-related constituents and metals were also the most commonly
. occurring contaminants in the soil.
2.2.1
Among the sources of contamination identified at WP 14, the most obvious is the
disposal of POL sludge. Residual fuels and solvents were made available to leach into the soil and
groundwater as a result of the disposal of tank sludge and the weathering of fuel filters and pads in the
area. This activity is likely responsible for most of the surface soil contamination present at the site.
Second, abandoned and active POL lines that run through the source area in a northeastwardly direction
from Source LF04 (southwest) to Operable Unit 2 Source ST41 (northeast) were identified
OU 6 ROD, Final
2-4
January 1997
-------
(Figure 2.1-1). During the 1994 RI, an additional abandoned POL line was located. This line trends
approximately west to east through the southern portion of Source WP 14 between Sources LF04 and
ST41 (Figure 2.1-1). Other POL facilities such as valve pits, were identified at WPI4 in close proximity
to contaminated soil areas. The POL sources are likely contributors to the fuel-related contamination
present. This determination was made because subsurface soil contamination appears to be oriented in
relation to the fuel pipelines at the site, suggesting leaks from the lines as the probable contaminant
source. Groundwater contamination af WP 14 also appears to emanate from the vicinity of the two
inactive POL lines. Removal of these inactive POL lines is currently being planned under the UST
program. A schematic of the potential migration and exposure pathways for fuels and solvents through
the soil and into the groundwater is presented in Figure 2.2-1 for Sources WPI4 and LF04, since they are
in such close proximity.
Contaminated soil zones lying above the water table represent a "smear zone" of
contamination resulting from fuel and solvent constituents that migrated to a higher water table and were
left in the vadose zone as the water table declined. This smearing of contamination may occur between
seasons as the water table elevation changes. Downward percolation of groundwater through
contaminated soils at WP14 can also act as a contaminant source for the shallow aquifer.
Prior to the RI conducted at WP 14 in 1994, WP 14 had been addressed under the
following studies:
.
IRP Phase I/II Records Search and Statement of Work (Engineering-Science, 1983);
.
IRP Phase II Stage 3 Work Plan (Harding Lawson, 1988);
.
. Resource Conservation and Recovery Act (RCRA) Facility Assessment Report (ADEC,
1988); and
.
IRP Phase III, Stages 3 and 4, Remediallnvestigation/Feasibility Study (Black and Veatch,
1990).
The active POL line at WP14 has been tested and detennined to be sound. Both inactive
POL lines were reportedly drained prior to being abandoned in sections. The weathering and disposal of
POL sludge has been discontinued at WP I 4 since 1968.
2.3
Site Contamination. Risks. and Areas Requiring Response Actions
This section identifies the areas which were investigated, and those that require remedial
action. These areas were chosen based on the risk that contaminants pose to human health and the
environment. The basis of this analysis is the data collected during the RI which identified the nature
and extent of contamination at WP 14.
2.3.1
Nature and Extent of Contamination
During the RI, samples of soil and groundwater were collected and analyzed. Significant
levels of contaminants were detected in both the soil and groundwater at WP14. These contaminants
include fuels and fuel constituents, metals, and semi-volatile organic compounds (SVOCs). The
contamination present at WPI4 is associated with percolation of contaminants through the soil to the
groundwater, transport of dissolved contaminants with the groundwater, and volatilization of
contaminants. These transport mechanisms are pictorially represented for WP 14 in Figure 2.2- 1.
January 1997
2-5
au 6 ROD, Final
-------
o
c:
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~
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p
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5'
!!.
I'-.)
I
0\
....
~
c
~
-
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\0
,--.1
~
Sludge Disposal Site
Weathering of fuel
FII'", ..d P.d, ~
-~- ,
Legend
~{;}}J Residual Contaminolion
~ Dissolved Phase Contamination
- LNAPLS
~ WP14- POL Sludge
Disposal Site No, 1
, /" LF'04- Knik Arm Bluff Landfill
/ /~
/
onstructlon Debris, Old Cars,
Unknown' Quantity of Drums 01
Spent Solvents
Groundwater
Seep
~
y Seasonal High
Water Level
Seasonal Low
Y Water Level
(
. ""'" 'l;Wt.~~ I
Unconfined Aquif r. (sand)
Typically 10-,15 eel Of~
saturated thlckn ss and
5- 20 feet be the
beach sur e.
Sea Level
~ower Confining Unit
Oo!legger Cove Cia
TYPically about 50 r
outcro . eel
pplng on beach'
Confined A '
'Up t 55 qUlfer? (sand)
o 0 feet thick.
.0
a>
.,;
,..:
...
"
o
N
~
Figure 2.2-1. Contaminant Release Mechanisms and Pathways for Exposure at WP14 and LF04
~
-------
Tables 2.3-1 through 2.3-3 list the frequency of occurrence and maximum concentrations
of all constituents which were detected during the RJ in groundwater and soil. The tables do not include
results below the detection limit. The Maximum Contaminant Levels (MCLs) for groundwater and the
Alaska Cleanup Matrix (ACM) guidelines for soil are also listed on the tables for all constituents.
Results are separated between "indicator parameters" and "contaminant parameters." Indicator
parameters primarily include metals classified as nutrients, and non-speciated fuel constituents such as
unidentified diesel range organics (UDRO) which are unsuitable for use in a risk assessment. Indicator
parameters are typically not hazardous constituents but are important for determining general water
quality, sustaining growth of microbial cultures, and interpreting results of other analyses. A detailed
discussion of the determination of the contaminants ofconcem (COCs) for WP14 is presented in
Section 2.3.3.
Groundwater Contamination at WP14
The predom inant type of groundwater contamination detected at WP 14 is benzene,
toluene, ethylbenzene and xylene (BTEX) constituents and fuels. The highest BTEX concentrations are
found in the sample from MW-12 (Table 2.3-1). Benzene was detected at a maximum concentrations of
. 1390 /-LgIL in a sample from that well. BTEX constituents were detected in samples from every well at
WPI4. Maximum weathered fuel constituents were detected in samples from MW-12, MW-46 and
MW -06. Additionally, less than 1 inch offree phase floating product was detected at MW -12 during
field testing in 1995. .
. Low levels of chlorinated solvents, including a maximum detection of 2.45 /-LgfL in a
sample from MW-12 were also detected. Similar low levels of solvents have been detected in numerous
monitoring wells on base at other sites within OU 6 and at other OUs. SVOCs were also detected in the
groundwater at WP14, with the maximum detection occurring in a sample from MW-12 at
4130 /-LgfL bis(2-ethylhexyl) phthalate. This elevated concentration is believed to be the result of
degradation of the polyvinyl chloride (PVC) well casing in the presence of elevated levels of fuel
constituents, rather than being the result of improper waste disposal activities at WP14.
Numerous metals were also detected in the groundwater at WP 14. These include
relatively low concentrations of barium, beryllium, cadmium, chromium, cobalt, copper, manganese,
nickel, vanadium, and zinc (Table 2.3-1). In the evaluation of the metals concentration at WP14, a
comparison to background metals concentrations was conducted. Background metals concentrations in
groundwater were collected by the U.S. Geological Survey (USGS) in the Anchorage Bowl area and
compiled in the Elmendorf Air Force Base, Alaska, Basewide Background Sampling Report
(USAF, 1993). These metals data have been used historically at Elmendorf AFB for comparison with
on-site groundwater metals concentrations. Confidence intervals of the USGS data for a given metal
were compared with confidence intervals for the WP14 analytical results for the same analyte. If the
confidence intervals of the two means overlapped, the two means were considered not to be different and
the particular metal was removed from consideration as a COCo Based on this evaluation, all metals in
groundwater at WP 14 were determined to be at or near background concentrations. The summary
statistics for the USGS data, including the upper confidence limit concentrations used for these
comparisons, are presented in Table 2.3-4.
Soil Contamination at WP14
Soil data from WP14 were evaluated based upon surface and subsurface contaminant
occurrences. Surface soils include all soils collected from depths shallower than 3 feet bgs. Subsurface
soils are those collected from below 3 feet. Tables 2.3-2 and 2.3-3 list the sample depths, maximum
concentrations, locations, and guidelines associated with the ACM for non-UST soil for all contaminant
January 1997
2-7
OU 6 ROD, Final
-------
Table 2.3-1
Summary of Groundwater Analytical Results for Source WP14
Elmendorf AFB, AK
Frequency of Location of
~Ietbod Analyte MCLI Maximum Detections Maximum
(units) Result Total Hirst
Total Samples Result
Indicator Parameters
$W8015ME (jJgIL) Unidenlified organics [UDRO/ .. 2310 9/12 MW.06
5W8015MP (p.gIL) Unidenlified organics [UGRO/ .. 119000 b 10/12 MW-12
Xylene (Iolal) 10,000 7080 12/12 MW-12
$W60 I 0, Total (mgIL) Aluminum - 31.1 7/12 MW-12
Calcium - 109 12112 MW-13
Iron -- 52.5 12/12 MW.12
Magnesium - 30.8 12/12 MW46
Potassium -- 5.15 12/12 MW-12
Sodium -- 9.31 12/12 MW46
$W6010, Dissolved (mgIL) Aluminum -- 0.0704 B 1/2 MW-12
Calcium -- 32.7 2/2 MW-12
Iron - 0.0606 B 2/2 MW-12
Magnesium - 8.4 212 MW.12
Potassium -- 1.57 212 MW-12
Sodium - 4.41 212 MW.12
Contaminant Paramders
SW8015ME (jJgIL) let fuel (JP-4) -- 554000 3112 MW-12
5W801 5MP (jJgIl) Gasoline -- 167 1/12 MW-15
5W8260 (jJgIl) Acetone .- 24.3 b 12/12 MW-06
Benzene 5 1390 12/12 MW-46
2-Butanone(MEK) -- 18.6 F 3/12 MW.12
Chloroethane .. 0.48 3112 MW-46
Chloroform 100 0.25 2/12 MW.12
Chloromethane - 3.2 12/12 MW-15
1,l-Dichloroethane -- 1.04 2/12 MW-12
1,l-Dichloroethcne 7 0.29 1/12 MW-12
1,2-Dichloroethane 5 2.45 5112: MW-12
Ethylbcnzcne 700 1410 12/12 MW.12
2-Heunone -- 2.61 1/12 MW-15
Methylene chloride 5 3.9 B 8/12 MW-06
4-Methyl-2-pcntanone(MIBK) - 3.04 F 5/12 MW.12
Toluene 1000 3190 12/12 MW-12
1,1,1- Trichloroethane 200 0.56 1/12 MW.12
Trich1oroethene 5 0.8 1/12 MW.12
m&:p-Xylene -- 4360 12/12 MW-12
o-Xylene -- 1480 12/12 MW.12
$W8270 (ligIL) Benzoic acid - 37.2 1/12 MW-06
DimethylphthaJate - 110 5/12 MW-12
Di-n~lVlnhthalate - 49.6 1112 MW-12
OU 6 ROD, Final
2-8
January 1997
-------
Table 2.3-1
(Continued)
Frequency of location of
Method Muimum Detections
(units) Analytc MCL' Result Total Hitsl Mnimum
Total Samples Result
SW8270 (j.ag!L) bis(2. Ethylhexy I )phthalate 6 4130 3112 MW.12
(continued) 2-Mclhylnaphthalene .. 630 4/12 MW.12
Naphthalene - 384 4/12 MW.12
5W6010, Total (mg/L) Barium 2 0.241 12/12 MW-12
Beryllium 0.004 0.00212 B 7/12 MW-46
Cadmium 0.005 0.00715 3112 MW-46
Chromium 0.1 0.102 2/12 MW-12
Cobalt - 0.0237 7/12 MW-12
Copper 1.3) 0.11 2/12 MW-12
Manganese - 6.45 12/12 MW.06
Nickel 0.1 0.0934 2/12 MW-12
Vanadium .- 0.091 3/12 MW.12
Zinc - 0.246 9/12 MW-12
SW7060, TOlal (mg/L) Arsenic 0.05 0.038 2/12 MW-12
SW7421, Total (mg/L) Lead 0.0151 0.648 2/12 MW-12
SW6010, Dissolved (mg/L) Barium 2 0.0254 212 MW-12
Manganese - 5.27 212 MW-12
Zinc -. 5.27 212 MW-12
5W7060, Dissolved (mg/L) Arsenic 0.05 0.00337 1/2 MW-12
SW7421, Dissolved (mg/L) Lead 0.015) 0.0317 212 MW-12
I Muimum contaminant level (MCL); 40 CFR ~ 141.61 for Federal MCLs, and 18 MC 80.070 for State MCLs. Federal and State
MCLs arc identical for the listed constiruentS. .
: Frequency .hitS. calculation docs nol include one or more results removed from the data set because they did not meet QNQC criteria.
Total sample count includes all samples analyzed for the indicated parameter.
, From 40 CFR, Section 141.1 I for inorganics and Section 141.12 for organics (effective I July 1991); however, the lead level is effective
only until 7 December 1992. There is no longer an MCL for lead or copper (56 Federal Rel!ister 26460, June 7, 1991); however, there is
an action level of 0.01 5 mg/L for lead and 1.3 mg/L for copper.
b . Due 10 high concentrations of other target compounds in the sample, or to interference by non-target analytes, the sample could not
be run at a dilution faclor of one. The nagged analyte concentration is less than the blank UTL times the sample dilution factor.
. Sample concentration was less than or equal to the blank UTl.
- Co-elulion or interference was suspected.
B
F
January 1997
2-9
OU 6 ROD, Final
-------
Table 2.3-2
Summary of Surface Soil Analytical Results for Source WP14
Elmendorf AFB, AK
Sackgrouad Frequeucy or Lacalioa of
Metbod Aaalyte ACM Upper Maximum Detectlou Mnimam
(uaits) Toleraace Result total bits!
Limit to181 samDies Result
ladicator Parameten
SW9045 (pH unilS) pH - - 6.44 212 SS-050
D2216 (percent) Percent moiSNre - - 36.4 24124 SB-47
SW8015~[E(mWka) Unidentified orlUlllics rUDROl 1000 - 555 24124 SB-04
SW80IS~(mWka) Unidentified oraanics rUGROl 500 - 2.78 9124 SS-057
SW60IO (mglkg) Aluminum - 3118396 28900 24124 SB-14
Calcium - 8013.23 11100 24/24 MW-12
Iron - 43192.35 38800 24/24 SB-14
Magnesium - 10904.10 10500 24/24 SB-14
Potassium - 845.75 1680 24/24 SB-14
Sodium - 427.05 336 24/24 MW-12
Coatamiaaat Parameten
SW8015~ (jiglkg) Benzene 500 - 12.18 3/24 SS-60
Ethvlbenzene 50000 - 119 2124 MW-06
Gasoline 500000 - 9230 1/24 SS-060
Toluene 50000 - 75.4 8/24 SS-58
Xylene Hotal) 50000 - 113 7/24 SS-060
SW8240 (jiglkg)' Acelone - - 48 B 20/24' SS-05S
2.Butanone(MEK) - - 35.9 14/24 SS-054
Chlororonn - - 144 4/24 MW-06
Methylene chloride - - 3.82 B 3/24 SB-08
m &. p-Xylene 50000 - 68.2 2124 MW-06
o-Xylene 50000 - 29.3 2124 MW-06
SW8270 (jiS/kg) bis(2-EthYlhexvnDhthalale - - 0.698 6/24 SS-056
2-Methvlnaphthalene - - 0.785 312.. SS-oS7
2-Methvlphenol (o-cresol) - - 0.0951 2124 MW-06
Phenol - - 0.0262 B 1/24 MW-06
SW6010 (mglkg) Antimony - NA 9.67 5124 SS-049
Barium - 196.4S 350 24/24 S8-04
Bervllium - 0.76 0.615 24124 SB-14
Chromium - 48.44 47.3 24/24 S8-14
Cobalt - 19.52 16.5 24/24 S8-14
Copper - 31.67 55.! 24124 MW-06
MaRitanese - 929.98 881 24124 S8-o9
Molvbdenum - NA 2.12 18/24 SS-oS4
Nickel 5068 41.6 24/24 SB-14
2-10
January 1997
au 6 ROD, Final
-------
Table 2.3-2
(Continued)
Backirouud Frequeucy or LocatioD or
Metbod Aaalyte ACM Upper Maximum DetfCtioD Maximum
(uaits) ToleraDce Resu It total bits!
Limit total sa moles Resalt
SW60IO (mglkg) Selenium - 0.54 15.4 14/24 SB..Q7
cant Silver - 1.68 0.728 1/24 SB-14
Vanadium - 101.64 88.9 24/24 SS..QS4
Zinc - 90.01 75.1 24/24 SS..QS4
SW7060 (m2lkR) Arsenic - 13.27 15.5 24/24 SS..QS4
SW742 I (mRlb:) Lead - 10.69 18.6 24/24 SB-04
'Frequency "hits" calculation docs not include one or more results removed ftom the data set because they did not meet QNQC criteria. '
TOlJIlsample count includes all samples analyzed for the indicated parameter.
ACM - Alaska Cleanup Matrix. Level C.
B . Sample concentration was less than or equal to the blanklITL.
NA - Not applicable.
X - The recoveries of one or more of the intemal standards were outside the applicable acceptance criteria. The X-flag indicates which
compounds were quantitated using the affected internal standard(s).
January 1997
2-11
OU 6 ROD, Final
-------
Table 2.3-3
Summary of Subsurface Soil Analytical Results for Source WP14
Elmendorf AFB, AK
Background Depth of Frequency of Location of
Metbod ACM Upper Mllimum Detection
(units) Analytt Guideline' Tolerance Result Mllimam Total Hits! Muimum
Limit Result (R) Total Samples Result
Indicator Parameters
SW9045 (pH unilS) pH eo -- 8.53 22 3/3 5B-14
02216 (percent) Percent moisture - -- 29.3 7 66/66 5B-47
SW8015ME Unidentified organics 1000 -. 291 8 26/31 5B-03
(mglkg) (UDRO)
SW8015MP Unidentified organics 500 -- 6670 17 20m MW-06
(mglkg) [UGRO)
SW6010 (mglkg) Aluminum -- 18116.77 29800 8 31131 5B-03
Calcium - 10264.39 17600 34 31131 MW-15
Iron - 38483.64 38700 8 31131 58-03
Magnesium - 14784.34 14000 42 31/31 58-14
POlassium -- 1114.35 2740 8 31/31 58-03
Sodium - 365.59 871 42 31/31 5B-14
Contaminant Parametersl..
5W8015M Diesel 1000 -- 135E 14 4/31 58-09
(mglkg) Jet fuel (lP-4) 1000 -- 2050 17 1/31 MW-12
5W8015MP Benzene 5001 -- 1830 P 17 9135 MW-06
(l1g1kg) .- 1 -
Ethylbenzene - 22200 22 11135 MW-12
Gasoline 500000 -- 3140000 17 4/35 MW-12
Toluene - 1 -- 39700 17 13/35 MW-12
Xylene (Iotal) _I -- 93200 22 16/35 MW-12
5W8240 (l1g!kg) Acelone eo -- 367 14 28/35 ' 58-09
2-Butanone(MEK) -- -- 72.1 14 25/35 I 5B-09
Chloroform eo -- 26.4 12 5/35 MW -06
Methylene chloride -- - 23.6 12 12/35 58-07
4-Methyl-2-pentanone(MIBK) -- - 22.3 10.5 3/35 58-01
m & p-Xylene -- 1 -- 99400 17 9/35 MW-12
o-Xylene -- 1 -- 1730 17 8/35 MW-12
SW8270 (mglkg) 8enzo(a)anthracene -- - 0.0202 F 32 1131 58-14
Chrysene -- -- 0.0342 34 3/31 S8-14
Dibenzofuran -- - 0.0215 42 1/31 58-04
Di-n-octylphthalate eo -- 0.285 7 2/31 58-47
bi s(2 -Ethy Ihexy I)phthalate - -- 0.568 7 4/31 58-47
Fluorene - -- 0.0235 34 1/31 MW-15
2 -Melhylnaphthalene -- - 1.66 14 14/31 5B-09
Naphthalene - -- 0.277 22 9131 58-07
Phenanthrene -- -- 0.0952 34 5/31 SB-14
2-12
January 1997
OU 6 ROD, Final
-------
Table 2.3-3
(Continued)
Background Depth of Frequency of Location of
Method ACM Upper Maximum Detection
(units) Analyte Guideline' Tolerance Result Maximum Total RiuJ Mnimum
Umit Ruult (ft) Total Samples Result
SW6010 (mglkg) Antimony - NA 7.42 35.5 8131 MW-05
Barium - 95.93 141 8 31/31 5B-03
Beryllium - 0.64 0.65 8 31131 5B-03
Chromium -- 76.94 46.1 8 31/31 SB-03
Cobalt - 17.62 17.3 11 31/31 5B-01
Copper - 59.84 57.8 7 31/31 5B-09
Manganese - 709.45 822 11 31131 5B-Ol
Molybdenum - NA 1.95 42 28131 5B-04
Nickel - 71.79 44.9 11 31/31 5B'() 1
Selenium - 0.48 16.7 8 11131 5B-04
5ilver - 1.06 0.716 34 6/31 MW-15
Thallium -- NA 5.7 34 1/31 MW-\5
Vanadium -- 66.16 88.4 8 31131 5B-03
Zinc - 76.17 89.4 II 31131 58-01
5W7060 (mg/kg) Arsenic - 9.31 15.8 34 30131 SB-14
SW7421 (mglkg) Lead - 10.13 22.85 8 31131 58-03
I Alaska Cleanup Mallix (ACM) Level C; 18 AAC 78.315.
J The AC~I Level C guideline for benzene, toluene. ethylbenzene. and xylenes (BTEX) combined is 50,000 ~glkg.
, Frequency "hits" calculation docs not include one or more results removed from the data set because they did not meet QAlQC criteria. Total sample count
includes all samples analyzed for the indicated parameter.
E . Anillyte exceeded calibration range, but did not saturate the detector; therefore. data is usable.
F - Co-elution or interference was suspected.
NA - Not applicable.
P - Analyte quanlitation not confirmed. Results from primary and secondary GC columns differ by greater than a factor of three.
S - . Metal concentration reponed was obtained using the method of standard additions.
2-13
OU 6 ROD, Final
January 1997
-------
Table 2.3-4
Summary Statistics for Background USGS.Groundwater Analytical Data
Elmendorf AFB, AK
Background Summary Statistics-, (mglL)
Analyte Method Hits Min. Max. Mean
Aluminum Unknown 0/1 NO NO NC
Antimony Unknown 21/28 NO 0.014 0.002
Antimony Unknown 21/28 NO 0.014 0.002
Arsenic Unknown 28/28 0.001 0.130 0.029
Arsenic Unknown 28/28 0.001 0.130 0.029
Barium NA NA NA NA NA
Beryllium Unknown 0/10 ND NO NC
Cadmium Unknown 2/28 NO 0.001 NC
Calcium NA NA NA NA NA
Chromium Unknown 27/28 NO 0.350 0.043
Cobalt NA NA NA NA NA
Copper Unknown 28/28 0.001 1.10 0.094
Cyanide NA NA NA NA NA
Lead Unknown 13/28 NO 0.300 0.028
Magnesium NA NA NA NA NA
Manganese Unknown 28/28 0.150 64.00 6.81
Mercury Unknown 14/2 1 NO 0.001 0.000
Molybdenum NA NA NA NA NA
Nickel Unknown 26/28 NO 1. 000. 0.093
Nitrate-Nitrite as N NA NA NA NA NA
Potassium NA NA NA NA NA
Selenium Unknown 0/10 NO NO NC
Silver Unknown 1/10 ND 0.001 NC
Thallium Unknown 0/10 NO NO NC
Vanadium NA NA NA NA NA
Zinc Unknown 25/28 NO 3.50 0.242
. Background obtained from USGS.
NA . No data available.
NC . Not calculated due to insufficient data.
ND . Not detected.
2-14
January 1997
OU 6 ROD, Final
.'"
-------
parameters in the surface and subsurface soil samples at WPI4. Results belo.w the detection limits are
not included in the analytical summary tables.
Organic contamination at WPI4 consists primarily of weathered residuals from fuels.
BTEX constituents were detected in both surface and subsurface soils. The levels in the subsurface soils
exceeded those of the surface soils, with the maximum BTEX occurrence being xylene at 93,200 J..tglkg
in a soil sample from the MW-12 pilot boring. The maximum fuel detection, for gasoline, also occurred
in a sample from the MW -12 boring. Low levels of other organics, such as chloroform and methylene
chloride were also detected in both surface and subsurface soils, as were low levels of SVOCs. The
SVOCs are believed to be weathered residuals from fuels. The discussion of soil COCs for WPI4 is
presented in Section 2.3.3.
Metals were also identified at WPI4, and were determined to be at or near background
concentrations. The background results used in the metals evaluation at WP14 are included in the soil
analytical tables (Tables 2.3-2 and 2.3-3). Background soil analytical data were collected in association
with the basewide background sampling effort (USAF, 1996b). During the background soil
investigation, 60 soil samples were collected from 14 soil borings drilled at background locations at the
base. The analytical results associated with these samples were pooled into surface and subsurface soil
results, and were used as the basis to conduct statistical comparisons with on-site results. With the
possible exception of lead as an additive in fuels, there are no known anthropogenic sources for the
metals detected at WPI4.
2.3.2
Risk Evaluation
Based on the concentrations of contaminants detected during the RI, human health and
environmental risk assessments were performed to determine if areas should be considered for remedial
action. A II concentrations of contaminants, including all contaminants of concern, whether exceeding
MCLs or ACM guidelines or not, were included in the risk assessments. The subsections below include
the general discussion of the human health and ecological risk .assessment procedures followed for OU 6.
As the procedures for each of the source areas within au 6 were identical, this discussion will be
referenced in the site specific sections for the other OU 6 source areas.
Human Health Risk Assessment (BRA)
By determining under what land use conditions people are potentially exposed to what
chemicals, for how long, and by what pathways of exposure, the cancer and noncancer risks were
determined in the RIIFS (USAF, 1996b).
Exposed Populations and Exposure Pathways -- Listed below are the four exposure
scenarios evaluated in the human health risk assessment. Details on the parameters used in the Health
Risk Assessment are shown on Table 2.3-5.
.
Future Residential: The HRA evaluated exposure of residents to contaminated shallow
soil through direct contact (incidental ingestion and dermal absorption) and inhalation of
dusts. Their exposure to shallow aquifer groundwaterthrough ingestion, inhalation
(showering), and dermal contact (showering) was also evaluated.
.
Construction (Trench) Worker: The HRA evaluated exposure of short term
construction workers to contaminated deep soil through direct contact (incidental
ingestion and dermal absorption) and inhalation of dusts.
2-15
OU 6 ROD, Final
January 1997
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Table 2.3-5
Exposure Assumptions' for Evaluation of Carcinogenic Risk and Non-carcinogenic Hazard Indices
Elmendorf AFB, AK
On-Site Residential Subsurface Visitor
Occupational or
Adult Child Trench Worker Adutt Child
Parameter RME RME RME RME RME
Body Weight (kg) 70' IS" 70' 70' 15'
Exposure Duration (yrs) 30' 6d I C 30 c 6c
Averaging time (carcinogens) (yrs) 70d NA 70 d 70 d 70d
Averaging time (noncarcinogens) (yrs) NA 6d 1 d 30d 6d
Total Inhalation rate (mJ/day) 20d 16. 20d 20d 16.
Soil Ingestion/Contact
Soil Ingestion Rate (mglday) 100' 200. 480' 100c 200.
Soil to Skin Adherence Factor (mglcm2) 1 r 1 r 1 r I r 1 r
Exposed Skin (cm2) 5000 b 3900 b 3160 r 5000 b 1900 b
Exposure Frequency (dayslyr) 185' 185' 40. 12. 12.
Water Use
Water Ingestion (Uday) .2. 0.7. NA I h I h
Indoor Inhalation Rate (m)/day) 15 . 12. NA NA NA
Exposure Frequency (dayslyr) 350. 350. NA 12h 12b
Skin Surface (em:) 23000 r 10,6~ r NA 820h 410h
Duration of Dermal Contact with Water 15 r 15 r NA 10h loh
(min)
I footnotes a.b and d.g refer to documents discussed in the Human Health Risk Assessment for OU 6 (USAF, 1996b).
. USEPA. 1991b.
. USEPA, 1991d.
, Assumption (USAF. 1996b).
. USEP A. 1989b.
. USEPA. 1989d.
I USEPA. 1992a.
. Bamack. 1994.
h Applies only to surface water seep exposure at Source LF04. Exposure to water was not evaluated as part of the visitor scenario at any other
source areas. .
NA . Not applicable.
au 6 ROD, Final
2-16
January 1997
-------
.
Visitor: The HRA evaluated exposure of an adult and child visitor to contaminated
shallow soil through direct contact (incidental ingestion and dermal absorption) and
inhalation of dusts. Exposure to seeps was also evaluated at applicable sites.
.
lead Evaluation: EXPQsure to lead in the soil was performed using the USEPA's
Uptake/Biokenetic Model for lead. This model provides a prediction of blood lead
,concentrations based on diet, inhalation, and soil/dust intake for children 0-7 years of
age.
Since WP 14 is not currently used residentially, a current residential risk scenario was not evaluated and
only current visitor and trench worker scenarios were applied. Even though the future land use at WPl4
is limited as specified in the Base Comprehensive Plan, thejUture residential risk scenario was evaluated
at WP 14 to obtain the most conservative risk information possible.
Exposure Assumptions - Risk can be calculated both for the average exposure and the
reasonable maximum exposure (RME) of the population. All chemicals detected during sampling were
evaluated as potential sources of cancer and noncancer health risks. In the case of metals, risks were
only calculated if the metals concentrations exceeded background concentrations. For RME exposures,
the statistically derived 95% Upper Confidence limit (UCL) of the mean concentrations was used to
calculate exposures. In instances where the 95% UCl concentration was greater than the maximum
concentration detected, the maximum was used as the receptor exposure concentration.
Using exposure levels and standard values for the toxicity of contaminants, excess
lifetime cancer risks (ElCRs), and hazard indices (HIs), were calculated to describe cancer and
noncancer risks, respectively. The ElCR is the additional chance that an individual exposed to site
contamination will develop cancer during hislher lifetime. It is expressed as a probability such as
I.OE-06 (one in a million). The HI estimates the likelihood that exposure to the contamination will cause
some negative health effect. An HI score above one indicates that some people exposed to the
contamination may experience at least one negative health effect.
ElCRs and HIs were calculated using Reference Doses (RIDs) and Cancer Slope Factors
(CSFs), which represent the relative potential of compounds to cause adverse noncancer and cancer
effects, respectively. Two sources of RIDs and CSFs were used for this assessment. The primary source
was the Integrated Risk Information System (IRIS) database, the USEP A repository of agency-wide
verified toxicity values. If a toxicity value was not available through IRIS, then the latest available
quarterly update of the Health Effects Assessment Summary Tables (HEAST) issued by the USEPA's
Office of Research and Development was used as a secondary source. For some chemicals detected at
OU 6, no toxicity value from IRIS or HEAST was available, and toxicity values were provided by the
USEPA Superfund Technical Support Center at the Environmental Criteria and Assessment Office in
Cincinnati.
Table 2.3,6 summarizes the carcinogenic and noncarcinogenic human health risks,
calculated for WP14. The risks are based on hypothetical exposure to soil and groundwater. The
shallow groundwater aquifer is not presently used, and will not be used in the future for supplying
potable or non-potable water. For carcinogenic soil risk, the calculated results for the future resident,
(RME), construction worker, and visitor are listed. Only the future resident scenario (RME) was used to
calculate carcinogenic groundwater risk. These risk values are also included in the table.
January 1997
2-17
OU 6 ROD, Final
-------
Table 2.3.6
Summary of Human Health Risks at WPI4
Elmendorf AFB, AK
Surface Soil (<3 feet) Subsurface Soil
Risk Chemical(s) Driving
Residential Visitor Trench Risk
Scenario. Scenariob Worker Scenario.
Soil Risk d
Carcinogenic 1.8E-05 1.0E-06 < 1.0E-06 Arsenic
. Non-Carcinogenic 2.75 0.14 NR Arsenic, Manganese
Groundwater Risk d
Carcinogenic 2.4E-03 NA NA Benzene,
bis 2-( ethylhexyl)plthalate,
1,2 - Dich loroethane,
1,I-Dichloroethene,
Toluene
Non-Carcinogenic 16.8 NA NA bis 2-(ethylhexyl)phthalate,
1,1- Dichloroethene,
Toluene
. Excess cancer risks conservatively assumed for 30 years of exposure (drinking groundwater, contact with soil, etc.) by future residents
(Reasonable Maximum Exposure).
. Excess cancer risks conservatively assumed for 30 years of exposure while visiting the site under current conditions.
< Excess cancer risks conservatively assumed for I year of exposure during on-site construction work (digging, etc.).
J Risks are calculated by using the 95% upper confidence limits (UCLs) for contaminants present unless the 95%UCL exceeded the maximum
concentration detected. in which case the maximum concentration was used. This represents a conservative estimate of the "worst case"
contamination.
NA . Not applicable.
NR . Significant risk not identified.
2-18
January 1997
au 6 ROD, Final
-------
Groundwater carcinogenic risk at WPI4 exceeded I.OE-03. Benzene is the predominant
risk driver, with four other constituents, including solvents, an SVOC, and toluene, as the other risk
contributors. Toluene is the primary contributor to the noncarcinogenic risk, which exceeded an
acceptable HI of 1.0 in the residential scenario (IU.-tE). Soil carcinogenic risk at WP 14 exceeded
I.OE-06 for the residential scenario, and is marginal for the visitor scenario. The noncarcinogenic risk
for RME soils also exceeded 1.0. Risk to trench workers from deep soil is at an acceptable level. All
soil risk was 100% attributable to metals contamination. The metals at WPI4 are believed to be at
background concentrations.
Ecological Risk Asseskment (ERA)
The ERA was performed to determine if the reported concentrations of chemicals or
calculated exposures to plants and wildlife at au 6 are likely to produce adverse effects. Ecological
effects were evaluated quantitatively by calculating Ecological Quotients (EQs). EQs are defined as the
ratio between measured concentrations or predicted exposures, and critical effects levels. If an EQ is less
than 1.0, the effect is unlikely to occur. Critical effects are defined in the selection of assessment and
measurement endpoints. Assessment endpoints are the general environmental resource or value that is
being protected. A measurement endpoint is a specific criterium that is used to evaluate the more
general assessment endpoint.
Elmendorf AFB contains 13,095 acres, approximately 4, I 00 of which are developed.
Twenty-nine types of terrestrial and aquatic vegetation have been reported on base, primarily in the
undeveloped portions, such as au 6. Mammal, bird and fish species are also common. No endangered
or threatened species of animals or plants reside, or frequents the base. However, the peregrine falcon, a
federally-listed endangered species, was identified as a low-frequency visitor during spring and fall
migration.
The ERA focused on evaluating potential impacts of the contamination on selected
indicator species: the moose, masked shrew, meadow vole, black-capped chickadee, merlin, and
peregrine falcon. The spotted sandpiper was also identified as an indicator species for evaluating
ecological risk on the beach. .
The ecological quotient (EQ) of 1.0 was exceeded for the black capped chickadee,
meadow vole, and shrew in soil at WP14 due to selenium concentrations. The highest EQs for selenium
were associated with the masked shrew and equaled 180. The seienium EQs for the black capped
chickadee and meadow vole were equal to or less than 3.3. None of the calculated EQs exceede~ 1.0 for
the moose, peregrine falcon, or merlin at WPI4. It should be noted that the graphite furnace method
(SW7740) was used to calculate selenium background UCLs, while the ICPES method (SW6010) was
used to analyze for selenium in soils at WP14. There is substantial uncertainty associated with the
results for concentrations near the detection limit for selenium associated with SW60 1 0 due to
interferences. Since the maximum selenium result in the soils at WPI4 was only approximately three
times the detection limit, and SW7740 data are not available, it is highly likely that the data used to
calculate the EQs for selenium at WPl4 are not representative of actual selenium concentrations, and
may be biased high. . Therefore, it appears that there is a low potential for ecological risk due to selenium
at this source area. No significant impacts to plants or animals warranting action were determined to be
present based on the results of the ERA.
Uncertainties Associated with the Risk Assessment
Risk assessments involve calculations based on a number of factors, some of which are
uncertain. The effects of the assumptions and the uncertainty factors may not be known. Usually, the
January 1997
2-19
au 6 ROD, Final
-------
effect is difficult to quantifynumerically, so the effect is discussed qualitatively. Some of the major
assumptions and uncertainty factors associated with the risk assessment are the following:
.
Existing concentrations are assumed to be the concentrations in the future. No reduction
through natural degradation and attenuation over time is taken into account (may
overestimate risk).
.
No increase through additional contamination is assumed (may underestimate risk).
.
The use of total rather than dissolved metals data for groundwater is problematic due to
the undefined contribution added by the particulate material added in the unfiltered
samples (may overestimate risk).
.
Potential degradation products of existing organic contaminants are not considered (may
overestimate or underestimate risk).
.
Potential effects on the indicator species are assumed to be representative of other
animals at OU 6 (may overestimate or underestimate risk).
Conclusions
The following subsections provide a discussion of the detennination ofCOCs for WP14;
the location and extent of contamination by COCs in excess of preliminary remediation goals; and a
summary statement about the risk to public health, welfare, or the environment if action is not taken at
WP14.
2.3.3
Contaminants of Concern
Constituents exceeding preliminary remediation goals (MCLs for groundwater or ACM
guidelines for soils) were identified in the Proposed Plan. COCs were developed from the results of the
risk assessment and by considering preliminary remediation goals. Each constituent having an individual
contribution of greater than 1.0E-06 carcinogenic (RME) risk, or an I-ll greater than 0.1 when the
cumulative HI for the site is greater than 1.0, was considered as a COC. In addition, any constituent
exceeding preliminary remediation goals (MCLs for groundwater or ACM guidelines for soil) was also
considered as a COe. The final COCs for WP14 are shown on Table 2.3-7, with the individual risk
contributed and basis for identifying the COC (risk or regulatory standard).
Three COCs were identified for groundwater at WP14: benzene, ethyl benzene, and
toluene (Table 2.3-7). These constituents contribute to a broad plume of contamination in the.
groundwater at WP14, depicted in Figure 2.3-1. The plume map is drawn based upon concentrations
exceeding 5 ,ugIL, which is the MCL for benzene. This map is combined with the contaminant plume
map for LF04, since the groundwater beneath these two source areas is interconnected, as discussed in
Section 2.1. The groundwater plume at WPI4 emanates from groundwater monitoring wells MW-46 and
MW -06, which were two of the principal wells contaminated with fuels identified in the nature and
extent of contamination discussion. Groundwater contamination from WPI4 represents an upgradient
source for the groundwater contamination at LF04. The combined plume from WP14 and LF04 is
estimated to contain 45.5 million gallons of fuel contaminated groundwater.
The Proposed Plan identified two additional groundwater constituents as exceeding
regulatory levels: bis(2-ethylhexyl)phthalate and cadmium. Bis(2-Ethylhexl)phthalate was not
2-20
January 1997
au 6 ROD, Final
-------
....
~
c
~
Table 2.3-7
Summary of Contaminants of Concern I at WPI4
Elmendorf AFB, AK
\0
\0
......
tV
I
tV
Chemical Maximum Maximum Cancer Maximum Hazard Basis for cac Remediation Basis for
Concentration Risk Index Goal Remediation Goal
Groundwater:
Benzene 1390 J!g/L 2.0E-03 -- Exceeds MCL; contributes 5 J!g/L MCL
to a risk> 1.0E-06
Elhylbenzene 1410 J!g/L u -- Exceeds MCL 700 J!g/L MCL
Toluene 3190 J!g/L -- 12 Exceeds MCL; contributes 1000 J!g/L MCL
to HI> 1
Shallow Soils (0-5 feet bgs): (No COCs for Shallow Soils)
Deep Soils (>5 feet bgs): (No COCs for Deep Soils)
I Cancer risk :t I.OE-06 or HI :t 0.1 forsoil or groundwater scenario with a tolal HI of:t 1.0; or concentrations found in excess of regulatory levels. If cancer risk or H[ did not exceed st~ndards. it
was marked as "-".
bgs - Below ground surface
COC - Contaminant of concern
MCL - Maximum Contaminant Level (40 CFR f 141.61 for Federal MCLs; [8 AAC 80.070 for State MCLs). Federal and State MCLs arc identical for the COCs.
o
c:::
0\
~
P
"'"
S.
~
-------
o
c:
0\
:::0
o
~o
'TI
S'
~
ORIGINAL LF04
BOUNDARY
\} ~
I: .
I"" - -
;- MIXING ZONE. .)-
/ ....)0
'I
? 'J,-
.........,0 .
""
WW-/)
tV
I
tV
tV
f
~
.*
i2'
~
. ,
. '-'. '"
I
I - .. - - u .-
I , .- -: '- - ~ :... _u ~ '-'-
," .~.._-
.. .'/ .... w,,-'o
.'/
.. .
SOURCE WP14
II t-.It,
. - _.
~, :\
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W"-Ol
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LF04 NORTH
AND BEACH
II'
;., \
r:~
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r~;J I. p .,':
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jl I .: !:! ; ~: 1.1.
! . . II I.
:" ..4~
'--- - - ---1-; ~ ~--.~\
..: :
_.;; :"",,_.-
.'
. !
-'-
/
/
ELMENDORF AFB
LEGEND
.. - W.. Loca~
: .. ,.. :
'1 -: =-
. I j
. .-"
/ ,II
r J I II
,., \.11
""-1, \~.\
- "IIW-U \ II
.. \ \)
.. - \ II
'. "
" \ \ \
\
\ '
\
\ \ \
, \ \
,.: SeeI>Ige lOCl~
.;b-'I MoaonaZ-
4ilU~ F""R..-~.Ad«..Hd..FS
I;>:: ..'
')"
\:.=.' SInNIZ- Soil eon_-
- - - - lF04 SoufI Bcuncl8ry
- - - - OngorIIIlF04 BcuncI8ry
- WPIC 80uncIIIy
- - - p......
- .. - InlIdUon Bound8Iy
Seal.
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.,.
.,
'.".
-
o
.
:100
~~
F...
-
\D
\D
~
Figure 2.3-1. Fuel Plume in the Groundwater at WP14ILF04 South
-------
identified as a COC in the ROD because detection of this compound can be associated with sampling in
the presence of fuel and not with historic land uses. Cadmium was not identified as a COC, because it
did not contribute to significant risk and only marginally exceeded th~ MCL in one of 12 samples.
Chromium levels in groundwater also marginally exceeded the MCL, but their concentrations were
determined to be statistically below background levels. Cadmium and chromium were also detected only
in the total metals analysis.
No COCs were identified for soils at WP 14. A cancer risk of 1.8E-OS was calculated for
soils at WPI4. This risk was within the acceptable risk range of I.OE-04 to I.OE-06. Furthermore, this
risk was attributable to metals in the soils which were determined to be comparable to background
concentrations.
As specified in the Proposed Plan, fuel constituents were detected in excess of ACM
Level B guidelines in both deep (greater than S feet bgs) and shallow (less than S feet bgs) soils. For
shallow soils, ORO exceeded ACM Level B. During preparation of the au 6 ROD, the ACM scoring
criteria were reexamined and consensus was reached between ADEC, USEPA, and USAF that ACM
Level C was more appropriate at WP 14. ACM Level C would be protective of human health and the
environment and is more stringent than the level being used at similar sites elsewhere. ORO
concentrations in the shallow soils at WP14 did not exceed ACM Level C; therefore, no COCs were
established for shallow soils.
The Proposed Plan also listed ORO, GRO, benzene, and BTEX as deep soil
contaminants that exceeded cleanup guidelines. A treatability study conducted at WP 14 in August 1996
determined that this contamination is in the smear zone. Because smear zone soil contamination is
believed to be the result of groundwater contaminants adhering to exposed soil particles during periods
where the water table is low, these contaminants are indistinguishable from groundwater contamination.
Therefore, smear zone contamination will be addressed as part of the groundwater remedy. Data
collected during the RI showed that there was no deeper soil contamination beneath the smear zone.
Thus, there are no COCs for deep soils at WP14.
Summary
Actual or threatened releases of hazardous substances from WP 14, if not addressed by
implementing the response action selected in this ROD, may present an imminent and substantial
endangerment to public health, welfare, or the environment.
2.4
Remedial Action Objectives. Alternatives. and Comparative Analysis for WP14
The following subsections discuss the remedial action objectives for WP14, and present
a description of the various alternatives which were evaluated to achieve those remedial objectives. The
results of the detailed comparison made between those alternatives are also presented.
Remedial Action Objectives
Specific remediation alternatives were developed and evaluated for the areas with
potential risk and for the areas that exceeded the preliminary remediation goals identified in Section
2.3.3. As previously discussed, the soil at WP14 does not have any COCs; therefore, RAOs were not
developed for WPI4 soils. The specific remedial action objective (RAO) for groundwater at WP14 is as
follows:
2.4.1
January 1997
2-23
OU 6 ROD, Final
-------
.
Prevent the ingestion, dermal contact, and inhalation of vapors from water from the
groundwater having benzene, ethylbenzene, and toluene in excess of MCLs and/or
resulting in a cancer risk greater than 1.0E-06 or Hazard Index greater than 1.0.
Groundwater Alternatives
As discussed in Section 2.3.3, the primary COCs for WP14 are fuel constituents in
groundwater. The four most promising groundwater alternatives (flGfI) were chosen on the basis of the
nine CERCLA criteria. These included no action (G I); long-term monitoring with institutional controls
and product recovery (G2); pump and treat with institutional controls and long-term monitoring (G3);
and high-vacuum extraction with institutional controls and long-term monitoring (G4). In addition to
addressing the contamination at WP 14, these alternatives would also address the bluff groundwater at
LF04 South (see Section 3.3). The COCs for LF04 South include fuel constituents and halogenated
volatile organic compounds (HVOCs).
2.4.2
Time to complete cleanup for biological alternatives was calculated using a two-
dimensional fate and transport model which considers biodegradation, retardation, advection, dispersion,
and adsorption/desorption. Cleanup times for each alternative are presented in the discussion below.
This model did not consider soil contamination as a continuing source of contamination to groundwater,
but it did consider retardation caused by contaminants adhering to soil particles. Degradation rates were
used to estimate the remediation time for fuel-contaminated smear zone soils. This time was factored
into the groundwater remediation times.
Except for the no action alternative, the cost of each alternative includes monitoring .of
groundwater for the estimated time period to complete cleanup, up to a maximum of 30 years, in
accordance with CERCLA guidance. Net present value cost was calculated using a 5% discount rate.
Costs estimates were calculated using the USAF Remedial Action Cost Engineering and Requirement
(RACER) system and have an accuracy of -30 to +50 percent.
The alternatives are as follows:
Alternative Gl: No Action
There are no costs associated with this alternative.
Evaluation of this alternative is required by CERCLA as a baseline reflecting current
conditions without any cleanup. This alternative is used for comparison with each of the other
alternatives. It does not take into consideration future events such as degradation and dispersion;
however, these processes are expected to occur. As a result, cleanup levels are expected to be achieved
within the same time frame as Alternative G2 (14 years for WP14/LF04 South). This alternative does
not include long-term monitoring, controls, or access restrictions; therefore, potential exposure pathways
would not be eliminated and future degradation would not be monitored. .
Alternatives G2: Long-term Monitoring witb Institutional Controls and Product
Recovery
Costs and time to cleanup for this alternative are presented in Table 2.4-1.
Groundwater would be remediated by natural processes (physical, chemical, and
biological) that reduce contaminant concentrations. Data have shown the presence of some dissolved
oxygen and nutrients in the groundwater beneath Elmendorf AFB; therefore, the assumption of
biodegradation ofCOCs is reasonable. This alternative includes semi-annual sampling of the
OU 6 ROD, Final
2-24
January 1997
-------
groundwater until cleanup levels are attained. Contaminants should degrade to regulatory levels within
14 years. Additionally, free phase floating product would be removed with a bailer during the
semi-annual sampling events. Free-phase product is expected to be found in insignificant amounts and
should not affect cleanup rates. Existing land use restrictions would be used to limit access to
contaminated groundwater. Land use restrictions are part of the Base Comprehensive Plan. These
controls would prohibit construction of groundwater wells for residential, industrial, or agricultural
purposes in the contaminated shallow aquifer. The USAF would continue to monitor groundwater
quality semi-annually until containment levels are below cleanup levels for two consecutive monitoring
events. If there is any indication that cleanup levels will not be attained, the remedial actions would be
reevaluated and additional action taken if necessary.
Table 2.4-1
Costs and Time to Cleanup for Groundwater Al(ernatives at WP14ILF04 Soutb
Elmendorf~,AJ{
Costs (Thousands of $) . Time to Cleanup
Alternative (years) .
Capital Annual O&M. Present Valueb
G2 1.71 46.5 462 14
G3 4620 257 7170 14
G4 2940 155 3150 1.4
. O&M = Operation and maintenance
b Present value discount rate = S%
Alternative G3: Pump and Treat witb Institutional Controls and Long-term
Monitoring
Costs and time to cleanup for this alternative are presented in Table 2.4-1. The
groundwater model used to calculate remediation time factors in degradation and dispersion of
contaminants as they migrate from the upgradient end of the plume to the extraction wells. The
remediation times for Alternatives G2 and G3 are identical because the contamination furthest
upgradient from the extraction wells will degrade and disperse before reaching the extraction wells.
In Alternative G3, groundwater extraction wells would be installed along the top of the
bluff to remove contaminated groundwater and free product as it traveled towards Knik Ann. Extracted
liquids would be piped to an oil/water separator where product would be separated from water. The
recovered product would be disposed of at the Defense Reutilization and Marketing Office (DRMO).
The water would be piped to an air stripping tower where an air stream would be used to volatilize
contaminants from the liquid to the vapor phase. The vapor phase would be discharged to the
atmosphere. The partially treated groundwater would be sent to a carbon adsorption system for
additional treatment. The treated groundwater would then be discharged to Knik Arm. This alternative
also includes land use restrictions and the monitoring program described in Alternative G2. When two
consecutive monitoring events indicate that contaminant levels are below cleanup levels, the pump and
treat system would be turned off. Semi-annual sampling would continue for one more year. The sample
results would be evaluated to detennine if the contaminant concentrations had stayed below cleanup
January 1997
2-25
OU 6 ROD, Final
.C
-------
levels. If so, the treatment system would be discontinued and no further action would be required. If
contamination concentrations had rebounded, the treatment system would be restarted.
Alternative G4: High-vacuum Extraction with Institutional Controls and
Long-term Monitoring
Costs and time to cleanup for this alternative are presented in Table 2.4-1.
In this alternative, extraction wells would be installed about 75 feet apart throughout the
entire affected area. High vacuum (about 20 to 28 inches of mercury) would be applied to these wells to
extract groundwater, floating product, and soil vapor at a fast rate. Reduced pressure and turbulence in
the extraction wells would cause some contaminants to volatilize into the vapor phase as the water is
extracted. The vapor phase would be discharged to the atmosphere. The liquid phase would flow to an
oil/water separator. Recovered hydrocarbons would be sent to the DRMO. The groundwater would then
be piped to a carbon adsorption unit for polishing before being discharged to Knik Arm. This alternative
also includes land use restrictions and the monitoring program described in Alternative G2. When two
consecutive monitoring events indicate that contaminant levels are below cleanup levels, the
high-vacuum extraction system would be turned off. Semi-annual sampling would continue for one
more year. 'The sample results would be evaluated to determine if the contaminant concentrations had
stayed below cleanup levels. If so, the treatment system would be discontinued and no further action
would be required. If contamination concentrations had rebounded, the treatment system would be
restarted.
Summary of Comparative Analysis of Groundwater Alternatives
The comparative analysis describes how each of the groundwater alternatives meet the
CERCLA evaluation criteria relative to each other.
2.4.3
Threshold Criteria
Threshold criteria are those that must be met for the alternative to be viable and relate
directly to the statutory determinations discussed in Section 2.5.1. This category includes two criteria:
overall protection of human health an~ the environment and compliance with ARARs.
Overall Protection of Human Health and the Environment-Alternatives G2, G3, and
G4 all meet this criterion since they each monitor the reduction of contaminants to acceptable levels
through active treatment or natural processes. Alternative G4 is considered to provide the most
protection (primarily by virtue of its comparatively short remediation time, 1.4 years), followed by
Alternatives G2 and G3 (14 years). Alternative GI (No Action) was the only alternative that failed to
meet this criterion. This failure was a result of the alternative not satisfying the RAOs nor complying
with ARARs. This alternative is therefore the least protective.
Compliance with ARARs-Alternatives G2, G3, and G4 each meet this criterion for
chemical-specific ARARs since each provide for the timely reduction of groundwater contaminants to
levels below ARARs. Alternative G4 would comply with chemical-specific ARARs sooner than the
other alternatives and is therefore considered the most compliant of the alternatives. Alternatives G2 and
G3 would take longer to remediate in-situ contamination concentrations down to drinking water
standards (i.e., MCLs). Alternatives G3 and G4 are preferred because they comply with ARARs through
active treatment of the groundwater. Alternative G I (No Action) failed to meet this criterion because it
does not include a sampling program which w~uld monitor contaminant concentrations in the future.
Therefore, it would not be known if and when contaminant concentrations attenuated to drinking water
OU 6 ROD, Final
2-26
January 1997
-------
standards (i.e., MCLs). Alternatives G2, G3, and G4 all contained a sampling program that would
monitor future concentrations.
No location-specific ARARs were identified for this site; therefore, there is no difference
among the alternatives with regards to these ARARs.
Action-specific ARARs would be satisfied for each of the alternatives, 50 Alternatives.
G I, 02, G3, and 04 each meet this criterion for action-specific ARARs. There are no action-specific
ARARs associated with Alternatives G I and G2, making them preferable to Alternatives 03 and G4.
Both Alternatives 03 and G4 would involve complying with the federal and state wastewater discharge
regulations. Compliance should be readily achieved, but would require more effort than Alternatives G I
and 02.
Balancing Criteria
Balancing criteria are the primary basis for comparing alternatives. These criteria relate
the alternative to the site-specific conditions. The no action alternative (G I) is not evaluated based on
the balancing criteria or the modifying criteria, since it did not meet both threshold criteria. Balancing
criteria includes long-tenn effectiveness and pennanence; reduction in toxicity, mobility, and volume
through treatment; short-term effectiveness; implementability; and cost.
Long-term Effectiveness and Permanence-This criterion has to do with long-tenn
protection of human health and the environment (reduction of risks), and adequacy and reliability of
controls. Long-tenn management ("controls") would include a S-year review, land use restrictions, and
annual groundwater monitoring. Alternatives G2, 03, and G4 each fully met this criterion, since each
alternative includes effective long-tenn management and penn anent reduction of risks through the
elimination of contamination. The monitoring requirements and ability to reduce the risk to within
established health guidelines are similar for all three alternatives.
. Reduction in Toxicity, Mobility, and Volume Through Treatment-Alternatives G3
and 04 fully meet this criterion since both include active treatment processes to remediate groundwater
contaminants. Both provide an active treatment technology that would reduce the toxicity, mobility, and
volume of contaminated media. For these two alternatives, there is linle, if any, difference in the
amounts of contaminants irreversibly destroyed or treated, and the type and quantity of residuals
remaining after treatment. Alternative G2 does not satisfy this criterion because it does not include
active treatment. Instead, it relies solely on naturally occurring processes to reduce the toxicity and
volume of the contamination; the mobility of the contamination would not be changed in this alternative.
Short-term Effectiveness-This criterion evaluates risks to workers, the community,
and the environment during the period oftime until remedial action objectives are met. Alternatives G2,
G3, and G4 each meet this criterion since each provide adequate protection and risk reduction while
groundwater contaminants are being reduced to acceptable levels. Alternative G4 is considered the most
effective in the short tenn because its remediation time of 1.4 years is substantially less than the 14 years
anticipated for Alternatives G2 and 03. Alternatives G3 and G4 involve some risks to the workers and
the community during the construction and operation of remedial equipment. However, these risks are
considered minor and very manageable. Alternative 02 does not pose these risks to workers or the
community.
Implementability-Each of the alternatives is considered fully implementable at WP14,
therefore G2, G3, and G4 each fully meet this criterion. Alternative G2 is considered the most
January 1997
2-27
OU 6 ROD, Final
-------
implementable, followed by Alternatives G4 and G3, respectively. Alternative G2 would not require the
construction or operation of remedial equipment. However, it relies upon the least reliable technology.
The calculated rate of degradation and dispersion has substantial uncertainties. Nevertheless, Alternative
G2 is the most practical alternative for WPl4ILF04 South, because of the wide-spread plume in a non-
homogeneous aquifer and the arduous and unstable topography that makes installation of an active
. treatment system difficult and costly. The LF04 bluff is eroding; therefore, although the active treatment
alternatives are implementable, it is impractical to construct such a system at WP 14ILF04 South. In
terms of the reliability of the technologies, Alternative G3 uses conventional pump-and-treat methods
which have historically had difficulties in achieving drinking water standards particularly in locations
where contamination is wide spread and resides in a non-homogeneous aquifer. Although Alternative
G4 uses an innovative technology, it is not significantly less reliable than Alternative G3, primarily
because Alternative G4 is considered to have a higher probability of being able to achieve drinking water
standards.
Cost-Alternative Gl does not have any costs associated with it. At WP14ILF04 South,
the next least expensive alternative is G2 ($462K), followed by G4 ($3, 150K) and G3 ($7, 170K). All
costs are in present value.
Modifying Criteria
Modifying criteria consider state and community concerns.
State Acceptance-The State of Alaska has been involved in the development of
alternatives for WP 14ILF04 South and concurs with the USAF and the USEP A in the selection of Alter-
native G2, long-term monitoring with institutional controls and product removal, for groundwater at
WP14ILF04 South. The Air Force will investigate and implement other remedial alternatives should the
selected remedy prove to be unsuccessful at meeting the required cleanup levels.
Community Acceptance-All of the alternatives were presented to the public in the
Proposed Plan. Based on the comments received during the public comment period, the public has no
preference of alternatives.
Soil Alternatives
Soil alternatives are developed to meet the RAOs. As discussed in Section 2.3.3 and
2.4.1, the soils at WP14 do not have any COCs or RAOs; therefore, alternatives were not developed for
the WP14 soils. The FS and Proposed Plan listed alternatives for soils, but information developed since
then has shown that soils at WP 14 do not contain constituents above cleanup levels. This eliminated the
need for further consideration of soil alternatives in this ROD.
2.4.4
Summary of Comparative Analysis of Soil Alternatives
The comparative analysis describes how each of the soil alternatives meet the CERCLA
evaluation criteria relative to each other. Alternatives were not developed for the WPI4 soils.
Consequently, a comparative analysis of soil alternatives was not conducted.
2.4.5
2.5
Selected Remedy for WP14
The selected remedy for WP14 includes Alternative G2 (long-term monitoring with
institutional controls and product removal) for the groundwater and no further action for the soils. This
remedy best meets the nine CERCLA criteria. It protects human health and the environment, and
complies with ARARs. It is effective at reducing contamination both in the short term and long term,
and is implementable, cost-effective', and acceptable to the public and the State of Alaska. This
2-28
. '" January 1997
OU 6 ROD, Final
-------
alternative reduces risks and complies with ARARs. Modeling showed that cleanup can occur within a
reasonable time (14 years of monitoring for groundwater). The known sources of contamination have
been controlled, so they are no longer a threat. This remedy will naturally degrade the residual
contamination. .
WP14:
the following:
Alternative G2 was selected because it best provides the following specific benefits at
.
Institutional controls will prevent exposure to contaminated groundwater until cleanup
levels are met.
.
Alternative G2 is the most cost-effective groundwater alternative.
.
The selected alternative does not require construction near the LF04 bluff; therefore,
slope stability will not be a problem. .
Specific components of the selected remedy are illustrated in Figure 2.5-1 and consist of
Groundwater at WP14:
.
Institutional controls on land use and water use, as specified in the Base Comprehensive
Plan, will restrict access to the contaminated groundwater throughout WP14.
Installation of wells in the contaminated plume for residential, industrial, and
agricultural use will be prohibited by the Base Comprehensive Plan until cleanup levels
have been achieved.
.
Groundwater will be monitored semi-annually and evaluated annually to determine
contaminant migration and to track the progress of contaminant degradation and
dispersion, as well as to provide an early indication of unforseen environmental or
human health risk. Five-year reviews will also assess the protectiveness of the remedial
action, including an evaluation of any changed site conditions, as long as contamination
remains above cleanup levels.
.
Recoverable quantities of free product found on top of the water table at WP 14 will be
regularly removed during groundwater monitoring events.
.
Groundwater monitoring will be discontinued if contaminant levels are below cleanup
levels during two consecutive monitoring events. In that case, no further action for
groundwater will be required.
.
During the final round of monitoring, samples will be collected and analyzed for all
constituents that exceeded MCLs during the 1994 investigation including VOCs,
SVOCs, and metals. These results will be evaluated before a final determination is made
that groundwater meets all cleanup requirements.
.
All groundwater is expected to be cleaned up within 14 years.
January 1997
2-29
OU 6 ROD, Final
-------
~I
'-'
S'
"Tt
5.
!!.
Groundwater
Soil
t.J
I
\,J
o
.....
~
c:
~
Long-Term Monitoring with Institutional Controls
and Product Removal.
Annual Removal of Beach Debris.
-
\D
\0
-I
Figure 2.5-1. Selected Al8atives (or WPI4 and LF04
-------
Soil at WP14:
.
No further action will be required for the soil at WP14.
The estimated time for groundwater cleanup is 14 years. Groundwater will be monitored
to evaluate the progress of degradation and dispersion. Further response actions, coordinated with the
regulatory agencies, may be considered if monitoring finds unacceptable contaminant migration or
unacceptable reduction in contaminant concentrations.
Because the remedy will result in contaminants remaining on-site above health based
levels, a review will be conducted within 5 years after commencement of remedial action. The review
will ensure that the remedy continues to provide adequate protection of human health and the
environment. The cleanup levels to be achieved (i.e., remediation goals) through the selected remedy for
COCs at WPl4 are presented in Table 2.5-1.
The selected remedy in~ludes provisions for the preparation of a workplan for continued
environmental monitoring of the affected media. The workplan will include specific details regarding
the number and location of monitoring points, as well as guidelines for eliminating select monitoring
points as cleanup occurs. Environmental monitoring will be discontinued at WP14 when the remediation
goals have been satisfactorily achieved (Table 2.5-1). This determination will be made jointly by the
USAF, the USEPA, and the State of Alaska pursuant to the Federal Facility Agreement.
2.5.1
Statutory Determinations
The selected remedy satisfies the requirements under Section 121 of CERCLA to:
.
Protect human health and the environment;
.
Comply with ARARs;
.
Be cost effective; and
.
Utilize permanent solutions and alternative treatment technologies to the maximum
extent practicable.
Protective of Human Healtb and tbe Environment
The selected remedy is protective of human health and the environment. There are no
current points of exposure; therefore, risks are low. Institutional controls will protect against potential
risk by assuring that the contaminated groundwater will not come in contact with people until RAOs
have been met.
Risks were calculated using assumptions regarding exposure pathways and the time
receptors were exposed to the contaminants. Each exposure was estimated conservatively in a manner
which tends to overestimate the actual risk. Risk management decisions were made considering the
uncertainty in the assumptions used in the risk assessment. At WP14, the shallow groundwater is not
used and is not expected to be used in the future, so existing risks and potential risks are significantly
less than the worst-case risk.
There are no direct current receptors of groundwater at WP14. Institutional controls will
protect against the potential risk to human health by ensuring that contaminated shallow aquifer
January 1997
2-31
OU 6 ROD, Final
-------
Table 2.5-1
Identification of Cbemical-Specific ARARs and Remediation Goals, WP14/LF04 Soutb
Elmendorf AFB, AK
Muimum Basis for
LocatioD Chemical CODcentration Remdiation Goal Remediation Goal'
Groundwater:
WPI4 Benzene 1390 J1g/L 5J1g/L MCL
Ethylbenzene 1410 J1g/L 700 J1g/L MCL
Toluene 319{) J1g/L I 000 J1g/L MCL
LF04 South Benzene 3400 11g/L 5 J1g/L MCL
Ethylbenzcne 722 11g/L 70011g/L MCL
Toluene 3020 J1g/L .1000 J1g/L MCL
1,2~Dichloroethane 32.6 J1g/L SJ1g/L MCL
Methylene chloride 6.53 11g/L SI1g!L MCL
I Maximum Contaminant Level (MCL); 40 CFR ~ 141.6\ for Federal MCLs, and \8 MC 80.070 for State MCLs. Federal and State MCLs
are identical for the COCs.
2-32
January 1997
OU 6 ROD, Final
-------
grou'ndwater will not be consumed by people until cleanup levels (MCLs) are met. The time required to
achieve MCLs is not known, but could be as short as 14 years based upon groundwater modeling results.
Modeling of contaminant flow at Elmendorf AFB showed that conditions are not expected to deteriorate
at WP14. Modeling predicts that, over time, cleanup objectives will be met by degradation.
Applicable or Relevant and Appropriate Requirements (ARARs)
Cbemical-Specific ARARs - Chemical-specific cleanup levels (i.e., remediation goals)
for OU 6 are identified in Table 2.5-1. The Maximum Contaminant Levels (MCLs) established for
drinking water under State and Federal laws are relevant and appropriate to groundwater contaminants of
concern at WPI4 as a chemical-specific regulation. Semi-annual groundwater monitoring will document
compliance with MCLs.
Location-Specific ARARs - There are no specific ARARs which must be met because
of the location of the contamination and remedial actions at WP14.
Action-Specific ARARs -There are no action-specific ARARs for the selected remedy
at WP14.
Cost Effectiveness
The selected remedy is the most cost effective of the alternatives because it affords
overall effectiveness proportional to its costs.
Utilization of Permanent Solutions and Alternative Treatment Tecbnologies to tbe
Maximum Extent Practicable
The USAF and the USEP A have determined that the selected remedy represents the
maximum extent to which permanent solutions and treatment technologies can be used in a cost-effective
manner at WP14. 'Ofthose alternatives that are protective of human health and the environment and
comply with ARARs, the USAF and the USEPA have determined that the selected remedy provides the
best balance of tradeoffs in terms of long-term effectiveness and permanence; reduction in toxicity,
mobility, or volume achieved through treatment; short-term effectiveness; implementability; cost (as
discussed in the preceding section); the statutory preference for treatment as a principal element~ and
considering State and community acceptance. The selected remedy will permanently remove the
contaminants through natural, biological break down of the contaminants into harmless chemical
compounds. The State of Alaska concurs with these determinations.
Preference for Treatment as a Principal Element
Because of the substantial cost of actively treating groundwater, the potential for natural
degradation in 14 years, and the fact that there are no current receptors of groundwater, long-term
monitoring with institutional controls and product recovery is a more favorable means of addressing
groundwater contamination than active treatment.
Documentation of Significant Cbanges
The Proposed Plan listed soil and groundwater constituents with concentrations in excess
of cleanup goals (ACM guidelines and MCLs). COCs were then identified in Section 2.3.3 by evaluating
whether a constituent exceeded regulatory levels and/or contributed to risk. Mitigating circumstances
were also evaluated when establishing COCs including sampling techniques and whether the
contamination was in the smear zone. Thus, the list of contaminants exceeding cleanup levels in the,
Proposed Plan was not the same as the list of COCs defined in the ROD.
2.5.2
January 1997
2-33
OU 6 ROD, Final
-------
The selected remedy for groundwater at WP 14 was the preferred alternative presented in
the Proposed Plan (Table 7 of the Proposed Plan). No significant changes were made to this alternative.
One significant change from the Proposed Plan was the use of ACM Level C as opposed
to Level B for soils at WP14. This change occurred while re-examining the ACM scoring criteria during
the preparation of the ROD. Consensus was reached between ADEC, USEPA, and USAF that the ACM
Level C guidelines is more appropriate for the site conditions at WP14. As a result, no COCs were
established for shallow soils at WP14 and no further action is necessary. Thus, the preferred alternative
in the Proposed Plan (Excavation, Thermal Treatment, and Backfilling) is not the same as the selected
remedy (No Further Action).
The selected remedy for deep soils also changed. A treatability study at WP 14 indicated
that deep soil contamination was actually smear zone contamination; therefore, as discussed in Section
2.3.3, no COCs were established for deep soils. The preferred alternative in the Proposed Plan was
Bioventing. This was changed to No Further Action for the selected remedy. All changes are a logical
outgrowth of the Proposed Plan.
OU 6 ROD, Final
2-34
January 1997
-------
SECTION THREE
-------
3.0
TABLE OF CONTENTS
Page
SOURCE LF04 . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-]
3.]
3.2
3.3
3.4
3.5
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.1.1 Land Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-]
3.1.2 Hydrogeology and Groundwater Use. . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . 3-]
Site History and Enforcement Activities. . . . . . . '. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.2.] Identification of Activities Leading to the Current Contamin~tion
at LF04 [[[ 3-3
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . , 3-4
3.3.] Nature and Extent of Contamination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3.3.2 Risk Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-] 9
3.3.3 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-22
Remedial Action Objectives, Alternatives, and Comparative Analysis for LF04 ... 3-25
3.4.1 Remedial Action Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-25
3.4.2 Groundwater A]ternatives . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . 3-26
3.4.3 Summary of Comparative Analysis Of Groundwater Alternative's. . . . . . . . . 3-26
3.4.4 Soil Alternatives. . . " . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . 3-26
3.4.5 Summary of Comparative Analysis of Soil Alternatives. , . . . , . . . , . . . . . . 3-27
Selected Remedy for LF04 """""""""""""""""""""'" 3-28
3.5.] Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . 3-30
3.5.2 Documentation of Significant Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-31
LIST OF FIGURES
Page
3. ]-1
Location Map for Source Area LF04 ...........................................". 3-2
3.3-] 'Chlorinated Solvent Plume in the Groundwater at LF04 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-24
LIST OF TABLES
Page
3.3-1
Summary of Groundwater Analytical Results for the Bluff Area, at Source LF04
Elmendorf AFB, AK . .. .. . . . . . . . . ... .... ... . ... . .. .. . . . . . .. . .. .. .. . . . . . . . . . . . 3-5
3.3-2
Summary of Groundwater Analytical Results for the Beach Area, at Source LF04
-------
3.3-3
3.3-4
3.3-5
3.3-6
3.3-7
3.5-1
LIST OF~T ABLES (CONTINUED)
Page
Summary of Seep Analytical Results at Source LF04,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Summary of Surface Soil Analytical Results at Source LF04,
Elmendorf AFB, AK ..... ......................... ... .............. ...... . . . . . 3-13
Summary of Subsurface Soil Analytical Results at Source LF04,
Elmendorf AFB, AK . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 3-16
Summary of Human Health Risks at LF04, Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . 3-21
Summary of Contaminants of Concern at LF04, Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . 3-23
Identification of Action-Specific ARARs, LF04, Elmendorf AFB, AK ................. 3-31
11
-------
Section 3.0
SOURCE LF04
The following subsections describe the physical description, land use, groundwater use,
and hydrogeology of LF04. The identification of activities which led to the current contamination at
LF04 is also included. The discussion of the regulatory and enforcement history ofLF04, the role of the
response action at LF04, and community participation in the response action are included in the general
au 6 discussion in Section 1.0. The detailed discussion of the hydrogeology at LF04 was combined
with the description of the hydrogeology at WP14, and is presented in Section 2.1.2. These discussions
were combined because of the close proximity between Sources LF04 and WP14 on the Elmendorf
Moraine.
Site Description
Source LF04 is a landfill located east of Knik Ann Bluff on the west side of Elmendorf
AFB (Figure 1.1-2). As indicated by its name, the Knik Bluff Landfill (LF04) coincides mostly with the
presence of a steep bluff which drops from an elevation in excess of 200 feet down to sea level. The
landfill parallels Knik Ann for a distance of approximately 3000 feet and is approximately 600 feet wide
(Figure 3.1-1). Along the southern end of the landfill, the ground surface slopes toward Knik Ann and
the bluff is less pronounced. .
3.1
LF04 was used as a surface dump from 1945 to 1957. Debris appears to have been
dumped directly off of the bluff, or used as a means of filling ravines in the side of the bluff. Old cars,
construction rubble, and small quantities of general refuse have been dumped at the landfill, in addition
to an unknown number of 55-gallon drums. Debris from the landfill has drifted downslope onto the
beach over time. Observations made from this beach suggest that the landfill material was also burned in
place. Tidal action appears to be eroding the bluff material and increasingly exposing portions of the
landfill. Several groundwater seeps occur on the Knik Ann Bluff or at the beach.
Active and abandoned POL lines cross the southern extent of LF04. A pumphouse
serving the lines (Building 30-790) is also located at the south end of the site.
Land Use
LF04 is currently designated as a "restricted use area" in the Base Comprehensive Plan.
This designation provides for recreational use of the parcel (cross country skiing, etc.) and for
construction of unmanned facilities such as a parking lot, storage building, or taxiway, but prohibits the
construction of any sort of manned facility such as an office building or a residence; Drilling into the
shallow aquifer is also restricted by the Base Comprehensive Plan. As a fonner landfill, LF04 will
maintain this designation indefinitely.
3.1.1
There are no known historic buildings, archeological sites, wetlands, floodplains, or rare
or endangered species at LF04.
3.1.2
Hydrogeology and Groundwater Use
The discussion of the hydrogeologic setting for sources LF04 and WP 14 have been
combined because of their close proximity on the Elmendorf Moraine. That discussion is found in
Section 2.1.2 of this document. For a more general description of Elmendorf AFB geology and
hydrogeology, the reader is referred to Section 1.1, or to the au 6 Remedial InvestigationlFeasibility
Report (USAF. 1996b).
January 1997
3-1
au 6 ROD; Final
-------
n':r'('
,~
I
f
"t
.*
~
~
" 'i,.': .. ' " ;:.: .' '-...-- >'" j'
; :. ,1 -,,...; " /',' " "
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'-.':,:' ,." J,- '~I ' I
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. '1\\\ ,----' \,;, c .~o JOO
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\ \ I I I . I III / { J'
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I! I ) {I \ ~ 'i, I :::: ( - 250 -
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,'j /: " : ~~~~~ r---- -- =~) .~ '-
Ins:ollolion -'" ,:,' .' ~ ", ') "; 'J \",,- ~,--, I ' - - -
Boundary ~/~ 1, I' ,,'( i r;/' I ... = = = ... =-=~-:----ru
I"~I" \ ': J'," ' : -:"', '{,- ~, ,,-,;;-;:-~-~-~~':e -,'
i ' 't", I, ~' POL Line
/-} \ "j & i Ii I ~~~::;i" ,0 J'~(----"
/: II' \,~.:' ,,;:';' ~
/' / .1 I\., "~" -:(:",' '.'; Abano.one~
, II I I .. ,~" ~'", ;' POL Line,
........ " ' , )f,' '," ('- ~ -
I' 1'1 I "~-' ".,,~;. ~....-
"\ /! j, I "I ,,/. " \,.--' t;;?:"-:';:'-
. , ,~, , ,.."" -'''; ... ... L-.
1'(.' I ~ i II ';,{./~ --::.,...--:-:::.... \
I I ' . ' ~':.' -:>- -:-.-. ... .
;' i II( !~!,; I'!', ,lll~~~:4 S~UT-':
. "\ " ," f "
,\rU ,:;,: "rl -\1:'
,.-/ /.i~/l:/(,'~.".~ l~::,
: . I; . I'" \\
,(,- I ,/ l i : I:;,' \' \
, ' I ! I I )I, \ ,\
. ,/ (,.' . "" ."
/ L.. :.--J./.;JL.JJI ".
ELMENDORF' AF'B
LEGEND
Abando'1ed POL Line
.----- Lt04
_u- Lt04
South Eoundary
NorthjEeccr Boul"dary
ce
-
?
~,
2
fH'
c..
r......
/ "-
( \./""",
\.
"""\
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./
-----""'~ --
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,
\ /---."''.
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":',~::;;::- :
-'- "---............
"'-,
'\
Figure 3.1-1. Location Map for Source Area LF04
au 6 ROD, Final
'<
3-2
January 1997
-------
In general, three aquifers were detected during the course of the RI at LF04 and WP14.
All three aquifers are believed to vertically communicate. The aquifers are primarily silty sands
occurring as perched lenses within the morainal deposits on the bluff. The lowermost aquifer is near the
level of the beach. Substantial fine-grained, clayey materials near this interval are believed to coincide
with the top of the Bootlegger Cove Clay.
Groundwater flow is generally to the west, towards the Knik Arm. A generalized
hydrogeologic conceptual model for this area is presented in Section 2.1 as Figure 2.1-2. The estimated
hydraulic conductivity for this area ranges from 1.12E-3 to 3.59E-5 cm/sec in the various perched
aquifers.
The groundwater in the regional shallow aquifer on base, which is believed to
correspond roughly with the third aquifer at the beach at LF04, is not used for any purpose. Its future
use, even if the aquifer was uncontaminated, is generally limited because of the higher yield of the
deeper confined aquifer which underlies the Bootlegger Cove Clay. In the vicinity of LF04, the fine-
grained nature of the perched aquifer material, and the laterally discontinuous nature of the perched
aquifer lenses, would make these perched aquifers unsuitable as drinking water supply aquifers. In
addition, the instability of the bluff slope at LF04 makes it highly unlikely that the area could ever be
used residentially.
3.2
Site History and Enforcement Activities
The following section identifies the activities which lead to the current contamination at
LF04. The regulatory and enforcement history for LF04 is included in the general discussion presented
for au 6 in Section 1.0, as are the discussions of the role of the response action and the community
participation in the response.
3.2.1
Identification of Activities Leading to tbe Current Contamination at LF04
Soil contaminants detected'at LF04 include pesticides, dioxins and furans, metals, PCBs,
and fuel-related constituents. Similar contaminants were identified in the groundwater, as well as
halogenated volatile organic compou'nds (HVOCs).
There are several principal sources of contamination at Source LF04, including waste
management practices, leaking POL facilities, and migration from upgradient sources. Due to the
landfilling activities conducted at LF04, it is likely that contaminants from each of the groups mentioned
above were made available to contaminate the soil and groundwater. The elevated concentrations of
inorganic constituents detected during this investigation most likely indicate that materials containing
heavy metals (such as automotive and aviation batteries) have been dumped over the edge of the bluff.
Drums previously observed on the ground surface on the bluff also constitute a potential contaminant
source at LF04, and may be responsible for the low levels of solvents or fuels detected in soil and
groundwater samples in the area. Old transformers act as a source of polychlorinated biphenyls (PCBs);
various metallic wastes act as the metals source, etc. Pesticides were also prevalent at LF04. Based on
the extreme heterogeneity of occurrences of pesticides, and heavy occurrences primarily adjacent to
access roads, the pesticide contamination is believed to be the result of incidental disposal of residual
pesticides in the course of pesticide application events.
, At the southern end of LF04, a pumphouse and various fuel lines and valve pits act as a
second principal contaminant source for fuel-related constituents. Probable evidence of leakage from the
POL facilities at LF04 was observed during the RI.
January 1997
3-3
OU 6 ROD, Final
-------
Groundwater migration from WPI4 and/or other upgradient sources comprise another
source of contamination for LF04. As described in Section 3.1.2, groundwater is present in several
aquifers within the LF04/WP14 area, and substantial vertical and lateral mixing between these aquifers
allows the downgradient spread of dissolved phase contaminants across this site. Downward percolation
of groundwater through contaminated soils at LF04 can also act as a contaminant source for the shallow
aquifer. Seasonal fluctuations in the water table have resulted in a smear zone being detected at the base
of the vadose zone within LF04. A schematic of the potential migration and exposure pathways for fuels
and solvents through the soil and into the groundwater is presented in Section 2.2.1, Figure 2.1-1, for
Sources WPl4 and LF04.
Prior to the RI conducted at LF04 in 1994, LF04 had been addressed under the following
studies:
.
IRP Phase I!II Records Search and Statement cif Work (Engineering-Science, 1983);
.
IRP Phase II Remedial Investigation (JMM/Harza Environmental, 1988);
.
IRP Phase II Stage 3 Work Plan (Harding Lawson, 1988); and
.
RCRA Facility Assessment Report (ADEC, 1988).
Landfilling practices at the LF04 Knik Bluff Landfill ceased in 1957. The pumphouse
serving the active and abandoned lines (Building 30-790) has been taken out of service. The active POL
line at LF04 has been tested and determined to be sound. The abandoned line was reportedly drained of
fuel and abandoned in sections in place. Buried tanks which serviced the pumphouse were removed in
1996.
Site Contamination. Risks. and Areas Requirine Response Actions
This section identifies the areas which were investigated, and those that require remedial'
action. These areas were chosen based on the risk that contaminants pose to human health and the envi-
. ronment. The basis of this analysis is the data collected during the Remedial Investigation (RI) which
identified the nature and extent of contamination at LF04.
3.3
Nature and Extent of Contamination
During the RI, samples of soil and groundwater were collected and analyzed for organic
and inorganic constituents. Potentially significant levels of organic contaminants were detected in both
the soil and groundwater at LF04. These contaminants include fuels and fuel constituents, solvents,
metals, pesticides, semi-volatile organic compounds, and dioxins. The contamination present at LF04 is
. associated with contaminant transport in the vadose zone, dissolved aqueous transport, and volatilization,
as well as surface water flow at the seeps. These transport mechanisms are pictorially represented for
LF04 in Figure 2.2-1.
3.3.1
Tables 3.3-1 through 3.3-5 list the frequency of occurrence and maximum concentrations
of all constituents which were detected during the RI in groundwater and soil. The tables do not include
results below the detection limit. The MCLs for groundwater and the ACM guidelines for soil are also
listed on the tables for all constituents. Results are separated between "indicator parameters" and
"contam inant parameters."
OU 6 ROD, Final
3-4
January 1997
-------
Table 3.3-1
Summary of Groundwater Analytical Results for Bluff Area at Source LF04
Elmendorf AFB, AK
Frequency of Location of
Method Analyte MCL' Mllimum Detections Mnimum
(units) Result Total Hits!
Total Samples Result
Indicator Parameters
5W6010. Total (mgIL) Aluminum -- 100 14114 "'-302
Calcium - 182 14/14 K-302
Iron -- 146 14114 K-302
Magnesium - 67.7 14/14 K-302
Potassium .. 8.54 13/14 K-302
Sodium -- 15 14/14 K-302
SW6010, Dissolved Aluminum .. 0.275 411 MW-61
(mg/L) Calcium .. 99.2 711 MW-61
Iron .. 15.6 711 MW-74
Magnesium -- 34.7 711 MW-61
Potassium - 2.75 711 MW-61
Sodium .. 13.2 711 MW-67
Contaminant Parameters
SW8260 (j.lgIL) Acetone .. 27.1 b 10/14 MW-67
Benzene 5 3400 14/14 MW-61
2-Butanone(MEK) .. 32.4 b 7/14 MW-61
Chloroethane - 0.83 3/14 MW-61
Chloroform 100 1.25 2114 MW-67
Chloromethane -. 3.72 10/14 K-302
1.2-Dichlorobenzene 600 0.6 1/14 MW-17
1.1-0ichloroethane -. 2.05 1114 MW-17
1.2-Dichloroethane 5 38.7 b 7/14 MW-61
cis-I.2-0ichloroethene 70 20 3/14 MW-17
1.2-0ichloropropane 5 0.31 1/14 MW-61
Ethylbenzene 700 722 13/14 MW-77
Methylene chloride 5 290 b 101\4 MW-67
4-Methyl-2-pentanone(MI BK) .. 8.95 4/14 MW-61
Tolucne 1000 3020 14/14 MW-77
1.1.1- Trichlorethane 200 0.19B 1114 MW-77
Trichloroethene 5 0.47 2114 MW-77
Vinyl chloride 2 0.8 11\4 MW-61
m&p-Xylene -- 1640 13/14 MW-77
o-Xylene .. 498 12114 MW-77
SW8080 (j.lgIL) Aldrin -- 0.0171 5/14 K-302
alpha-BHC .. 0.0197 6114 MW-77
beta-BHC .. 0.0688 1114 MW-78
gamma-BHC(Lindane) 0.2 0.0447 11/14 MW-77
4,4'-000 -- 0.023 1114 MW-61
4.4'-DDE n 00179 1114 MW-61
January 1997
3-5
OU 6 ROD, Final
-------
Table 3.3-1
(Continued)
Frequency or Location of
Method Maximum Detections
(uoits) Anllyte MCL' Result Tobl Hits! Maximum.
Total Samples Result
SW8080 (1Ig!L) 4,4'-DDT - 0.028 2/14 MW-61
(continued) Dieldrin - 0.0128 6/14 MW-61
Endosulfan 1 - 0.0087 2/14 K-J02
Endrin Aldehyde - 0.OJ27 1/14 MW-61
Heptachlor - 0.0177 5/14 K-J02
Heptachlor epoxide - 0.0121 PB 10/14 K-J02
SW8270 (1Ig!L) Benzoic acid - 26.J 2/14 MW.77
2.4-Dimethylphenol - 1.89 2/14 MW-6J
Diethylphthalate 6 0.516 1/14 K-J02
Dimethylphthalate - 41.3 4114 MW-77
bis(2 - E thylhexyl)phthalate 6 24.2 1114 MW-61
2-Methylnaphthalene - 6J.1 8114 MW-77
2-Methylphenol (o-cresol) - 5.64 2/14 MW-77
4-Methylphenol/ -- 31.7 F 4/14 MW-77
3-Methylphenol
Phenol - 88.3 5114 MW-61
SW8J10 (1Ig!L) Acenaphthene - 20.J 8114 MW-67
Acenaphthylene - 2.25 2/14 MW -77
Anthracene - 0.34 1114 K-302
Benzo(b)tluoranthene 0.2 0.0225 B 1114 K-J02
Chrysene 0.2 0.14 1114 K-302
Fluorene - 1.49 8/14 MW-67
Naphthalene - 122B 10114 MW-77
Phenanthrene - 0.454 1114 MW-77
SW6010. Total (mg!L) Barium 2 0.699 4114 K-302
Beryllium 0.004 0.0019J B 8114 K-302
Cadmium 0.005 0.00628 1114 MW-61
Chromium 0.1 0.149 5/14 K-302
Cobalt - 0.0688 7114 K-302
Copper 1.31 0.345 4114 K-J02
Manganese - 20.8 14114 MW-77
Nickel 0.1 0.243 5/14 K-302
Selenium 0.05 0.0911 1114 K-J02
Vanadium - 0.287 3114 K-J02
Zinc - 0.401 14114 K-302
SW7060, Total (mg!L) Arsenic 0.05 0.0748 14/14 K-302
SW7421. Total (mgIL) Lead 0.0151 0.0447 6114 K-302
SW6010. Dissolved Barium 2 0.0669 7n MW-61
(mg!L) Beryllium 0.004 0.00129 B 117 MW-61
Cadmium 0.005 0.00771 1/7 MW-61
Chromium 0.1 0.00538 117 MW-67
Cobalt -. 0.00738 1/7 MW-67
OU 6 ROD, Final
3-6
January 1997
-------
Table 3.3-1
(Continued)
Frequency of Location of
Method Analyte MCL' Mnimam DrtrrtioDS M8Ilmum
(UDitS) Rrsult Total Hits!
Total Samples Result
SW6010, Dissolved Manganese - 6.92 7n MW-67
(mgll.) (continued) Zinc -- 0.017 B 5/7 MW-67 .
SW7060, Dissolved Arsenic 0.05 0.029 7n MW-67
(mgll.)
B
F
p
I Maximum conlaminant level (MCL); 40 CFR ~ 141.61 for Federal MCLs, and 18 AAC 80.070 for Slate MCLs. Federal and Slate
MCLs are identical for the listed constituents. .
2 From 40 CFR, Section 141.11 for inorganics and Section 141.12 for organics (effective I July 1991); however, the lead level is effective
only until 7 December 1992. There is no longer an MCL for lead or copper (56 Federal Rel!ister 26460, June 7, 1991); however, there is
an action level of 0.0 I 5 mg/l for lead and 1.3 mgll. for copper.
b - Due to high concentrations of other target compounds in the sample, or to interference by non-target analytes, the sample could not
be run at a dilution factor of one. The flagged analyte concentrations is less than the blank UTL times the sample dilution factor.
. Sample concentration was less than or equal to the blank UTL.
. Co-elution or interference was suspected.
- Analyte quantitation not confirmed. Results from primary and secondary GC columns differ by greater than a factor of three.
January 1997
3-7
au 6 ROD, Final
-------
Table 3.3-2
Summary of Groundwater Analytical Results for Beach Area at Source LF04
Elmendorf AFB, AI(
Method Frequency or Locadon or
Analyte MCL' Maximum Ddections Masimum.
(units) Result Total Hits!
Total Samples Result
Indicator Pnameten
SW80lSME (ligIL) Unidentified organics [UDR.O] - 840 11/\3 K-304
SW801 SMP (ligIL) Unidentified organics [UGRO] - 8700 121\3 K-304
Xylene (total) 10000 292 121131 MW-81
SW6010, Total (mgIL) Aluminum -- 23.3 12113 MW-8S
Calcium ..: 196 13/13 MW-8S
Iron - 39.S 13/13 MW-8S
Magnesium - 121 13/13 MW-84
Potassium - 16.2 13/13 MW-83
Sodium -- 480 13/13 MW-83
SW6010. Dissolved Aluminum - 0.IS3 B 21S MW -84
(mgIL) Calcium - 179 4/S MW-8S
Iron .- 6.8 4/S MW-8S
Magnesium .. 120 4/S MW-84
Potassium - IS.6 4/S MW.83
Sodium .- 4S8 S/S MW-83
Contaminant Paramders
SW80lSME (J.lgIL) Jet Fuel (JP-4) - 903 2113 K-304
SW80lSMP (J.lgIL) Gasoline -- SI60 1/13 K-304
SW8260 (JAgIL) Acetone -- 9.9S B 13/13 MW-84
Benzene 5 5.8 9/13 K-304
2-Butanone(MEK) .. 2.18 B 4/13 MW.8S
Chlorocthane .. 0.12 B 1/13 MW-82
Chloroform 100 0.2 2/13 MW-82
Chloromethane -. S.23 9/131 MW.81
1.2-Dichlorocthane S 0.9 B 2/13 MW-84
cis.I,2-Dichlorocthene 70 8.28 S/13 MW -82
trans-I,2-Dichlorocthene 100 S.17 4/13 MW -82
Ethylbcnzene 700 SO.2 9/13 MW-81
Methylene chloride S S.71 10/\31 MW-84
1,1.2,2.Tetrachloroethane - 0.S3 2/13 MW-82
Toluene 1000 28.7 13/13 K-304
Trichlorocthene .- 2.57 4/13 MW-82
Vinyl chloride 2 0.14 21\3 MW.82
m&p-Xylene -- 202 9/13 MW.81
o-Xylene - 32.9 10/13 MW-81
SW8080 (JAgIL) Aldrin .. 0.0243 4/13 MW-8S
alpha-BHC - 0.0119 P 2/13 MW-8S
gamma-BHC(Lindane) 0.2 0.0246 S/13 MW -83
4.4'-DDD -- 0.0908 5/\3 MW.8S
4,4'-DDE -- 0.0875 3/13 MW-8S
4,4'-DDT -- 0.0382 3/13 MW-8S
OU 6 ROD, Final
3-8
January 1997
-------
Table 3.3-2
(Continued)
Frequency or Loc:alion or
Method Analyte MCL' Maximum Detections Maximum
(units) Result Total Hltsl
Total Samples Result
SW8080 (llg/l) Dieldrin - 0.0324 2/13 MW -83
(continued) Endosulfan II .. 0.0053 P 1/13 MW-85
Endrin Aldehyde -- 0.032 1113 MW-85
Heptachlor -- 0.0105 P 1113 MW-85
Heptachlor epoxide - 0.0603 P 4113 MW -85
SW8270 (1i~1L) DimethylphthaJate -- 12.7 5/13 MW -80
bis(2 - Ethylhexyl)phthal ate 6 3.08 B 3/13 MW-85
2-Methylnaphthalene - 12.1 3113 K-304
4-Methylphenoll -- 2.07 F 2/13 MW -83
3-Methylphenol
SW831 0 (lig!L) Acenaphthene - 4.04 2/13 MW-85
Acenaphthylene -- 2.4 2113 MW-85
Anthracene -- 0.307 B 2/13 MW-85
Fluoranthene -- 0.241 1/13 MW-85
Fluorene -- 1.2 6/13 MW-85
Naphthalene -- 8.83 . 13113 MW-83
Pyrene - 0.162 1/13 MW-85
SW6010, TCoIaJ (mg/l) Antimony 0.006 0.0856 1/13 MW-85
Barium 2 0.395 13113 MW-85
Beryllium 0.004 0.00167 B 10113 MW-82
Cadmium 0.005 0.00976 4/13 MW -84
Chromium 0.1 0.04 3/13 MW-85
Cobalt -- 0.0163 5/13 MW-85
Copper 1.3' 0.108 2/13 MW-85
Manganese - 4.03 13/13 MW-81
Molybdenum -- 0.0102 2/13 MW-80
Nickel 0.1 0.0624 4/13 MW-85
Vanadium -- 0.0554 3/13 MW-85
Zinc -- 0.216 10/13 MW-85
SW7060, Total (mg/L) Arsenic 0.05 0.0252 7113 MW-84
SW7421, Total (mg/l) Lead 0.015' 0.0508 4/13 MW-85
SW6010. Dissolved Barium 2 0.25 4/5 MW-85
(mg/l) Beryllium 0.004 0.0017 B 3/5 MW-83
Cadmium 0.005 0.00491 1/5 MW-84
Chromium 0.1 0.00861 1/5 MW-85
Cobalt - 0.00853 1/5 MW-85
Manganese -- 3.96 5/5 MW-81
Zinc - 0.0218 3/5 MW-81
January 1997
3-9
au 6 ROD, Final
-------
Table 3.3-2
(Continued)
Frequency of Locadon of
Method An.lyte MCV Muimum Detections Maiimum
(units) Result Total Hits!
Total Samples Result
SW1060, Dissolved Arsenic 0.05 0.0113 2/5 MW-84
(mgll)
I Maximum contaminant level (MCL); 40 CFR ~ 141.61 for Federal MCLs, and 18 MC 80.010 for Stale MCLs. Federal and State
MCLs are identical for the listed constituellfS.
1 Frequency "hitS' calculation does not include one or more resultS removed from the data set because they did not meet QAlQC criteria.
Total sample count includes all samples analyzed for the indicalCd parameler.
I From 40 CFR. Section 141.11 for inorganics and Section 141.12 for organics (effective I July 1991); however. the lead level is effective
only until 1 December 1992. There is no longer an MCL for lead or copper (56 Federal ReRister 26460. June 1, 1991); however~ there is
an action level of 0.01 5 mgll for lead and 1.3 mgll for copper.
B - Sample concentration was less than or equal to the blank UTL.
F - Co-elution or interference was suspected.
P - Analyte quantitation not confirmed. Results from primary and secondary GC columns differ by greater than a factor of three.
OU 6 ROD. Final
3-10
January 1997
-------
Table 3.3-3
Summary of Seep Analytical Results at Source LF04
Elmendorf AFB, AK
Frequency or Lourion of
Method Mllimum Detections
(units) Analyte MCL I Result Total Hits! Maximum
Total Samples Result
Indicanor Parameters
SW8015ME (j!g/L) Unidentified organics [UDRO} - 3860 1/11 SP-02
SW8015MP (j!g/L) Unidentified organics [UGRO} -- 9480 b 3/11 SP-02
Xylene (total) 10000 1680 9/11 SP.02
SW6010, Total (mg/L) Aluminum - 1.94 9/11 SP-02
Calcium .. 132 11/11 SP-06
Iron -- 61.1 11111 SP.Q2
Magnesium -- 38.6 11111 SP-06
Potassium - 2.25 II1I1 SP-06
Sodium - 23.8 11111 SP-06 .
Contllrminant Parameters
SW80 15MP (j!g/L) Gasoline - 9150 3/11 SP-02
SW8260 (j!g/L) Acetone - 15.5 FB 9/11 SP-03
Benzene 5 289 6/11 SP.:o2
Carbon disulfide -- 0.58 2/11 SP.Q2
Chloromethane -- 2.23 B 3/11 SP-OJ
I.I-Dichloroethane - 0.1 B I1I1 SP.03
1.2-Dichloroethane 5 1.41 B 3/112 SP-OI
Ethylbenzene 700 290 X 6/11 SP.02
Methylene chloride 5 6.53 9/11' SP-06
Styrene 100 9.85 1/1 I SP-02
Toluene 1000 840 5/11 SP-02
m&p-Xylene -- 896 X 6/11 SP-02
o-Xylene -- 485 5111 SP-02
SW8270 (j!g/L) 2 -4- Dimethylphenol -- 18.2 2/11 SP-02
2-Melhylnaphthah;ne - 18.2 4/11 SP-04
2-Methylphenol (o-cresol) -- 16.9 2/11 SP-02
4-Methylphenoll -- 17.3 F 2/11 SP-02
3-Methylphenol
Phenol -- 4.36 1/11 SP-02
SW8310 (j!g/L) Acenaphthene -- 27.1 4/11 SP-02
Acenaphthylene -- 7.23 1/11 SP-04
Benzo(b)t1uoranthene 0.2 0.0819 3111 SP-02
Be nzo(k)f! uoranthene 0.2 0.0075 B 2/1 I SP-03
Chrysene 0.2 0.136 2/11 SP-02
Fluorene - 1.26 3111 SP-04
N aphtha/ene -- 51.5 3/11 SP.04
SW6010. Total (mg/L) Barium 2 0.0698 11111 SP.03
Beryllium 0.004 0.0016R B 2/11 SP-07
Chromium 0.005 0.00911 1/11 SP.Q2
January K 997
3-11
au 6 ROD, Final
.<
-------
Table 3.3-3
(Continued)
FrequeoC)' or Location or
Mdhod I ADalyte MCL1 Maximum Detections Maximum
(units) Result Tobl Hits!
Tobl Simples Result
SW6010, Total (mgIL) Cobalt - 0.00844 4/11 SP-04
(continued) Copper 1.3' 0.0118 I111 SP-02
Manganese -- 7.94 \111 SP-02
Molybdenum -- 0.00967 2111 SP-02
Nickel 0.1 0.0182 1/11 SP-02
Vanadium - 0.0202 2111 SP-02
Zinc - 0.0169 B 7/11 SP-02
SW7060, Total (mgIL) Arsenic 0.05 0.0963 7/11 SP-02
SW7421, Total (mgIL) Lead 0.015' 0.00303 1/11 SP-02
I Maximum conlaminant level (MCL); 40 CFR ~ 141.61 for Federal MCLs, and 18 AAC 80.070 for Slate MCLs. Federal and Slate
MCLs are identical for the listed constitUents.
: Frequency "hits. calculation does not include one or more results removed from the dala set because they did not meet QAlQC criteria.
TOlal sample count includes all samples analyzed for the indicated parameter.
, From 40 CFR. Section 141.11 for inorganics and Section 141.12 for organics (effective I July 1991); however, the lead level is effective
only until 7 December 1992. There is no longer an MCL for lead or copper (56 Federal Ree.ister 26460, June 7,1991); however, there is
an action level of 0.0 15 mgIL for lead and 1.3 mgIL for copper.
b - Due to high concentrations of other target compounds in the sample, or to interference by non-target analytes, the sample could
not be run at a dilution factor of one. The flagged analyte concentrations is less than the blank UTL times the sample dilution
factor.
- Sample concentration was less than or equal to the blank UTL.
- Co-elution or interference was suspected.
- The recoveries of one or more of the internal standards were outside the applicable acceptance criteria. The X-nag indicates
which compounds were quantilated using the affected internal standard(s).
B
F
X
au 6 ROD, Final
3-12
January 1997
-------
Table 3.3-4
Summary of Surface Soil Analytical Results for Source LF04
Elmendorf AFB, AK
BacJcgrouDd Frequeocy of Locatioo of
Melbod ADalyt.e ACM Upper Maximum Deltctioa Muimam
(oils) Tolerance Resall lo'al bits!
Umil 10lal umDles Resalt
ladicalor Puamelers
SW9045 (pH unitS) InH - - 7.99 5/5 SS..Q46
D2216 (oerc(:nt) Percent moistUre - - 59.6 54/54 S5-023
SW8015ME'mlllkl!) Unidentified orlU\l\ics fUDROl 1000 - 2910 10/11 5S-003
SW8015MP i'mlllkl!) Unidentified orlU\l\ics rUGROl 500 - 3.6 B 4/11 MW~3
SW60IO (mslkg) Aluminum - 31183.96 22100 53/53 SS-021
Calcium - 8013.23 13400 53/53 5S-034
Iron - 43192.35 151000 53/53 SS-023
Maanesium - 10904.10 10900 53/53 SS..Q45
Potassium - 845.75 2830 53/53 SS-029
Sodium - 427.05 2280 53/53 SS-037
CODlamiDaol Puameters
5W8015ME (mRlkIl.) Diesel 1000 - 103 1/11 5S-002
5W8015MP '[J.lg/kS) Benzene 500 - 47.4 .4/11 S5-004
Ethylbenzene 50000 - 89.4 3/11 SS-005
Xvlene (tOIa\) 50000 - 315 8/11 5S-005
SW8240 (J.lglkg) Acetone - - 139 53/53 SS-024
2-ButanoneCMEK) - - 16.5 B 4/53 S5-024
Methylene chloride - - 83.2 X 30/53 SS-OI3
1,1,2,2. Tetrachloroethane - - 19.8 1/53 55-017
Toluene 50000 - 6.82 4/53 5S-032
Trichloroethene - - 11.3 1/53 5S-O 17
m & p.Xvlene 50000 - 5.46 1/53 MW-78
o-Xvlene 50000 - 2.11 1/53 MW.78
5W8080 (J.lSlkg) Aldrin - - 22.2 24/53 SS-O 14
alpha.BHC - - 1.22 II/53 SS-024
bela-BHC - - 9.44 P 2/53 SS..Q46
della-BHC - - 10.3 16/53 SS-039
gamma-BHC(Lindane) - - 31.3P 45/53 55-021
4,4'-DDD - - 8410 49/53 55-001
4,4'-DDE - - 1690 49/53 5S-00 I
4,4'-DDT - - 47300 50/53 SS-OOI
Dieldrin - - 143 P 19/53 SS-OOI
Endosulfan I - - 11.7 P 9/53 5S-038
Endosulfan II - - 4.88 3/53 SS-006
Endrin - - 22.6W 4/53 55-013
Endrin Aldehyde - - 5.32 10/53 SS-OI7
Heptachlor - - 8.44W 7/53 SS..Q40
Heplachlor eDOxide - - 23 16/53 S5-038
PCB-1254 - - 3120 1/53 SS-OI3
January 1997
3-13
OU 6 ROD, Final
-------
Table 3.3-4
(Continued)
Baeqrouad Frequeaey or Lac.doa or
Metbod Aa.lyk ACM Upper Maximum Dcttetioa MlSimum
(ualts) Toler.aee Result total bits!
Limit total sam Dies Result
SW8080 (Jlglkg) PCB-1260 - - 318 1/53 SS-040
I (continued)
SW8270 (mglkg) Benzo(a)anthrac:ene - ~ 0.23 6/53 SS-046
Benzo( a 1Dvrene - - 0.184 3/53 SS-046
BenzoCb )!luoranthene - - 0.466 F 3/53 SS-046
8enzolll.h.j)nervlene - - 0.24 2/53 SS-046
Benzo(k)!luoranthene - - 0.466 F 4/53 SS-046
Chrvsene - - 0.391 7/53 SS-046
Oibcnzofuran - - 0.0894 4/53 SS-021
1.4-0ichlorobcnzene - - 0.0349 1/53 SS-040
Oiethvlphthaiate - - 0.016 1/53 SS-038
bis{ 2-Ethvlhexvl)ohthalate - - 1.98 6/53 SS.oo7
Fluoranthene - - 0.345 7153 SS-046
Indeno( 1.2.3-<:d)Dvrene - - 0./51 2/53 SS-046
2-Methylnaphthalene - - 1.96 9/53 SS-OI4
4-MethylphenoV - - 0.0798 F 1/53 SS-040
3-Methvlphenol
Naphthalene - - 1.15 4/53 SS-OI4
Phenanthrene - - 0.3 9/53 SS-046
Pvrcne - - 0.516 7/53 SS-046
1.2.4- Trichlorobcnzcne - - 0.108 1/53 SS-040
SW8280 (Jlglkg) HDCDO Totals - - 11.7 6153 SS-013
HpCOF Totals - - 6.1 3/53 SS-OI3
HxCOO Totals - - 4.68 3/53 SS-038
HxCDF Totals - - 1.2 2/53 SS-OI3
OCOD - - 79.9 8/53 SS-OI3
OCDF - - 6.63 2/53 SS-OI3
PcCOO Totals - - 1.04 1/53 55-046
TCOO Totals - - 1.1 1153 SS-046
TCOF Totals - - 0.197 2/53 SS-039
5W6010 (mglkg) Antimony - NA 24.7 2/53 SS-046
Barium - 19645 1930 53/53 SS-OI3
Bervllium - 0.76 0.762 51153 5S-O 13
Cadmium - 2.68 6.96 6/53 SS-044
Chromium - 48.44 71.3 53/53 S5-046
Cobalt - 19.52 20.9 53/53 5S-023
Copper - 31.67 440 53/53 5S-037
Manlt8l1ese - 929.98 4640 53/53 S5-023
Molvbdenum - NA 6.52 34/53 SS-046
Nickel - 50.68 46 52/53 SS-038
Selenium - 0.54 11 4/53 SS-009
Silver - 1.68 4.74 39153 SS-037
OU 6 ROD, Final
3-14
January 1997
'C
-------
Table 3.3-4
(Continued)
B8Ckgroaad Frequeacy of Location of
MI~tbod Aaalyte ACM Upper Mnlmam Detectl08 Maxlmam
(uaits) Toleraate Renlt totaJ bltsl Result
Limit total sam Dies
SW6010 (mglkg) Thallium - NA 8.15 1/53 SS-046
(continued) Vanadium - 101.64 81.2 53153 SS-O 13
line - 90.01 757 52/53 SS-037
SW1060 (mRlb) Arsenic - 13.21 56.5 53153 SS-023
SW7421 (mRlkd Lead - 10.69 1160 53153 SS-031
ACM . AJlI.Ska Cleanup Malrix, level C.
B . Saml,le concenlration was less than or equal to the blank lITL.
F . Cc-elution or interference was suspected.
NA - NN applicable. -
p - Arlal)1e quantitation not confirmed. Results from primary and secondary GC columns differ by greater than a factor of three.
W - Due to the presence of PCB-I 260. it was not possible to quantitate this compound on the primary column. The unconfirmed result for the
stl:ondary column is reported.
- The recoveries of one or more of the internal standards were outside the applicable acceptance criteria. The X-nag indicates which
compounds were quantitated using the affected internal standard(s).
X
January 1997
3-15 .
OU 6 ROD, Final
-------
Table 3.3-5
Summary of Subsurface Soil Analytical Results for Source LF04
Elmendorf AFB, AK
Backgrouud Frcqacllcy or Loc.tiOIl or
Medaod (auits) Aualyte ACM Upper Mnimam DetcctioD Maximum
Tolenucc Result total bitsl
Umlt total ..mulcs Resalt
Judicator Par.meten
SW9045 (pH units) pH - - 83 10/10 SB-65
02216 locrcenH Percent moisture - - 26.2 26/26 SB-65
SW8015ME lmltJIuz) Unidentified orunics rUOR01 1000 - 189 11112 SB-65
SW8015MP (mltJkR) Unidentified orRanics rUGR01 500 - 14B 7/15 SB-65
SW60IO (mglkg) Aluminum - 18116.77 24700 12112 MW-77
Calcium - 10264.39 16400 12112 MW.77
Iron - 38483.64 35900 12112 MW-77
MalUlcsium - 14784.34 13200 12112 MW-77
Potassium - 1114.35 2090 12112 MW-77
Sodium - 365.59 414 12112 SB-65
Cout.mia.ut P.nmelen
SW8015ME (mRJIuz) Oicsel 1000 - 47.7 1112 SB-62
SW8015MP (pglkg) Benzene 500 - 694 5/15 MW-77
Ethylbcnzene 50000 - 32800 4/15 MW-63
Gasoline 500000 - 5880000 3/15 MW-63
Toluene 50000 - 14000 10/15 SB-62
X vlene /total) 50000 - 65900 9/15 SB-62
SW8240 (pglkg) Acetone - - 4660 14115 MW-63
2-ButanoncCMEK) - - 10.3 B 3/15 SB-65
Methvlene chloride - - 18.3 1115 SB-65
Srvrene - - 14.6 1115 SB-65
m & D-Xvlene - - 6920 5/15 MW-63
o-Xvlene - - 2470 4115 SB-62
SW8080 (pglkg) Aldrin - - II 4/12 SB-65
delta-BHC - - 17.6 P 1112 SB-65
Rarnma-BHC(Lindane) - - 3.06 7/12 MW-77
4,4'-000 - - 139 P 2/12 SB-65
4.4'-00E - - 294 1112 SB-65
4,4'-00T - - 177 3/12 SB-65
Heptachlor eDOxide - - 0.575 B 1112 MW-78
SW8270 (mglkg) Benzol a )anthracene - - 0.0213 F 1112 MW-77
Benzoic acid - - 2.14 1112 SB-65
Benzvl alcohol - - 4.3 1/12 SB-65
Butvlbcnzvlphthalate - - 0.0335 1/12 MW-63
Chrvsene - - 0.0351 1112 MW-77
Oibcnzofuran - - 0.019 1112 MW-77
Oiethvlphthalate - - 0183 1/12 MW-77
OimethvlDhthalate - - 0.0655 1/12 MW-77
OU 6 ROD, Final
3-16
January 1997
-------
Table 3.3-5
(Continued)
BlCkgrouDd' FrequeDcy of LOUtiOD or
Metllod (uDits) Aaalyte ACM Upper Maximum Detectioa Maximum
ToleRace Result total bits!
Umit total ..mDI~ Result
SW8270 (mg/kg) bisl2.E thvlhexvlmhthaJate - - 6.7 3/12 SB-65
(continued) Fluorene - - 0.0323 2/12 MW.77
2-Methvlnanhthalene - - 0.49 3/12 SB-62
2.Methvlnbenol (()-(:resol) - - 0.0439 1/12 SB-62
4-MethylphenoV, - - 0.0461 F Jl12 SB-62
3.Methvlnhenol
Nanhthalene - - 0.178 3/12 SB-62
Phenanthrene - - 0.105 2/12 MW.77
SW6010 (mg/kg) Barium - 95.93 411 12112 SB-65
Bervllium - 0.64 0.562 12112 MW-77
Chromium - 76.94 55.9 12/12 MW-63
Cobalt - 17.62 14.8 12/12 MW.77
Conner - 59.84 78.1 12112 MW-63
ManRanese - 709.45 709 12112 MW-77
Molvbdenum - - 9.68 10/12 MW-63
Nickel - 71.79 36.9 12/12 MW-77
Silver - 1.06 0.744 4/12 MW-77
Vanadium - 66.16 74.9 12112 MW-77
Zinc - 76.17 77.8 12112 MW.77
SW7060 (rnIVkR) Arsenic - 9.31 11.3 12112 MW-77
SW7421 (rnlllkll) Lead - 10.13 11.2 12112 SB-65
ACM . Alaska Cleanup Matrix, level C
B - Samille concentration was less than or equal to the blank UTl.
F - Co-elution or interference was suspected.
P .' Analyte quantitalion not confinned. Results fTom primary and secondary GC columns differ by greater than a factor of three.
January 19'97
3-17
au 6 ROD, Final
-------
Indicator parameters primarily include metals classified as nutrients, and non-speciated fuel constituents
such as unidentified diesel range organics (UDRO) which are unsuitable for use in a risk assessment. A
detailed discussion of the determination of the COCs for LF04 is presented in Section 3.3.3.
Groundwater Contamination at LF04
Groundwater data at LF04 was characterized as three separate groups, based upon the
hydrogeology at the site. As discussed in Section 3.1, several different aquifers occur at LF04, in
addition to groundwater seeps. The groundwater data were separated into groundwater data on the bluff
(which combines the first two aquifers encountered) (Table 3.3-1), groundwater data from the beach
(water from the third aquifer) (Table 3.3-2), and groundwater seep data (Table 3.3-3). The predominant
types of groundwater contamination detected at LF04 include volatile organic compounds (VOCs),
BTEX constituents, fuels, metals, and pesticides. In general, the most contaminated hydrogeologic
regime was the bluff, where benzene concentrations were recorded at a maximum of 3400 J.lg/L in a
sample from MW-6l (Table 3.3-1). Other BTEX constituents were also elevated in samples from that
well and MW-77. Additionally, 2.28 inches of free phase floating product was found at MW-77 during a
1995 field investigation. In addition to BTEX, elevated levels of heavier hydrocarbons, such as SVOCs
were detected, as well as low levels of solvents and pesticides. Constituents in these groups were
generally detected less frequently in the bluff groundwater than BTEX constituents and were at
significantly lower concentrations. Locations for all remedial investigation soil and groundwater
sampling points within LF04 are presented in Section 3.3.3.
Numerous metals were also detected in the bluff groundwater at LF04. These include
relatively low concentrations of barium, beryllium, cadmium, chromium, cobalt, copper, manganese,
nickel, selenium, vanadium, and zinc (Table 3.3-1). As atWPl4, a comparison of these metals
concentrations was made to available background metals concentration from the Elmendorf Air Force
Base. Alaska: Basewide Background Sampling Report (USAF, 1993b). Based on a comparison between
mean background confidence intervals and mean LF04 metals data, all metals in the bluff groundwater at
LF04 were determined to be at or near background concentrations. The summary statistics for the USGS
data, including the upper confidence limit concentrations used for these comparisons, are presented in
Table 2.3-4.
In the groundwater data collected along the beach at LF04, VOCs, including benzene,
were significantly lowerthan those on the bluff (Table 3.3-2). A notable exception to this was the
occurrence of speciated jet fuel and gasoline, which were not detected in the bluff groundwater.
Gasoline was detected in the beach aquifer at 5160 J.lg/L in a sample from well K-304. Pesticides,
SVOCs, and other heavy hydrocarbons were also identified in the beach groundwater, but as on the bluff,
these constituents were detected rather infrequently and at relatively low concentrations. Based upon a
statistical comparison to the USGS background data, all metals detected in the beach groundwater at
LF04 were determined to be at or near background concentrations.
Seep data at LF04 indicates contamination of seep water predominantly by BTEX
constituents and fuels. Benzene was reported at a maximum concentration of289 J.lg/L in the sample
from seep SP-02. Elevated fuels were also reported occurring at this seep, with gasoline reaching a
maximum of9l50 J.lgIL. Ofthe contaminant parameters detected, most occurred at this seep
(Table 3.3-3). In addition to fuels constituents, other volatile organic compounds were detected, as were
SVOCs, and polynuclear aromatic hydrocarbons (PAHs). These constituents occurred at low levels, and
in statistically few samples. No pesticides were detected in the beach groundwater. Metals were
detected, but these were determined to be at or near background levels.
OU 6 ROD, Final
3-18
January 1997
-------
Soil Contamination at LF04
Soil data from LF04 were evaluated based upon surface and subsurface contaminant
occurrences. Surface soils include all soils collected from depths shallower than 3 feet bgs. Subsurface
soils are those collected from below 3 feet. Tables 3.3-4 and 3.3-5 list the sample depths, maximum
concentratiions, locations, and guidelines associated with the ACM for non-UST soil for all contaminant
parameters, in the surface and subsurface soil samples at LF04. Results below the detection limits are not
included in the analytical summary tables.
Contamination in the soils at LF04 consists primarily of fuels, weathered fuel residuals,
pesticides, metals and dioxins. BTEX constituents were detected in both surface and subsurface soils.
The maximum BTEX occurrence in the surface soils was detected for xylene at SS-005 at 315 ~g/k.g.
Pesticides, such as 4,4'-000 and 4,4'-00T, were detected frequently in the surface soils at LF04,
however the average concentrations of these constituents was low. Isolated occurrences of elevated
concentratiions along roadways are indicative of residual pesticides from surface applications rather than
pesticides occurring as the result of an undocumented release. Numerous dioxins were also detected in
the surface soils at LF04, particularly in the soils on the beach. The dioxins occur at very low levels, and
appear to be the result of the incomplete burning of wastes within the bluff landfill.
The contaminant levels in the subsurface soils exceeded those of the surface soils at
LF04. Most of the elevated volatile constituents in the subsurface soils are associated with smear zone
contamination near the water table. The maximum BTEX occurrence in the subsurface soils at LF04 was
xylene at 65,900 ~glkg in a soil sample from boring SB-62. Pesticides and SVOCs occurred at
significantly lower concentrations in both surface and subsurface soils than fuel constituents. Dioxins
were not identified in subsurface soils (Table 3.3-5). The soil COCs for LF04 are presented in
Section 3.3.3.
Metals were identified in both surface and subsurface soils at LF04. The metals detected
were determined to be predominantly at or near background concentrations. The background results
used in the metals evaluation at LF04 are included in the soil analytical tables (Tables 3.3-4 and 3.3-5).
Analytical results from the basewide background sampling event (USAF, 1993) were pooled into surface
and subsurface soil results, and were used as the basis to conduct statistical comparisons with on-site
results.
3.3.2
Risk Evaluation
Based on the concentrations of contaminants detected during the RI, human health and
environmental risk assessments were performed to determine if areas should be considered for remedial
action. All concentrations of contaminants. including all contaminants of concern, whether exceeding
MCLs or ACM guidelines or not. were included in the risk assessments. The general discussion of the
human hecLlth and ecological risk assessment procedures is presented in Section 2.3.2, and will not be
repeated s:ince the procedures for each of the source areas within OU 6 were identical. Details on the
parameters used in the Health Risk Assessment are shown on Table 2.3-5.
Human Health Risk Assessment (lIRA)
Since LF04 is not currently used residentially, a current residential risk scenario was not
evaluated, and only current visitor and trench worker scenarios were applied. Even though the future
land use alt LF04 is restricted as specified in the Base Comprehensive Plan, thejuture residential risk
scenario was evaluated to obtain the most conservative risk information possible.
January 1997
3-19
OU 6 ROD, Final
-------
ELCRs and HIs were calculated to describe cancer and noncancer risks, respectively.
The ELCR is the additional chance that an individual exposed to site contamination will develop cancer
during his/her lifetime. It is expressed as a probability such as I.OE-06 (one in a million). The HI
estimates the likelihood that exposure to the contamination will cause some negative health effect. An
HI score above one indicates that some people exposed to the contamination may experience at least one
negative health effect.
The calculated risks at LF04 are based on hypothetical exposure to soil and groundwater.
Groundwater risk at LF04 was calculated separately for the bluff and the beach, since these two areas
were distinct geographically and had differing types and concentrations of contaminants. The shallow
groundwater aquifers at LF04 are not presently used and will not be used in the future for supplying
potable or non-potable water. For carcinogenic soil risk, the calculated results for the future resident
reasonable maximum exposure (RME), construction worker, and visitor are listed. Only the future
resident scenario (RME) was used to calculate carcinogenic groundwater risk. Table 3.3-6 summarizes
the calculated carcinogenic and noncarcinogenic human health risks calculated for LF04.
Groundwater carcinogenic risk at the bluff for the residential scenario (RME) exceeded
1.0E-03. Benzene is the predominant risk driver, with several other constituents, primarily solvents and
pesticides, driving the risk. This risk is consistent with that identified for the groundwater at WP14,
further supporting the conclusion that the aquifers in these locations are interconnected.
I ,2-Dichloroethane and toluene are the primary contributor to theRME noncarcinogenic risk, which
exceeded an acceptable HI of 1.0. Beach groundwater RME risk was moderately elevated at 1.7E-05.
As for the bluff groundwater, solvents, pesticides and benzene were the primary beach risk contributors.
The noncarcinogenic risk for the beach groundwater was at an acceptable level (Table 3.3-6).
Shallow soil carcinogenic RME risk at the LF04 beach and bluff were at similar levels,
near I.OE-05. The visitor scenario risk also slightly exceeded I.OE-06 for both areas. The
. noncarcinogenic risk for RME soils in both areas exceeded 1.0. Risk to trench workers from subsurface
soil is at an acceptable level. Bluff soil risk was attributable to metals, pesticide and dioxin
contamination. Bluff soil risk was caused by metals and dioxins only.
Ecological Risk Assessment (ERA)
The ERA was performed to determine if the reported concentrations of chemicals or
calculated exposures to plants and wildlife at OU 6 are likely to produce adverse effects. Ecological
effects were evaluated quantitatively by calculating Ecological Quotients (EQs). The ERA focused on
evaluating potential impacts of the contamination on selected indicator species: the moose, masked
shrew, meadow vole, black-capped chickadee, merlin, and peregrine falcon. The spotted sandpiper was
also identified as an indicator species for evaluating ecological risk on the beach. The general discussion
of the ecological risk assessment procedures is presented in Section 2.3.2 and will not be repeated since
the procedures for each of the source areas within OU 6 were identical.
Calculated EQs for the bluff soils exceeded 1.0 for small animals due to concentrations
of barium, lead, benzo(a)anthracene, and seven pesticides. The highest EQ was associated with barium
and equals 8300 for the black capped chickadee. This is followed by lead, which has anEQ of 4600, also
for the black capped chickadee. EQs on the beach soils also exceeded 1.0 due to copper, lead and zinc
concentrations for small animals, as well as numerous pesticides and SVOCs. The highest EQs are
associated with lead for the black capped chickadee, masked shrew and spotted sandpiper (24,000, 7400,
and 3800, respectively) and with 4,4'-00E (3800), also for !he spotted sandpiper. EQs were calculated
OU 6 ROD, Final
3-20
January 1997
-------
Table 3.3-6
Summary of Human Health Risks at LF04
Elmendorf AFB, AK
Surface Soil (<3 feet) Subsurface Soil
Risk Residential Visitor Trench Cbemical(s) Driving
Risk
Scenario. Scenariob Worker Scenario.
Soil Risk Beachd
Carcinogc~nic 4.4E-05 2.7E-06 NA Arsenic, HxCDD, TCDF,
HpCDD
Non-Carcinogenic 2.78 0.14 NA Arsenic, Manganese
Soil Risk Bluff"
Carcinoge~nic 2.8E-05 1.7E-06 <1.0E-06 Arsenic, 4,4'-DDT,
HpCDD
Non-Carcinogenic 4.0 0.2 NR Arsenic, 4,4'-DDT,
Manganese
Groundwater Risk Beachd
Carcinogenic 1.7E-05 NA NA Benzene, Heptachlor
epoxide, Dieldrin, Aldrm,
1, I ,2,2- Tetrachloroethane,
Vinyl Chloride
Non-Carcinogenic <0.1 NA NA None
Groundwater Risk Bluff"
Carcinogenic 2.6E-03 NA NA Benzene,
1,2 - Dich loroethane,
Methylene Chloride, Vinyl
Chloride, Chloromethane,
Aldrin, Dieldrin,
Alpha-BHC
Non-Carcinogenic 2.4 NA NA 1,2 - Dichloroethane,
Methylene Chloride,
Aldrin, Dieldrin, Toluene,
Ethylbenzene
Bluff Seeps
NR Only evaluated for visitor scenario. No significant risks identified.
. Excess cancc~r risks conservatively assumed for 30 years of exposure (drinking groundwater, contact with soil, etc.) by future residents
(Reasonable Maximum Exposure).
. Excess cancc:r risks conservatively assumed for 30 years of exposure while visiting the site under current conditions.
< Excess cancc:r risks conservatively assumed for I year of exposure during on-site construction work (digging, etc.).
J Risks are cakulated by using the 95% upper confidence limits (UCLs) for contaminants present unless the 95% UCL exceeded the maximum
concentration detected. in which case the maximum concentration was used. This represents a conservative estimate of the "worst case"
contamination.
NA - Not applicable.
NR - Significant risk not identified.
January 1997
3-21
au 6 ROD, Final
-------
based on surface soil and seep contaminant concentrations. None of the calculated EQs exceeded 1.0 for
the moose, peregrine falcon, or merlin at LF04.
The sandpiper had the most EQ exceedances for constituents in the beach soils, some
exceedances being substantial. It should be noted that sandpipers are infrequent users of the beach, and
that their period of occupancy is only a maximum of about 5 months. This 5 month occupancy factor
was incorporated into the exposure evaluation.
Uncertainties Associated with the Risk Assessment
The major assumptions and uncertainty factors for the au 6 human health and
ecological risk assessments are presented in Section 2.3.2.
3.3.3
Conclusions
. The following subsections provide a discussion of the determination ofCOCs for LF04,
the location and extent of contamination by cacs in excess of preliminary remediation goals, and a
summary statement about the risk to public health, welfare, or the environment if action is not taken at
LF04.
Contaminants of Concern
Constituents exceeding preliminary remediation goals (MCLs for groundwater, ACM
guidelines for soils) were identified in the Proposed Plan. COCs were developed from the results of the
risk assessment and by considering preliminary remediation goals. Each constituent having an individual
contribution of greater than I.OE-06 carcinogenic (RME) risk, or an HI greater than 0.1 when the
cumulative number for the site is greater than 1.0, was considered as a cae. In addition, any constituent
exceeding preliminary remediation goals (MCLs for groundwater or ACM guidelines for soil) was also
considered as a cae. The final cacs for LF04 are shown on Table 3.3- 7, with the individual risk
contributed and basis for identifying the cac (risk or regulatory standard).
Five cacs were identified for groundwater at LF04: benzene; ethylbenzene; toluene;
1,2-dichloroethane; and methylene chloride (Table 3.3-7). These constituents contributed to a broad
plume of contamination in the groundwater at LF04 (and WPI4), which was originally presented for
fuels as Figure 2.3-1. The estimated volume of this plume is 45.5 million gallons. A second map,
depicting the plume of chlorinated species at LF04, is presented as Figure 3.3-1. Since chlorinated
solvents were not cacs at WPI4, this map is limited to the LF04 area only. The estimated volume of
the chlorinated solvent plume is 17.7 million gallons. Both plumes are drawn based upon concentrations
exceeding 5 J.lg/L, which is the MCL for benzene and 1,2-dichloroethane.
The groundwater fuel plume at LF04 encompasses most of the southern portion of LF04
(LF04 South). The solvent plume is not as pervasive, being limited to an area in the center ofLF04
South. Because the groundwater cacs at LF04 are found exclusively in the southern portion of the
source area, LF04 was divided into LF04 South and LF04 North for the purposes of the evaluation and
selection of groundwater remedial alternatives. This convention is followed in Sections 3.4 and 3.5.
The Proposed Plan identified three additional groundwater constituents as exceeding
their regulatory levels: bis(2-ethylhexyl)phthalate, cadmium, and selenium. Three other metals,
chromium, nickel, and arsenic, also exceeded MCLs. Bis(2-Ethylhexyl)phthalate was not identified as a
cac, because detection of this compound was associated with sampling in the presence of fuel and not
with historic land uses. The five metals were not identified as cacs because: (I) their identification as
au 6 ROD, Final
3-22
January 1997
-------
o
.c
110\
~
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!.
'-
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::s
c::
I»
~
Table 3.3-7
\C
'"
....:a
Summary or Contaminants or Concern I at LF04
Elmendorr AFB, AK
IN
I
IV
IN
Chemical Maximum Maximum Cancer Maximum Hazard Basis for COC Remediation Uasis for
Concentration Risk Index Goal Remediation Goal
Groundwater:
Iknicne 3400 IIg/L 1.4E-03 -- Exceeds MC!.; contributes 511g1L MC!.
to a risk> I.OE.06
Ethylbenzene 722 IlglL .- 0.43 Exceeds MC!.; contributes 700 J.1g/L MC!.
to III > I
Toluene 3020 J.1g/L -. 0.67 Exceeds MCL; contributes 1000 J.1g/L MCI.
toHI> I
I ,2-0ichloroethane 38.7 J.1g1L 3.7E.05 1.2 Exceeds MCL; contributes 5 IIg/L MCL
10 a risk> I.OE-06;
wnlributcs to III >1
Methylene chloride 290 J.1g1L 6.JE-06 <0.1 Exceeds MCL; contributes 5 ~tglL MCL
to a risk> I.OE-06
Shallow Soils (0-5 feet bgs):
Exposed landfill .. .. -- Alaska solid waste .- --
waste regulations
Deep Soils (>5 feet bgs): (No CDCs for Deep Soils)
1 Cancer risk:!: I.OE-06 or III :!: 0.1 lor soil or groundwater scenario with 8 tol81111 of:!: 1.0; or concentrations lound in excess of regulatory levels. If cancer risk or III did not exceed standards, it
was marked as "..".
bgs - Below ground surface
COC . Contaminant of Concern
MCL . Maximum Contaminant Level (40 CFR ~ 141.61 for Federal MCLs; 18 AAC 80.070 lor State MCLs). Federal and State MCLs arc identical lor the COCs.
-------
o
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. I} q-'rl )' \ rnUF~,.';~ \ ~" '~--.",:'._~~:'~' M~XING -;~~h--' -- .
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/ I I! I' \ I \ ' . \" r~\~::~ . ,.- /-- 2l:j
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INST ALL A nON . I . t.. 1"'- ._.:.J SpL04) . , ". " ,..-.
BOUNDARY---, . I --==t~-- '~. ., '; ,-' ,SOURCE WP14
ORIGINAL LF04 "(: ~ t~'.~" ~.'~2it '/:', / { '. "~~';," i /
BOUNDARY --, , . r- ~r:e~---t ,J' \ \\.,' / .':..
~ . '-! .- _.~'n,7/ ", ,',:' / . '7. i
\: {I' \ . - - I "-\>', ' . " '" I " ;
~ ./. ~IA,8.._, " ( \ . 'r/; , /.. -77 '-- ,/1
.* . I \~, n t: JI. ). ., :<~'r" . ~, /f[(\ /
~ :1 ),~ ,,:.- ' . ," ,',">~~ : : '/' .:~ IIW-05S".<.~: ,,/"'- ~
. \ ", -, '! I .' / /. , MW.. 12 / /,// / ,SS
" I." ..! ",'" --"":\', S ",/' ','2
,: ~ ' f': ' . '}, ' :~ ,/ -,-~. >-./ /. > . /
LF04 NORTH/ "I..!/_//'" / /;--,-, "';'...' " /".-'" .:=, ,-- - _.~:.: ': . C ..
AND BEACH-'-(., \ I~ . /'.. (i --i'/I< . '-"::~
.
-~ '" '-""-~').( ".», - --- -"~==-
It\ill - \ . '<:.::.~>;/ //.':f7}-;d~/ -"""',
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" I \ ". .-: / ~~
( IIW-8 -f / //.~':-)" 7 :'
1- "" \ ffj( - I / ~ r--"I-~/
!) I ,- '~'J..O} / ~, 'n -. 'I 1(""" LF04 SOUTH
j ... -,f: .' #" 'I
fj--" K-.!O. ( . f+'1/ /~VA,..,~/'~"30 1\, '
j: . \P,OI ;::-' '. ,;.5. I.IW-74 \
-. .' 1/, '-IIW-63 \,
I I' r \'il; " '\
I I I' I /1/11 .. \
/ . I I~' :jJ L,
-_.-::-._-:./ I.!...}:{~::., .-.----
MIXING ZONE
. -._--- -
.' -
-- -.-:-
I
--
N 0 rt h
~
IIW-60
!'.;
IIW-O:!
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,
IV
~
,/--,- '-::~:~:~:
-.-.-'.
\
IoIW-15
----- ..- -..-.------ --..
ELMENDORF AFB
LEGEND
~
~onlto( Well locatio"
c"."\
Seepage Location
c.:----
""/~
{;' Chlorinaled VOC Plume Addressed jn rs
@J lAiling lone
- - - - HO. Sou," Boundary
- - - - Or;gil\Ol lro. Boundary
WP" Boundary
....
~
C
~
- - - Pipeline
- Installation Boundary
SCALE
o 150
l_---r.,t ---,
~
..
~
o
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..
~
--.." .---.----.-------
..--
Figure 3.3-1. Chlorinated Solvent Plume in the Groundwater at LF04
-------
a COC would have been based entirely on total metals results for turbid samples with corresponding low
concentrations in the dissolved phase; and (2) their concentrations did not contribute to significant health
risks. Metals at LF04 were also not identified as COCs because their concentrations were comparable to
background levels. Additionally, pesticides and 'dioxins were not included as COCs because these
constituell1ts did not significantly contribute to risk.
The Proposed Plan listed ORO, ORO, benzene, and BTEX as soil contaminants with
concentraltions that exceeded cleanup levels. One area of soil contamination near the pumphouse was
addressed as a Compliance project. Tank 790 near the pumphouse at LF04 South (Building 30-790) and
the associiated contaminated soils were excavated in f\1ay 1996. Additionally, the POL line that borders
LF04 has been named as a new CERCLA site and will therefore be addressed as a separate project. The
remaining areas contained fuel-related contamination in the smear zone which will be addressed as part
of the groundwater remedy (see Section 2.3.3).
Pesticides and dioxins were also detected in the soils at LF04. These constituents were
not identified as COCs because their contribution to health risk was insignificant. Metals were
indentified in the soils at LF04, but they were not indentified as COCs because: (I) their contribution to
health rislk was insignificant; and (2) their concentration was comparable to background levels. Thus, no
chemical.,specific COCs were identified for LF04 shallow or deep soils.
Uncovered landfill waste at LF04, particularly debris that has fallen onto the beach, was
identified as requiring a response action as part of the remedy for LF04. Debris such as old containers,
automotive parts, crushed drums, old piping, etc., are believed to represent a threat to human health or
, the environment. As a consequence, exposed waste is listed as a COC for the shallow soils at LF04.
Since the exposed waste at LF04 is limited to debris on the beach, the north and south division of LF04
was modified such that LF04 North includes the entire beach front (LF04 North/Beach), and LF04 South
is limited to the bluff in the southern portion of LF04 only. Accessible debris on the LF04 South bluff
face will also be treated the same as the LF04 NorthlBeach area. This was done to prevent unnecessary
duplication of evaluation of alternatives for the landfill waste in both LF04 North and LF04 South. The
area of e>l:posed and accessible landfill waste is estimated to be 20 acres.
Summary
Actual or threatened releases of hazardous substances from LF04, if not addressed by
implementing the response action selected in this ROD, may present an imminent and substantial
endangenment to public health, welfare, or the environment.
3.4
Remedial Action Objectives. Alternatives. and Comparative Analysis for LF04
The following subsections discuss the remedial action objectives for LF04, and present a
description of the various alternatives which were evaluated to achieve those remedial objectives. The
results of the detailed comparison made between those alternatives are also presented. As discussed in
Section 3.3, LF04 is divided into two areas, LF04 South and LF04 North/Beach.
3.4.1
Remedial Action Objectives
Specific remediation alternatives were developed and evaluated for the areas with
potential risk and that exceeded the preliminary remediation goals identified in Section 3.3.3. Specific
remedial action objectives (RAOs) for LF04 are as follows:
,January 1997
3-25
OU 6 ROD, Final
-------
For LF04 South (bluff groundwater):
.
Prevent the ingestion, dennal contact, and inhalation of vapors from'groundwater having
benzene; toluene; ethylbenzene; 1,2-dichloroethane; and methylene chloride in excess of
MCLs and/or resulting in a cancer risk greater than 1.0E-06 or Hazard Index greater than
1.0.
For LF04 North/Beach (beach soils):
.
Mitigate human dennal exposure, to the extent practicable, to landfill waste or debris.
.
Mitigate exposure, to the extent practicable, of environmentally sensitive receptors to
landfill waste. Relevant exposure pathways for wildlife include incidental ingestion of
contaminated soil, ingestion of contaminated vegetation, and ingestion of contaminated
animals (e.g., insects and earthwonns).
As discussed in Section 3.3.3, the soil at LF04 South and the groundwater in LF04 North/Beach have no
COCs; thus, RAOs were not developed for these areas.
Groundwater Alternatives
As discussed in Sections 3.3.3 and 3.4.1, the bluff groundwater (north of MW-K302) and
the beach groundwater do not have any COCs or RAOs. Thus, alternatives were not developed for the
LF04 NorthlBeach groundwater.
3.4.2
As discussed in Section 3.3.3, the primary COCs are HVOCs and fuel constituents in the
LF04 South groundwater. In the OU 6 RIfFS, the contaminated groundwater at LF04 South was grouped
with the contaminated groundwater at WP14 because: (1) groundwater from WP14 flows directly into
LF04 South; (2) the groundwater contains similar COCs; and (3) LF04 South is Of) an unstable bluff so
any extraction wells for this area must be installed upgradient of LF04 South (i.e., on the border between
WP14 and LF04 South). Thus, Section 2.4.2 discusses the groundwater alternatives for both WP14 and
LF04 South.
3.4.3
Summary of Comparative Analysis of Groundwater Alternatives
The comparative analysis describes how each of the groundwater alternatives meet the
CERCLA evaluation criteria relative to each other. This analysis is discussed in Section 2.4.3 for both
WP 14 and LF04 South.
3.4.4
Soil Alternatives
The soil at LF04 South (south of MW-KJ02) does not have any COCs or RAOs
(Sections 3.3.3 and 3.4.1); therefore, alternatives were not developed for this area. As discussed in
Section 3.3.3, the only COC for LF04 North/Beach soils is the exposed landfill waste. Only two
alternatives were evaluated: no action, and annual removal of beach debris.
Alternative SI: No Action
Evaluation of this alternative is required by CERCLA as a baseline reflecting current
conditions without any cleanup. This alternative is used for comparison with each of the other
alternatives. This alternative does not include long-tenn monitoring, controls, or access restrictions;
therefore, potential exposure pathways would not be eliminated. There are no costs associated with this
alternative.
OU 6 ROD, Final
3-26
January 1997
'<
-------
Alternative S2: Annual Removal of Beach Debris
This alternative includes removing debris that has fallen to the foot of the bluff, or other
loose debris which could be collected without impacting the stability of the bluff slope from areas
accessible to the necessary equipment. If hazardous materials are encountered during the annual removal
events, these materials will be handled appropriately.
Additionally, access to soil would be institutionally controlled. LF04 is currently
designated as a "restricted use area" in the Base Comprehensive Plan. This designation provides for
recreational use of the parcel (cross country skiing, etc.) and for construction of unmanned facilities such
as a parking lot, storage building, or taxiway, but prohibits the construction of any sort of manned facility
such as an office building or a residence. As a former landfill, LF04 will maintain this designation
indefinitely.
The cost for Alternative S2 is $12,200 for the initial beach sweep and about $9700 for
each subsequent beach sweep. The present worth cost for 30 years of removing beach debris is
$162,000. The actual remediation time is indefinite. Thirty years of removal was costed, per CERCLA
guidance:.
3.4.5
Summary of Comparative Analysis of Soil Alternatives
Annual removal of beach debris is considered to be the sole practicable remedy. A
variety of other alternatives were considered to address the exposed landfill material on the beach, such
as capping or stabilization. However, due to the instability of the bluff slope, the overall size of the
landfill 2lrea, and the fact that tidal action will continually cause slope erosion, remedial actions such as
slope capping, excavation, and stabilization were considered impracticable. Annual removal of the
landfill debris was considered protective of the human health and the environment since it would prevent
the accumulation of excessive debris on the beach and would reduce the chances of contact between the
debris and humans or animals. The risks are low at the LF04 beach because of the remoteness of the site
and lack receptors.
Annual removal of beach debris is also the best alternative for long-term effectiveness
and pem)anence as well as short-term effectiveness. This alternative would reduce risk to human health
and the c;:nvironment by removing the debris without damaging the stability of the bluff. The risks to on-
site workers would be minimal. Additionally, this alternative reduces toxicity, mobility, and volume of
the debris by removing it from the site and recycling the metal debris. .
Overall, removal of beach debris is considered the sole practicable remedy, pecause all
. other options would allow the site conditions to deteriorate (e.g., no action) or would not be
implementable or cost effective (e.g., capping, stabilization, or excavation). Thus, removal of beach
debris is the most implementable alternative and the most cost-effective action ($162,000).
One ARAR identified for the soils at LF04 is the Alaska Solid Waste Management
Regulations, Closure Standards for Municipal Solid Waste Landfills (18 AAC 60.390). To address the
final cover requirement of this regulation, the present cover of soil and vegetation, along with annual
debris removal, has been approved by ADEC. There is no benefit to the additiof! of more cover to this
site, because the additional weight of the soil would increase the potential for landslides on the bluff.
Furthermore, adding cover to the beach soils would be futile, because transport of sand caused by the
tides and! waves would erode the cover soil as the beach re-establishes an equilibrium with sea level.
January 1997
3-27
OU 6 ROD, Final
-------
The other ARAR identified for LF04 is the off~site disposal rule (40 CFR 9 300.440).
Any hazardous substances, pollutants, or contaminants identified during the debris removal would be
disposed of in accordance with this regulation. Thus, Alternative S2 complies with all ARARs.
Selected Remedy for LF04
The selected remedy for LF04 South groundwater is Alternative G2 (long-term
monitoring of groundwater with institutional controls and product removal). The selection process and
benefits for this alternative are discussed in Section 2.5.
3.5
As discussed in Section 3.3.3 and 3.4.1, LF04 NorthlBeach groundwater does not have
any COCs or RAOs~ therefore, no alternatives were evaluated. Additionally, no COCs or RAOs were
listed for LF04 South soils, and no alternatives were evaluated. Thus, LF04 NorthlBeach groundwater
and LF04 South soils are recommended for No Further Action.
The selected remedy for LF04 NorthlBeach soil is annual removal of beach debris
("'beach sweeps"). This alternative is the sole practical remedy for mitigating exposure to landfill waste,
because it removes the majority ofthe exposed waste without impacting the stability of the bluff. It is
also acceptable to the public and the State of Alaska. .
Specific components of the selected remedy are illustrated in Figure 2.5-1 in Section 2.5,
and consist of the following: .
Groundwater at LF04 NorthlBeacb:
.
No further action is required for the groundwater at LF04 NorthlBeach.
Groundwater at LF04 Soutb:
.
Access to groundwater at LF04 South will be institutionally controlled. LF04 is
currently designated as a "restricted use area" in the Base Comprehensive Plan. This
designation provides for recreational use of the parcel (cross country skiing, etc.) and for
construction of unmanned facilities such as a parking lot, storage building, or taxiway,
but prohibits the construction of any sort of manned facility such as an office building or
a residence. Drilling into the shallow aquifer is also restricted by the Base
Comprehensive Plan. As a former landfill, LF04 will maintain this designation
indefinitely.
.
Groundwater will be monitored and evaluated annually to determine contaminant
migration and to track the progress of contaminant degradation and dispersion, as well as
to provide an early indication of unforseen environmental or human health risk. Five-
year reviews will also assess the protectiveness of the remedial action, including an
evaluation of any changed site conditions, as long as contamination remains above
cleanup levels.
.
Recoverable quantities of free product found on top of the water table at LF04 will be
regularly removed during groundwater monitoring events.
3-28
January 1997
OU 6 ROD, Final
-------
.
Groundwater monitoring will be discontinued if contaminant levels are below cleanup
levels during two consecutive monitoring events. In that case, no further action for
groundwater will be required. .
.
During the final round of monitoring, samples will be collected and analyzed for all
constituents that exceeded MCLs during the 1994 investigation including VOCs,
SVOCs, and metals. These results will be evaluated before a final determination is made
that groundwater meets all cleanup requirements.
.
All groundwater is expected to be cleaned up within 14 years.
Soil at LF04 NortblBeach:
.
Access to soil at LF04 NorthlBeach will be institutionally controlled. LF04 is currently
designated as a "restricted use area" in the Base Comprehensive Plan. This designation
provides for recreational use of the parcel (cross country skiing, etc.) and for
construction of unmanned facilities such as a parking lot, storage building, or taXiway,
but prohibits the construction of any sort of manned facility such as an office building or
a residence. As a former landfill, LF04 will maintain this designation indefinitely.
.
No further action is required for soil contamination at LF04 NorthlBeach; however,
landfill debris on the beach from LF04 will be removed annually as the specific remedy
for this area.
.
The removal of debris will include all LF04 landfill material which has fallen onto the
beach which can be reasonably collected for disposal, as well as debris on the bluff slope
or other low lying areas which can be accessed and removed without hazard.
.
Hazardous materials encountered during the annual removal events will be handled
acc.ording to appropriate regulations.
.
The removal of debris from the beach at LF04 is expected to continue annually for 30
years or as long as the landfill remains subject to erosional action by tides. Five-year
reviews will assess the protectiveness of the remedial action, including an evaluation of
any changed site conditions.
.
No further action will be required as a means of closing the LF04 landfill.
Soil at LF04 South:
.
No further action is required for the soil at LF04 South.
The estimated time for groundwater cleanup is 14 years. Groundwater will be monitored
to evaluatt: the progress of degradation and dispersion. Further response actions, coordinated with the
regulatory agencies, may be considered if monitoring finds unacceptable contaminant migration or
unacceptable reduction in contaminant concentrations.
The duration of the soil remedy is indefinite. The cost estimate includes 30 years of
annual beach sweeps, per CERCLA guidance. Further response actions, coordinated with the !egulatory .
January 1997
3-29
OU 6 ROD, Fini1!
-------
agencies, may be considered if additional contamination is discovered during the annual beach sweeps or
if the degree of reduction of debris on the beach is unacceptable. .
Because the remedy will result in contaminants remaining on-site, a review will be
conducted within 5 years after commencement of remedial action. The review will ensure that the
remedy continues to provide adequate protection of human health and the environment. The
groundwater cleanup levels (i.e., remediation goals) to be achieved at LF04 are presented in Table 2.5-1.
The selected remedy includes provisions for the preparation of a workplan for continued
environmental monitoring of the affected media. This workplan will include specific details regarding
the number and location of monitoring points and what will be monitored for, as well as guidelines for
eliminating select monitoring points as cleanup occurs. Environmental monitoring will be discontinued
at LF04 when the remediation goals have been satisfactorily achieved (Table 2.5-1). This determination
will be made jointly by the USAF, the USEPA, and the State of Alaska pursuant to the Federal Facility
Agreement.
3.5.1
Statutory Determinations
The selected remedy satisfies the requirements under Section 121 of CERCLA to:
.
Protect human health and the environment;
.
Comply with ARARs;
.
Be cost effective; and
.
Utilize permanent solutions and alternative treatment technologies to the maximum
extent practicable.
Section 2.5.1 discusses how Alternative G2 meets the CERCLA requirements. The following
subsections discuss how the beach sweeps satisfy the CERCLA requirements for the LF04 NorthlBeach
soils.
Protective of Human Health and the Environment
The selected remedy is protective of human health and the environment. The current
risk to human health from the exposed landfill waste is minimal and will be further reduced by removing
the waste. Additionally, removal of the debris will protect the environment by preventing it from
migrating to Knik Arm.
Applicable or Relevant and Appropriate Requirements (ARARs)
Chemical-Specific AR.ARs - There are no chemical-specific ARARs which must be
met for the LF04 NorthlBeach soils.
Location-Specific ARARs - There are no specific ARA~ which must be met because
of the location of the contamination and remedial actions at LF04.
Action-Specific ARARs - The Alaska Solid Waste Management Regulations, Closure
Standards for Municipal Solid Waste Landfills (18 AAC 60.390) are relevant and appropriate regulations
. for LF04. To address the final cover requirements of this regulation, the present cover of soil and
au 6 ROD, Final
3-30
January 1997
-------
vegetation, along with annual debris removal, is approved by ADEC. As discussed in Section 3.4.5 there
is no benelfit to the addition of more cover to this site. The off-site disposal rule (40 CFR ~ 300.440) is
also relevalnt and appropriate to the selected remedy. Any hazardous substance, pollutant, or
contaminant identified during the implementation of the selected remedy will be disposed of in
accordancl~ with this regulation. Action-specific ARARs for LF04 are identified in Table 3.5-1.
Table 3.5-1
Identification of Action-Specific ARARs, LF04 .
Elmendorf AFB, AK
Standard,
Requirement. Criteria, or Citation Description Documentation
Limitation
National Oil and Hazardous 40 CFR Establishes procedures for planning Relevant and appropriate if
Substances. Pollution ~ 300.440 and implementing off-site transfer hazardous substances,
Contingency Plan--Off-Site of any hazardous substance, pollutants or contaminants are
Disposal Rule pollutant, or contaminant. transferred off site during
implementation of the selected
remedy.
State of Allaska
Alaska Solid Waste 18 AAC Provides requirements for closure Requirements are relevant and
Management Regulations 60.390 . of solid waste municipal landfills. appropriate to the landfill at
LF04.
AAC
CFR
. Alaska Administrative Code
- Code of Federal Regulations
Cost Effectiveness
The remedy is the most cost effective of the alternatives because it affords overall
effectivene:ss proportional to its costs. The no action alternative has no costs, but it does not meet the
RAOs.
Utilization of Permanent Solutions and Alternative :Treatment Technologies to the
Maximum Extent Practicable
The USAF and the USEPA have determined that the selected remedy represents the
maximum extent to which permanent solutions and treatment technologies can be used in a cost-effective
manner at LF04. The State of Alaska concurs. with these detenninations.
Preference for Treatment as a Principal Element
The COC for the LF04 NorthlBeach soils is exposed landfill waste. Treatment cannot be
used to reduce this material; therefore, it will be removed from the site.
3.5.2
Documentation of Significant Changes
The Proposed Plan listed soil and groundwater contaminants with concentrations in
excess of cleanup goals (ACM guidelines and MCLs). This list was different from the COCs established
in Section 3.3.3, because identification ofCOCs included evaluation of risk along with comparison to
cleanup levels. This change was a logical outgrowth of the Proposed Plan and did not affect the choice
January 1997
3-31
OU 6 ROD, Final
-------
of alternatives at LF04. Thus, the selected remedy was the preferred alternative presented in the
Proposed Plan (Table 7 of the Proposed Plan).
OU 6 ROD, Final
3-32
January 1997
-------
SECTION FOUR
-------
4.0
4.1-1
4.1-2
4.2-1
4.3-1
4.3-2
4.5-1
TABLE OF CONTENTS
Page
S()URCE SD 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 4-1
4.1
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1.1 Land Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1.2 Hydrogeology and Groundwater Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Site History and Enforcement Activities' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.2.1 Identification of Activities Leading to the Current Contamination
at SD 15 [[[ . 4-3
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . . 4-5
4.3.1 Nature and Extent of Contamination ...............................4-5
4.3.2 Risk Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15
4.3.3 Conclusions. . . . . . . . . .'. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
Remedial Action Objectives, Alternatives, and Comparative Analysis
for SD 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18
4.4.1 Remedial Action Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18
4.4.2 Groundwater Alternatives. . .'. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23
4.4.3 Summary of Comparative Analysis of Groundwater Alternatives. . . . . . . . . 4-23
4.4.4 Soil Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23
4.4.5 Summary of Comparative Analysis of Soil Alternatives. . . . . . . . . . . . . . . . 4-26
Selected Remedy for SD 15 ............................................. 4-29
4.5.1 Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-33
4.5.2 Documentation of Significant Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-36
4.2
4.3
4.4
4.5
LIST OF FIGURES
Page
LClcation Map for Source Area SD 15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Conceptual Hydrogeologic Model for SD 15 """"""""""""""""""" 4-4
Contaminant Release Mechanisms and Potential Pathways for Exposure
at SD 15 [[[ 4-6
Fuel and Chlorinated Solvent Plume in the Groundwater at SD 1 5 """""""""'" 4-21
-------
4.3-1
4.3-2
4.3-3
4.3-4
4.3-5
4.3-6
4.4-1
4.4-2
4.5-1
4.5-2
LIST OF TABLES
Page
Summary of Groundwater Analytical Results for the Shallow Perched Aquifer
at Source SDIS, Elmendorf AFB, AK ...........................................4-7
Summary of Groundwater Analytical Results for the Deep Aquifer
at Source SOlS, Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
Summary of Surface Soil Analytical Results for Source SO 15,
Elmendorf AFB, AK [[[ 4-10
Summary of Subsurface Soil Analytical Results for Source SOlS,
Elmendorf AFB, AK [[[ 4-12
Summary of Human Health Risks at SO 15, Elmendorf AFB, Alaska. . . . . . . . . . . . . . . . . . . 4-16
Summary of Contaminants of Concern at SO I S, Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . 4-19
Cost and Time to Cleanup for Groundwater Alternatives at SO IS,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-24
Cost and Time to Cleanup for Soil Alternatives at SOlS,
. Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24
Identification of Chemical-Specific ARARs and Remediation Goals, SO 15,
-------
Section 4.0
SOURCE SD15
The following subsections describe the physical description, land use, groundwater use,
and hydrogeology of SD 15. The identification of activities which led to the current contam ination at
SD 15 is also included. The discussion of the regulatory and enforcement history of SD 15, the role of the
response action at SD 15, and community participation in the response action are included in the general
au 6 discussion in Section 1.0.
4.1
Site Description
Source SD ISis the third of the au 6 source areas located on the Elmendorf Moraine.
This sourc:e area is located several thousand feet to the east of Sources LF04 and WPI4 at an elevation of
approximately 275 feet above mean sea level. This source, which is located off Hubble Road, consists of
four separate 30- by 50-foot concrete pads (Figure 4.1-1). The pads were used from the early 1970s to
1983 for weathering fuel filters and pads, and for the disposal of tank sludge. Strong fuel odors, fuel
stains on the soil, and fuel filters and pads have been noted at the source area around three of the
concrete pads (Pad Nos. I, 2, and 3). Cracks were also observed in the weathering pads.
During a walk-through survey ofthis source area conducted in the summer of 1993, a
total of 17 old building foundations or concrete pads were noted in the general vicinity. The road was
originally cleared to four of these pads to prepare them to be used for weathering and sludge disposal
activities. However, available historical information indicates that disposal activities took place at only
the first three pads (Pads Nos. 1,2, and 3). All four pads were investigated during the LFI (USAF,
1993). Based on the results of the LFI sampling effort, and the historical evidence, only the first three
pads required further investigation as part of au 6 (Concrete Pad Nos. 1, 2, and 3 in Figure .4.1-1).
4.1.1
Land Use
The land use designation for SD ISis open space in the Base Comprehensive Plan. There
are no known historic buildings, archeological sites, wetlands, floodplains, or rare or endangered species
at SDI5.
4.1.2
Hydrogeology and Groundwater Use
The subsurface geology at Source SD IS is relatively complex, as would be expected in
glacial moraine deposits. The predominant lithologies encountered include silty sands, sandy and silty
gravels, and, to a lesser extent, sandy or gravelly clays. These lithologies are interfingered both
horizontally and vertically. Groundwater flow is mainly within these relatively permeable sand and
gravel zones and silty sand layers, which are believed to be laterally continuous or, at a minimum,
laterally communicating. .
Two different aquifer systems were identified at Source SD15 during the 1994 RI: a
perched groundwater system, and a deeper unconfined aquifer system. The perched groundwater system
was encountered in a relatively localized area at relatively shallow depths (20-45 feet bgs) at Source
SDI5. The areal extent of the perched zone is depicted in Figure 4.3-1, in Section 4.3, and is based on
water level information from both monitoring wells and soil borings drilled during the 1994 RI.
The presence of the perched groundwater zone is probably the result of low permeability
deposits which allow for groundwater accumulation to take place. Water levels in monitoring wells
completed in the perched groundwater zone were noted to decrease continuously during the summer,
January 1997
4-1
OU.p ROD, Final
-------
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Figure 4.1-1. Locaa...Map for Source Area SDIS
-------
with one well (MW-28) drying up completely. This could indicate that the perched aquifer is seasonal in
nature, and therefore has a variable geometry.
In addition to the shallow wells installed, deeper monitoring wells were also installed at
a depth of approximately 115 feet bgs in a regional unconfined aquifer. This deep unconfined aquifer
consists of well-graded, sandy gravel. The Bootlegger Cove Fonnation was not encountered in any of
these thre~: deep monitoring wells. This deeper of the two aquifers is believed to correlate with the
unconfined shallow aquifer underlying the outwash plain (OUs 3 and 4). Vertical migration between the
perched and deeper aquifers at S015 is possible. However, chemical and modeling results obtained
during the RI indicate that downward contaminant migration appears to be insignificant as a result ofthe
vertical di:;tance and the presence of fine grained deposits between the two aquifers.
Groundwater contours generated for the deeper aquifer indicate an almost flat water
surface, with a small east-northeast hydraulic gradient of about 10 feet per mile. Groundwater flow in the
shallow perched aquifer appears to trend toward the northwest, with a relatively steep hydraulic gradient
of approximately 700 feet per mile. While perched aquifers typically tend to have a mound shaped
potentiomc:tric surface, a substantial recharge feature, namely a marshy area, was identified upgradient
and partially overlying the perched aquifer at S015. The presence of this recharge area could account
for the rela.tively steep gradient documented within the perched aquifer.
A range in hydraulic conductivity for the shallow aquifer was calculated from slug tests
at 2.88E-4 to 4.5 I E-5 em/sec. For the deep unconfined aquifer, slug test results indicate high
conductivi:ties based on the virtually instantaneous water level recovery in the wells. The range in
conductivilty values obtained, 1.0E-l to I.OE-3 em/see, is typical of unconsolidated glacial deposits. A
generalized hydrogeologic conceptual model for this area is presented as Figure 4. 1-2.
The groundwater in the shallow aquifer, which is believed to correspond with the deeper
of the two aquifers encountered at SO 15, is not used for any purpose on base. Its future use is generally
limited bec:ause of the higher yield of the deeper confined aquifer below the Bootlegger Cove Clay. At
SO 15, the fine-grained nature of the perched aquifer material, coupled with the laterally discontinuous
nature of the perched aquifer, would make this aquifer wholly unsuitable as a drinking water supply
aquifer.
4.2
Site History and Enforcement Activities
The following section identifies the activities which lead to the current contamination at
SO 15. Th<: regulatory and enforcement history for SO 15 is included in the general discussion presented
for OU 6 in Section 1.0, as are the discussions of the role of the response action and the community
participation in the response.
4.2.1
Identification of Activities Leading to tbe Current Contamination at SD15
Groundwater and soil contamination at SDI 5 consists primarily of metals, HVOCs, and
fuel-related constituents. The source of contamination at SO ISis directly related to the waste
management practices conducted in this vicinity. The primary sources for POL contamination at this site
are identified as the vari<;)Us spent petroleum products and solvents which were either stored in
abovegroull1d tanks, contained in filter elements, or otherwise released onto the cement pad or open
ground at Source SO I S. Weathering of fuel filters, pads, and tank sludge made both metals and fuels
available ti)r leaching into the soil and groundwater. Minimal contamination has reached the deeper
aquifer at SO 15. Another possible source of contamination at Source SO 15 was identified as product
loss during removal of contaminated items from the transport vehicles.
January 1997
4-3
OU 6 ROD, Final
-------
~
I
~
....
~
c
~
-
'-D
'-D
-...I
//
/
Source SD15
/
"
/
----.
Perched Aquife~ (sand and silt)
TYPically 10-20 feet thick and
30-40 feet below ground Surface.
Localized Confining cloy unit.
Exact thickness unknown.
10
"!
"!
....
d P ched Aquifer
Legen Flow- er
of Groundwater
- .. Direction
....
....
'"
o
"
Figure 4.1-2.
d I fior SDtS
. Mo e
I Hn!rogeologlc
Conceptua
-------
Soil contamination at SOlS also represents a continuing source for future groundwater
contaminaltion via percolation of water through the vadose zone. Oownward vertical migration of
groundwater from the contaminated upper perched aquifer at SO 15 also acts as a contaminant source for
the deeper aquifer. Seasonal fluctuations in the water table have also resulted in a smear zone being
detected at the base of the vadose zone above the perched aquifer at SOlS. A schematic of the potential
migration and exposure pathways of fuels and solvents through the soil and into the groundwater is
presented in Figure 4.2-1.
Prior to the Rl conducted at SO 15 in 1994, SO 15 had been addressed under the
following studies:
.
IRP Phase I/II Records Search and Statement of Work (Engineering-Science, 1983);
.
IRP Phase II Stage 3 Work Plan (Harding Lawson, 1988);
.
RCRA Facility Assessment Report (AOEC, 1988);
.
IRP Phase III, Stages 3 and 4, Remedial InvestigationlFeasibility Study (Black and
Veatch, 1990); and
.
OU 7 Limited Field Investigation Work Plan ( USAF 1993b), and Limited Field
Investigation Report (USAF, 1993a). .
The use of SO 15 facilities for the weathering of fuel filters and pads was discontinued in
1983. Weathered fuel filters and two above ground storage tanks in the vicinity ofSD15 which could
have also a.:ted as potential contaminant sources were removed and disposed of in the summer of 1996.
4.3
Site Contamination. Risks. and Areas Requiring Response Actions
This section identifies the areas which were investigated, and those that require remedial
action. Th(:se areas were chosen based on the risk that contaminants pose to human health and the
environment. The basis of this analysis is the data collected during the Remedial Investigation (RI)
which identified the nature and extent of contamination at SO 15.
Nature and Extent of Contamination
Ouring the RI, samples of soil and groundwater were collected and analyzed for organic
and inorganic constituents. Significant levels of contaminants were detected in both the soil and
groundwat(:r at SD 15. These contaminants include fuels and fuel constituents, solvents, metals, and
SVOCs. The contamination present at S015 is associated with contaminant transport in the vadose zone,
dissolved a,queous transport, and volatilization. These transport mechanisms are pictorially represented
for SOlS in Figure 4.2-1.
4.3.1
Tables 4.3-1 through 4.3-4 list the frequency of occurrence and maximum concentrations
of all constituents which were detected during the RI in groundwater and soil. The tables do not include
results below the detection limit. The MCLs for groundwater and the ACM guidelines for soil are also
listed on th,~ tables for all constituents. Results are separated between "indicator parameters" and
"contaminant parameters." Indicator parameters primarily include metals classified as nutrients, and
non-speciated fuel constituents such as UORO which are unsuitable for use in a risk assessment. A
detailed discussion of the determination of the COCs for SOlS is presented in Section 4.3.3.
January 1997
4-5
OU 6 ROD, Final
-------
. VOfofilirolion of -,. ~ Fug//l.. Du$/
VOp()f' Phon "- G.n.rofion
1~~,' ,;".,,':',,:::. '~ )l-!~'\:5;;~
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Zone
Seasonal High
Water Table
SeaSonal L
ow Water Table
Dissolved Phose Contamination
-
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-.I
LNAPLS
Low probability for groundwater contaminofion by organics is believed to exist at this source area based on the significant
depth to groundwater (>84 feet). and vadose zone transport modeling results for organic constituents (Appendix r).
Additional site-specific informatIon regarding soil-water partition characleristics of inorganics is necessary in arder
to assess the potential for migration of these species to groundwater. The potential for exposure to theroretically
contaminated groundwater is also believed to be low because of the expectation of insufficient yield in the moraine
deposits to support a residential well in this area.
'"
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Figure 4.2-1. Contaminant Release MecbaJ1isms and Potential Pathways for Exposure at SDIS
-------
Table 4.3-1
Summ~lry of Groundwater Analytical Results for the Shallow Perched Aquifer at Source SDIS
. Elmendorf AFB, AK
Frequency of Location of
:\Iethod Analyte MCL' Maximum Detections
(uDib) Result Total Hits! Mnimum
Total Samples Ruulr
Indicator F'arameters
SW8015ME (",gIL) Unidentified organics (UDROJ -- 8490 E 2/4 MW-18
SW8015MP (",gIL) Unidentified organics (UGROJ - 24000 b 1/4 MW-18
Xylene (total) 10000 3940 4/4 MW-18
SW6010, Total (mgIL) Aluminum -- 1.05 4/4 MW-17
Calcium -- 151 4/4 MW-17
Iron - 10.2 4/4 MW-17
Magnesium - 32.2 4/4 MW-17
Potassium -- 2.09 3/4 MW-17
Sodium -- 6.25 4/4 MW-18
SW6010, Dissolved (mg/L) Calcium -- 153 3/3 MW-17
Iron -- 8.11 3/3 MW-18
Magnesium - 33.3 3/3 MW-17
Potassium - 2.42 3/3 MW-17
Sodium - 6.33 3/3 MW-18
Contaminant Paramders
SW8015ME (",gIL) Jet fuel (JP-4) - 8620 2/4 MW-18
SW8015MP' (",g/L) Gasoline - 31700 3/4 MW-18
SW8260 ("'I~) Acetone - 129 4/4 MW-17
Benzene 5 1430 4/4 MW-18
2-Butanone(MEK) -. 17.7 4/4 MW-18
Chloroethane - 0.2 1/4 MW-18
Chloroform 100 6.28 4/4 MW-18
Chloromethane -- 4.33 4/4 MW-17
I,I-Dichloroethane -- 185 3/4 MW-18
I,I-Dichloroethene - 2.11 4/4 MW-18
1,2-Dichloroethane 5 5.92 3/4: MW-18
cis-I,2-Dichloroethene 70 32.5 4/4 MW-17
trans-I.2-Dichloroethene 100 0.91 4/4 MW-17
Ethylbenzene 700 713 4/4 MW-18
2-Hexanone u 14.4 2/4 MW-18
Methylene chloride 5 2.72 B 4/4 MW-18
4-Methyl-2 -pentanone(MI BK) -- 28.2 4/4 MW-18
1.1.2.2- Tetrachloroethane -- 8.6 4/4 MW-18
Tetrachloroethene 5 0.53 3/4 MW-18
Toluene 1000 3640 4/4 MW-18
1.1.1- Trichloroethane 200 26.2 2/4 MW-18
1.1.2- Trichloroethane 5 6.97 1/4 MW-18
Trichloroethene 5 143 4/4 MW-18
Vinyl chloride 2 0.31 2/4 MW-18
m & p-Xylem: -. 2510 4/4 MW-18
o-Xylene -- 1460 4/4 MW-18
January 1997
4-7
au 6 ROD, Final
-------
Table 4.3-1
(Continued)
Frequency of Location of
~Iethod Analyte MCL' Mulmum Detections Muimum
(uaits) Result ToClI Hits!
ToClI Samples Result
SW6010. Total (mgll) Barium 2 0.0672 4/4 MW-17
Bery Ilium 0.004 0.00127 B 3/4 MW-18
Cadmium 0.005 0.00414 B 1/4 MW-18
Chromium 0.1 0.0541 2/4 MW-17
Cobalt - 0.0238 2/4 MW-18
Manganese - 14.5 4/4 MW-17
Nickel 0.1 0.0558 214 MW-17
Zinc - 0.0931 4/4 MW-18
SW7060, Total (mgll) Arsenic 0.05 0.065 4/4 MW-17
SW7421, Total (mgll) Lead 0.015 } 0.00231 1/4 MW-17
SW6010, Dissolved (mg/L) Barium 2 0.0604 3/3 MW-17
Beryllium 0.004 0.0127 B 3/3 MW-17
Cobalt - 0.0711 213 MW-17
Manganese - 15.5 3/3 MW-17
Nickel 0.1 0.0201 2/3 MW-18
Zinc -- 0.035 3/3 MW-17
SW7060, Dissolved (mg/L) Arsenic 0.05 0.0606 3/3 MW-17
I Maximum contaminant level (MCL); 40 CFR ~ 141.61 for Federal MCLs, and 18 AAC 80.070 for State MCLs. Federal and State
MCLs are idenlical for the listed constilUenlS.
1 Frequency .hits. calculation does not include one or more results removed from the data set because they did not meet QAlQC criteria.
TOIaI sample count includes all samples analyzed for the indicated parameter.
, From 40 CFR. Section 141.11 for inorganics and Section 141.12 for organics (effective I July 1991); however. the lead level is effective
only until 7 December 1992. There is no longer an MCL for Ie:ad or copper (56 Federal Re:e.iste:r 26460, June: 7. 1991); however. there is
an action level of 0.0 I 5 mg/L for Ie:ad and 1.3 mgll for copper.
B - Sample concentration was less than or equal to the blank UTL.
E - Analyte concentrations exceeded calibration range.
F - Interference or co-elution suspected.
OU 6 ROD, Final
4-8
January 1997
-------
Table 4.3-2
Sllimmary of Groundwater Analytical Results for tbe Deep Aquifer at Source SDtS
Elmendorf AFB, AK .
Frequency of LOtalion of
Method Maximum Deteclion
(~Inits) Analyte MCL1 Result Total Hibf Maximum
Total Samples Results
Indiutor Parameters
SW8015ME (ligIL) Unidentified organics (UDRO] - 31.5 B 6/6 MW.7IA
SW80 I 5MP (ligIL) Unidentified organics (UGRO] - 40.5 B 4/6 MW-72
Xylene (total) 10000 1.03 6/6 MW-70
SW6010. lrotal (mgIL) Aluminum - 0.228 5/6 MW-70
Calcium - 54.2 6/6 MW-72
Iron .. 0.403 6/6 MW-7IA
Magnesium .. 7.28 6/6 MW-70
Sodium - 2.55 6/6 MW-70
Contaminant Parameters
SW8260 (1IgIL) Acetone -- 1\.3 B 6/6 MW.7IA
Carbon tetrachloride 5 0.58 6/6 MW-7IA
Chloroform 100 0.13 B 1/6 MW-7IA
Chloromethane - 2.09 B 6/6 MW-72
1.2-Dichloroethane 5 2.07 B 5/61 MW-7IA
Ethylbenzene 700 0.29 5/6 MW-70
Methylene chloride 5 2.26 B 5/6 MW-7IA
Toluene 1000 0.67 6/6 MW-70
Trichloroethene 5 0.67 2/6 MW-72
m & p-Xylene - 0.62 3/6 MW-70
o-Xylene -- 0.22 B 3/6 MW-70
SW6010. Total (mgIL) Barium 2 0.011 6/6 MW-72
Beryllium 0.004 0.00128 B 3/6 MW-70
Chromium 0.1 0.00525 1/6 MW-70
Manganese -- 0.0639 6/6 MW-7IA
Zinc - 0.0136 B 5/6 MW-72
SW7421. Total (mgIL) Lead 0.015) 0.00386 1/6 MW-70
I Maximum conraminant level (MCL); 40 CFR ~ 141.61 for Federal MCLs, and 18 AAC 80.070 for Srate MCLs. Federal and Srate
MCLs am idenrical for the lisled conslilUents.
1 Frequenc.y 'hits' calculation does not include one or more results removed from the dara set because they did nol meet QA/QC crileria.
Toral sample count includes all samples analyzed for the indicated parameter.
, From 40 CFR. Section 141.11 for inorganics and Section 141.12 for organics (effective I July 1991); however, the lead level is effective
only until 7 December 1992. There is no longer an MCL for lead or copper (56 Federal Rel!ister 26460. June 7. 1991); however, there is
an action level of 0.015 mgIL for lead and 1.3 mgIL for copper.
B - ~;arnple concentration was less than or equal to the blank UTL.
January 1 '~97
4-9
OU 6 ROD, Final
-------
Table 4.3-3
Summary of Surface Soil ADayltical Results for Source SDlS
ElmeDdorf AFB, AK
BackgrouDd FrequeDC:Y of Location of
Metbod Aualyte ACM Upper MaDmum Detection MaDmum
(units) Tolenuce Result total bil3l
Umit total samDles Ruult
IDdicator Paramden
SW9045 (DH units) DH - - 6.22 2fJ. SS-072
D2216 (oercen!) Percent moisture - - 48.2 36/36 SS-078
AX. DRO (m2lkR) Diesel RanRe DrRanics 2000 - 10000 4n E7-SS-03
AX. GRO (mllllul) Gasoline Ranlle Onranics 1000 - 33000 3/8 E7.SS-03
SW8015ME (m2lkR) Unidentified orRanic:s rUDROl 2000 - 7210 26129 SS-075
SW8015MP(m2lkR) Unidentified OrRIDic:s rUGROl 1000 - 11500 15/29 SB-19
SW60IO (mglkg) Aluminum - 31183.96 26500 36/36 SS-072
Calcium - 8013.23 31200 36/36 SB.19
Iron - 43192.35 28900 36/36 SS-078
Ma~esium - 10904.10 8390 36/36 MW-18
Potassium - 845.75 926 36/36 E7-SB-05
Sodium - 427.05 1410 36/36 SB-23
CODtamiDa.t Panmden
S W80 10 (jlglkg) Chloromethane - - 28.5 B 1/8 E7-SB-04
Melhvlene chloride - - 76 B 6/8 E7-SS-05
1.1,2.2 - T ettac:hloroelhane - - 97900 1/8 E7-SB-06
1,1.1- Trichloroelhane - - 9260 1/8 E7-5S-03
T richloroelhene - - 1200P 2/8 E7-SB-06
SW8015ME (mglkg) Diesel 2000 - 252 2fJ.9 SB-24
Kerosene 2000 - 4210 1129 SB-19
SW801 5MP (;lglkg) Benzene 500 - 5.24 B 1129 55-77
Ethvlbenzene 10000 - 24600 4129 SB-19
Toluene 10000 - 2370 5/29 SS-75
Xvlene (total) 10000 - 141000 11/29 SB-19
SW8020 (jlglkg) Benzene 500 - 37.9 1/8 E7-5S-05
Chlorobenzene - - 22000 P 4/8 E7-SS-03
1.2-Dichlorobenzene - - 307000 418 E7-SS-03
1,3-Dichlorobenzene - - 165000 4/8 E7-SS-03
1.4-Dic:hlorobenzene - - 147000 3/8 E7-SS-03
Elhvlbenzene 10000 - 51400 4/8 E7-SS-03
Toluene 10000 - 34000 6/8 E7-SS-03
X vlene (Iota\) 10000 - 594000 7/8 E7 -SS-03
SW8240 (J.'gIkg) Acetone - - 224 19129 SS-078
2-Bulanone (MEK) - - 8.21 B 11129 SS-078
Chloroform - - 20 1129 MW-17
1,1- Oichloroelhene - - 10.3 2fJ.9 SS-075
Melhvlene chloride - - 12.5 26129 S8-19
1,1,2,2- Tetrachloroethane - - 11.5 1129 MW-17
Tetrachloroethene - - 48.2 3/29 SB-19
au 6 ROD. Final
4-10
January 1997
-------
Table 4.3-3
(Continued)
Blck&rouDd FnqaeDcy of LourioD of
Mert,od Upper Mllimum DetfttioD
(uuillS) Aallyte ACM ToleraDce Result 10UlI bits! Muimum
Limit tOUlI Slmnles Result
SW8240 (J,lll>'kg) 1.1. 1- T rich loroethane - - 66.7 1/29 SS-075
(conlinued) Trichloroethene - - 279 2/29 SB.19
m & p..Xvlene - - 122000 1/29 SB-19
<>-Xvlene - - 55100 1/29 SB.19
SW8270 (miYkg) Benzo( a )anthracene - - 0.0226 In E7-SB-04
Benzo( a )DYmle - - 0.0274 In E7-SB-04
Benzo(b )f\uoranthene - - 0.056 F In E7-SB-04
Benzo( ILh i)nervlenc - - 0.0274 In E7-SB-04
Benzolk)f\uoranthene - - 0.056 F In E7-SB-04
bis(2- Ethvlhexvl)Dhthalale - - 2.23 6n E7-SS-04
DibenZ{ a.h )anthracene - - 0.0105 J In E7-SB-05
Fluoranthene - - 0.0244 In E7-SB-04
Indenol 1.2.3
-------
'.~~~~
Table 4.3-4
Summary of Subsurface Soil Analytical Results for Source SDIS
. Elmendorf AFB, AK
Background . Depth of Frequency of Location of
Method ACM' Upper Maximum Detection
(unib) Aaalyte Guideline Tolenau Rault Muimum Total Hital Mllimum
Limit Result (R.) Total SamDla Result
Indicator Parameters
SW904S (pH units) pH - .. 7.94 36 III S8-21
D2216 (percent) Percent moisture - .. 22.9 j6 95195 MW-18
AK DRO (mglkg) Diesel Range Organics 2000 - 6000 9 6/15 E7-S8-03
AK GRO (mglkg) Gasoline Range Organics 1000 - 21000 4.5 6/15 E7-SB.OI
SW8015ME (mglkg) Unidentified organics 2000 - 17.8 35.75 29/31 MW-18
[UDRO)
SW8015MP (mg/kg) Unidentified organics 1000 _0 1490 4 21/33 SB-24
[UGRO)
SW60IO (mglkg) Aluminum - 18116.77 18600 4 47/47 E7-SB-06
Calcium - 10264.39 18400 SO 47/47 SB-2S
Iron - 38483.64 96400 25 47/47 E7-SB-03
Magnesium - 14784.34 9820 36 47/47 SB-19
Potassium - 1114.35 1330 30.5 47/47 MW-18
Sodium - 365.59 249 30.5 47/47 MW-18
Contamiaaat Parameters
SW8010 ~glkg) cis-I,2-Dichloroethene - - 105 36 1115 E7 -SB-O 1
I,I-Dichloroethane - - 881 4.5 2/15 E7-SB-OI
Methylene chloride -- - 174 B 44 9/15 E7-SB-02
1,1,2.2- Tetrachloroethane - - 918 21 4/15 E7-SB-06
Tetrachloroethene - - 66.6 16 2/15 E7-SB-04
1.1,1- Trichloroethane - - 7740 4.5 3/lS E7-SB-OI
Trichloroethene - - 1740 21 11/15 E7-SB-06
SW8015ME (mglkg) Diesel 2000 - 29.4 II 1/31 5B-24
Kerosene 2000 .. 19.9 16 1/31 S8-19
SWBOl5MP ~glkg) Benzene 5001 .. 420 28 9/33 MW-17
Gasoline 1000000 -- 11700 46 1/33 MW-18
Ethylbenzene _1 .. 1540 36 7/33 5B-23
Tolune _1 .. 1780 36 10/33 SB-23
Xylene (total) ..1 - 10700 4 10/33 SB-24
SWB020 ~glkg) Benzene 500 1 - 11900 4.5 6/15 E7-SB-OI
Chlorobenzene - - 11400 P 4.5 4/15 E7-SB-01
1.2-Dichlorobenzene - - 18500 P 4.5 7/15 E7-SB-OI
1.3-Dichlorobenzene - .. 5110 9 2/15 E7-SB-05
1,4-Dichlorobenzene -- - 15500 P 4.5 3/15 E7-SB-OI
Ethylbenzene _1 - 62000 4.5 9/15 E7-SB.OI
Toluene _1 - 135000 4.5 10115 E7-SB.OI
Xvlene !total) _1 - 138000 20 lOllS E7-SB-03
OU 6 ROD, Final
4-12
January 1997
-------
Table 4.3-4
(Continued)
Background Depth of FrequeDcy of Location of
~iethod ADalyte ACM' Upper Maximum Maximum Detection Mnimum
(units) Guideline ToleraDee Result . Total Hits!
Limit Result (R.) Total Sam Dies Result
SW8240 (}lglkg) Acetone - - 40.18 28 26133 MW-17
2-Butanone (MEK) - -- 26.68 36 14133 MW.18
Chloroform -- - 153 28 4133 MW-17
I,I-Dichlorocthene -- - 26.4 36 4/33 MW-18
cis-I,2.Dichlorocthane - -- 26.7 36 4/33 SB-23
Methvlene chloride - -- 19.6 46 26133 SB-21
4-Methyl-2-pentanone -- .- 2.35 B 46 1/33 MW-18
(MIBK)
I, L2,2-Teuachloroethane - -- 8.24 36 1/33 MW.17
Trichlorocthene - - 181 36 8133 MW.17
m & p-Xylene _2 -- 1260 36 7/33 MW-18
o-Xylene _2 - 678 36 7/33 MW-18
SW8270 (mg/kg) Acenaphthene - - 0.0249 16 1/16 E7-SB-01
bis(2 -E thy Ihexyl )phthalate - -- 0.211 16 8/16 E7-SB-05
Butylbenzylphthalate - -- 0.403 9 1/16 E7-SB-05
Dibenzofuran -- - 0.0120 J 20 1/16 E7-SB-03
Fluorene - - 0.0197 20 2/16 E7-SB-03
2-Methylnaphthalene - -- 9.87 9 6/16 E7-SB-03
2-Methylphenol (o-cresol) - -- 0.0471 16 1/16 E7-SB-01
4-Methylphenol (p-cresol) -- -- 0.106 F 16 1/16 E7-SB-01
Naphthalene - -- 2.47 9 5/16 E7-SB-03
Phenol -- - 0.0448 21 1/16 E7-SB-01
SW6010 (mg/kg) Antimony -- NA 12.2 30.5 5/47 MW-18
Arsenic -- 9.31 12.1 6 9/47 E7-SB-04
Barium -- 95.93 661 9 47/47 E7-SB.03
Beryllium -- 0.64 0.341 25 47/47 E7-SB-03
Cadmium -- 3.07 1.3 25 9/47 E7-SB-03
Chromium - 76.94 46.2 26 47/47 S8-21
Cobalt - 17.62 16.5 25 47/47 E7 -SB-03
Copper -- 59.84 84.7 41 47/47 E7-SB-01
lead -. 10.13 56.2 16 47/47 E7-SB-05
Manganese -- 709.45 . 1770 46 47/47 SB-20
Molybdenum -- NA 2.39 25 47/47 E7-SB-03
Nickel - 71.79 48.4 36 47/47 SB-19
Selenium - 0.48 37.9 25 33/47 E7-SB-03
Silver - 1.06 0.638 6 1/47 E7-SB-04
Vanadium -- 66.16 64.2 30.5 47/47 MW-18
Zinc - 76.17 79.4 9 47/47 E7-SB.03
SW7060 (mglkg) Arsenic - 9.31 9.83 46 31/31 SB-19
SW7421 (mglkg) lead - 10.13 7.69 4 31/31 MW-18
I Alaska Cleanup Mauix (ACM) level D; 18 AAC 78.315.
, The ACM level D guideline for benzene, toluene, ethylbenzene, and xylenes (BTEX) combined is 100,000 jJg/kg.
B - Sample concentration was less than or equal to the blank UTL.
F - Co
-------
Groundwater Contamination at SD1S
Groundwater data at SOlS was characterized as two distinct aquifers based on the
hydrogeology. The groundwater data were separated into groundwater results from the perched aquifer
(Table 4.3-1) and groundwater results from the deeper aquifer (Table 4.3-2). The predominant type of
groundwater contamination detected at SO 15 includes fuel constituents, solvents and other VOCs, and
metals. The difference in levels of contamination between the perched aquifer and deeper aquifer at
SO 15 is substantial, with the deeper aquifer showing only minor levels of contaminants and fewer
contaminant species.
The perched aquifer results at SO 15 indicated elevated levels of BTEX and fuel
constituents, with a maximum benzene concentration of 1430 J.Lg/L in a sample from monitoring well
MW-18 (Table 4.3-1). This well had the highest levels of other fuel constituents as well, including
gasoline, jet fuel, UORO, UGRO, and other BTEX constituents. A recurring accumulation of several
inches of free phase floating product was also identified in this well. Solvent contamination is also
present at SOlS, with a maximum detection of 143 J.Lg/L for trichloroethene at MW-18. Other volatile
organic compounds were detected at substantially lower concentrations.
Numerous metals were also detected in the perched groundwater at SOlS. These include
relatively low concentrations of barium, beryllium, cadmium, chromium, cobalt, manganese, nickel, and
zinc (Table 4.3-1). As at other OU 6 source areas, a statistical comparison of these metals concentrations
was made to available background metals concentration from the Elmendorf Air Force Base, Alaska.
Basewide Background Sampling Report (USAF, 1993). Based on this evaluation, all metals evaluated in
both the aquifers at SO 15 were determined to be at or near background concentrations. The summary
statistics for the USGS data, including the upper confidence limit concentrations used for these
comparisons, are presented in Table 2.3-4.
Metals, VOCs, and fuels were detected in the groundwater collected from the deeper
aquifer at SO 15 (Table 4.3-2). All concentrations were significantly lower than those from the perched
aquifer, with most of the maxima from constituents being detected at or near the levels found in the
laboratory blank samples ("B" flagged), and the bulk of the remainder detected at concentrations below
1.0 J.Lg/L. Metals were also detected, but after the comparison to background metals, these were
determined to be at background concentrations.
Soil Contamination at SD15
Soil data from SO 15 were evaluated based upon surface and subsurface contaminant
occurrences. Surface soils include all soils collected from depths shallower than 3 feet bgs. Subsurface
soils are those collected from below 3 feet. Tables 4.3-3 and 4.3-4 list the sample depths, maximum
concentrations, locations, and guidelines associated with the ACM for non-UST soil for all contaminant
parameters in the surface and subsurface soil samples at SOI5. Results below the detection limits are not
included in the analytical summary tables.
The contaminants present in the surface soil at SOlS consist primarily of fuels,
weathered fuel residuals, solvents, and metals. Fuel components and metals were the most pervasive
contaminants. BTEX constituents were detected at a maximum of 594,000 J.Lg/kg in surface sample
E7-SS-03. Other fuels constituents, such as unidentified gasoline range organics (UGROs), were also
detected at substantially elevated concentrations. Benzene concentrations were lower in the surface soils
than in the subsurface soils; however, concentrations of solvents appear to be slightly higher. SVOCs
were only detected sporadically in the surface soils (Table 4.3-3).
OU 6 ROD, Final.
4-14
January 1997
-------
Contamination in the subsurface soils at SOlS were of generally similar types and
concentrations to those of the subsurface. Significant concentrations of BTEX (benzene at ] 1,900 J.lglkg,
toluene at 135,000 J.lglkg, ethyl benzene at 62,000 }.lglkg, and xylene at 138,000 J.lglkg) were detected in
the subsurface soils (Table 4.3-4). Other fuels constituents, such as UGRO, were also detected at
elevated kvels in (1490 mglkg). SVOCs and solvents were detected at significantly lower levels in the
subsurface: soils.
Metals were identified in both surface and subsurface soils at SOlS. The metals
detected were determined to be predominantly at or near background concentrations. The background
results used in the metals evaluation at SO 15 are included in the soil analytical tables (Tables 4.3-3 and
4.3-4). Analytical results from the basewide background sampling event (USAF, 1993) were pooled into
surface and subsurface soil results, and were used as the basis to conduct statistical comparisons with
on-site results.
4.3.2
Risk Evaluation
Based on the concentrations of contaminants detected during the RI, human health and
environmental risk assessments were performed to determine if areas should be considered for remedial
action. All concentrations of contaminants, including all contaminants of concern, whether exceeding
MCLs or ACM guidelines or not, were included in the risk assessments. The general discussion of the
human he2llth and ecological risk assessment procedures is presented in Section 2.3.2, and will not be
repeated since the procedures for each of the source areas within OU 6 were identical. Oetails on the
parameters used in the Health Risk Assessment are shown on Table 2.3-5.
Human Health Risk Assessment (lIRA)
Since SO 15 is not currently used residentially, a current residential risk scenario was not
evaluated, and only current visitor and trench worker scenarios were applied. Even though the future
land use at SO 15 is limited as specified in the Base Comprehensive Plan, the fUture residential risk
scenario was evaluated to obtain the most conservative risk information possible.
ELCRs and HIs were calculated to describe cancer and noncancer risks, respectively.
The ELCR. is the additional chance that an individual exposed to site contamination will develop cancer
during his/her lifetime. It is expressed as a probability such as I.OE-06 (one in a million). The HI
estimates the likelihood that exposure to the contamination will cause some negative health effect. An
HI score albove one indicates that some people exposed to the contamination may experience at least one
negative h'f:alth effect.
The calculated risks at SO 15 are based on hypothetical exposure to soil and
groundwater. Groundwater risk at SO 15 was calculated separately for the perched aquifer and the deeper
aquifer. The shallow groundwater aquifers at SO 15 are not presently used, and will not be used in the
future for supplying potable or non-potable water. For carcinogenic soil risk, the calculated results for
the future resident (RME), construction worker, and visitor are listed. Only the future resident scenario
(RME) was used to calculate carcinogenic groundwater risk. Table 4.3-5 summarizes the calculated
carcinogenic and noncarcinogenic human health risks calculated for SO 15.
Cancer risk using the residential RME scenario for the groundwater in the perched
aquifer at 5015 exceeds 1.0E-03. As at LF04 and WPI4, benzene is the predominant risk driver, with
several solivents contributing significantly as well. Noncarcinogenic risk for the perched aquifer is 25.1,
with toluene and ethyl benzene as the primary contributors. Carcinogenic risk in the deeper aquifer only
slightlyex.ceeds I.OE-06, due exclusively to carbon tetrachloride. Noncarcinogenic risk is below 1.0.
January 1997
4-15
OU 6 ROO, Final
-------
Table 4.3-5
Summary of Human Health Risks at SDIS
Elmendorf AFB, AK
Surface Soil (<3 feet) Subsurface Soil
Risk Chemical(s) Driving
Residential Visitor Trench Risk
. Scenario. Scenariob Worker Scenario'
Soil Risk d
Carcinogenic 1.6E-05 I.OE-06
-------
Shallow soil carcinogenic RME risk at SO 15 only slightly exceeded 1.0E-06 for both the
RME and visitor scenarios. Only the RME noncarcinogenic risk exceeded 1.0. No significant risk was
identified under the trench worker scenario. Soil risk was 100% attributable to metals, which are
believed to be at background concentrations.
Ecological Risk Assessment (ERA)
The ERA was performed to determine if the reported concentrations of chemicals or
calculated exposures to plants and wildlife at OU 6 are likely to produce adverse effects. Ecological
effects w(:re evaluated quantitatively by c~lculating Ecological Quotients (EQs). The ERA focused on
evaluating potential impacts of the contamination on selected indicator species: the moose, masked
shrew, m(:adow vole, black-capped chickadee, merlin, and peregrine falcon. The general discussion of
the ecological risk assessment procedures is presented in Section 2.3.2 and will not be repeated since the
procedure:s for each ofthe source areas within OU 6 were identical.
Calculated EQs exceeded 1.0 for the black capped chickadee, shrew and meadow vole at
SO 15 due to elevated levels of barium. The highest EQ equals 18000 and is associated with barium for
the black capped chickadee, followed by 4700 and 160, also for barium for the masked shrew and
meadow vole, respectively. The 95% UCL for the surface soil barium concentration is influenced by two
isolated high barium results obtained during the OU 7 LFI in 1993 (661 mglkg and 8420 mglkg). Such
high bari.lIm concentration were not observed in any of the samples collected during the 1994 RI. It
therefore appears that the high barium concentrations are associated with a localized anomaly and that
barium is not a significant contributor to ecological risk in the area. The EQ for the shrew was also
exceeded for selenium concentrations. Three organic constituents, benzo(a)anthracene,
bis(2-ethylhexyl)phthalate, and dibenz(a,h)anthracene also caused EQ exceedances for the black capped
chickadee: and the shrew. The highest organic EQ was 5.1 for benzo(a)anthracene in the black capped
chickadee:. EQs were calculated based on surface soil contaminant concentrations. None of the
calculated EQs exceeded 1.0 for the moose, peregrine falcon, or merlin at SOlS.
Uncertainties Associated with the Risk Assessment
The major assumptions and uncertainty factors for the OU 6 human health and
ecological risk assessments are presented in Section 2.3.2.
4.3.3
Conclusions
The following subsections provide a discussion of the determination of COCs for SO IS,
the location and extent of contamination by COCs in excess of preliminary cleanup goals, and a
summary statement about the risk to public health, welfare, or the environment if action is not taken at
SOlS.
Contaminants of Concern
Constituents exceeding preliminary remediation goals (MCLs for groundwater or ACM
guidelines for soil) were identified in the Proposed Plan. COCs were developed from the results of the
risk assessment and by considering preliminary remediation goals. Each constituent having an individual
contribution of greater than I.OE-06 carcinogenic (RME) risk, or an HI greater than 0.1 when the
. cumulative HI for the site is greater than 1.0, was considered as a COC. In addition, any constituent
exceeding preliminary remediation goals (MCLs for groundwater or ACM guidelines for soil) was also
considered as a COe. The final COCs for SO 15 are shown on Table 4.3-6, with the individual risk
contributed and basis for identifying the COC (risk or regulatory standard).
January 1997
4-17
OU 6 ROD, Final
-------
Seven COCs were identified for the perched groundwater at SOlS (Table 4.3-6). All of
the COCs contribute to excess risk. All of the constituents except I, I ,2,2-tetrachloroethane were also
identified as COCs due to the exceedance of MCLs. Thus, all COCs except 1,1,2,2-tetrachloroethane
were identified in the Proposed Plan as having exceeded regulatory guidelines. It is believed that most of
the perched aquifer at SO IS is contaminated, and that a groundwater plume of dissolved fuel and solvent
contamination is present over much of the site. The volatile organic plume at SOlS is depicted as Figure
4.3-1. This map is drawn based upon concentrations exceeding 5 J.lg/L, which is the MCL for benzene
and trichloroethene.. The estimate volume of contaminated groundwater is 97S,000 gallons.
One metal, arsenic, also exceeded MCLs. Arsenic was not identified as a COC because:
(I) the maximum concentration was detennined to be statistically below background levels; (2) the result
from only a single sample was only slightly over the MCL; and (3) arsenic was not identified as a risk
driver for groundwater.
The COCs identified for soil at SOlS are consistent with those contaminants listed in the
Proposed Plan as having exceeded regulatory guidelines. Three COCs were identified in the soils at
SOlS, including GRO, ORO, and BTEX. These constituents exceeded preliminary remediation goals at
multiple locations. These are graphically represented in Figure 4.3-2. Several areas of both shaJlow
(less than S feet bgs) and deep (greater than 5 feet bgs) soil contamination requiring cleanup are
identified in the figure. The estimated volume of contaminated soil is 650 cubic yards.
Metals were also detected in the soils at SOlS. These constituents were not identified as
COCs because: (I) their contribution to health risk was insignificant; (2) their concentration contributed
to health risk but was below potential cleanup levels; or (3) their concentration was comparable to
background levels.
Summary
Actual or threatened releases of hazardous substances from SO IS, if not addressed by
implementing the response action selected in this ROD, may present an imminent and substantial
endangennent to public health, welfare, or the environment.
Remedial Action Objectives. Alternatives. and Comparative Analysis for SD15
The following subsections discuss the remedial action objectives for SO IS, and present a
description of the various alternatives which were evaluated to achieve those remedial objectives. The
results of the detailed comparison made between those alternatives are also presented.
4.4
4.4.1
Remedial Action Objectives
Specific remediation alternatives were developed and evaluated for the areas with
potential risk, and that exceeded the preliminary remediation goals identified in Section 4.3.3. Specific
remedial action objectives for SO 15 are as follows: .
.
Prevent the domestic use (i.e., use resulting in ingestion and dennal contact of water, and
inhalation of vapors) of water in the perched aquifer having benzene; ethylbenzene;
toluene; I, I ,2,2-tetrachloroethane; I, I ,2-trichloroethane; 1,2-dichloroethane; and
trichloroethene in excess of MCLs and/or resulting in a cancer risk greater than I.OE-06,
or a Hazard Index greater than 1.0.
.
Prevent the possible migration of contaminants from soils having ORO, GRO, and
BTEX concentrations exceeding ACM Level O.
OU 6 ROO, Final
4-18
January 1997
-------
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Table 4.3-6
Summary of Contaminants of Concern I at SOtS
F.lmpnrinrf A FR. A J(
--------- -- - - -- -., . ---
.-
~
~
~
I
Chemical Maximum M8Iimum Cancer M8Iimum Hazard Basis for COC Remediation Basis for
Concentration Risk Index Goal Remediation Goal
Groundwater (Perched Aquifer):
Benzene 1430 IJg/L 2.5E-03 -- Exceeds MCL; contributes 5IJg/L MCL
to a risk> I.OE-06
Ethylbenzene 713 1Jg/L -- 2.7 Exceeds MCL; contributes. 700 1Jg/L MCL
to HI > 1
Tuluene 3640 1Jg/L -- 20 Exceeds MCL; contributes 1000 1Jg/L MCL
to HI > I
1,1,2,2- 8.60 1Jg/L 9.6E-05 .. Contributes to a risk> -- 2 ..
Tetrachloroethane I.OE-06
1.1,2- Trichloroethane 6.97 IJg/L 2.2E-05 <0.1 Exceeds MCL; contributes 5 j1g/L MCL
to a risk> I.OE-06
1,2-Dichloroethane 5.92 1Jg/L 3.0E-05 -- Exceeds MCL; contributes 5 j1 g/L MCL
to a risk> I.OE-06
Trichloroethene 143 1Jg/L 6.8E-05 2.0 Exceeds MCL; contributes 5j1g1L MCL
to a risk> I.OE-06;
contributes to HI > I
Shallow Soils (0-5 feet bgs):
GRO 33,000 mg/kg -- -. Exceeds ACM Level D 1000 mg/kg ACM Level 0
DRO 10,000 mg/kg .- -- Exceeds ACM Level 0 2000 mg/kg ACM Level 0
BTEX 168 mg/kg n .- Exceeds ACM Level 0 100 mg/kg ACM Level 0
\0
-------
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Table 4.3-6
(Continued)
Chemical Maximum Maximum Cancer Maximum Hazard Basis for cac Remediation Basis for
Concentration Risk Index Goal Remediation Goal
Deep Soils (>5 feet bgs):
GRO 5200 mglkg -- -- Exceeds ACM Level 0 1000 mglkg ACM Level 0
ORO 6000 mglkg -- -- Exceeds ACM Level 0 2000 mg/kg ACM Level 0
~
I
IV
o
Cancer risk :t I.OE-06 or HQ :t 0.1 for soil or groundwater scenario with a total HQ of:t 1.0; or concentrations found in excess of regulatory levels. Ifcancer risk or HQ did not exceed standards,
it was marked as "._". .
\,1,2,2- Tetrachloroethane does not have an MCl; therefore, there is no remediation goal. Cleanup will be considered complete when all other COCs meet MCls.
MCl - Maximum Contaminant level (40 CFR ~ 141.61 for Federal MCls; 18 AAC 80.070 for State MCls). Federal and State MCls are identical for the COCs.
ACM - Alaska Cleanup Matrix, Level D (18 AAC 78.31 S)
bgs . Below ground surface
BTEX - Benzene. toluene, ethyl benzene, and xylenes
COC - Contaminant of Concern
DRO - Diesel range organics
GRO - Gasoline range organics
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-------
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* Locotion where 1993
Contamination was Identified.
250
.
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.
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.
Surface Soil Sample Location
Monitor Well Location
Soil Boring Location
Surface Soil Contamination
(Less than 5 Feet)
Subsurface Soil Contamination
(Greater thon 5 Feet)
Surface and Subsurface Soil
Contamination .
Feet
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Figure 4.3-2. Areas o~ Contamination at 8015
-------
4.4.2
Groundwater Alternatives
As discussed in Section 4.3.3, the primary groundwater COCs for SOl S are HVOCs and
fuel constituents. Cleanup alternatives were developed separately for groundwater and soil; therefore,
the development of alternatives was segregated accordingly. The four most promising groundwater
alternatives ("G") were chosen on the basis ofthe nine CERCLA criteria. These included the following:
no action (G I); long-term monitoring with institutional controls and product recovery (G2); pump and
treat with institutional controls and long-tenn monitoring (G3); and high-vacuum extraction with
institutional controls and long-term monitoring (G4). Descriptions of the four groundwater alternatives,
.methods for detennining the time to complete cleanup, and an explanation of the cost estimations are
included in Section 2.4.2. The groundwater alternatives for SO I S are similar to those for WP 14ILF04
South, eX1:ept that air stripping would be not be included as part of Alternative G3. Also, extracted
groundwa,ter would be reinjected into the deep aquifer for Alternatives G3 and G4. Table 4.4-1
summarizes the cleanup times and cost estimates for the groundwater alternatives at SO 15.
4.4.3
Summary of Comparative Analysis of Groundwater Alternatives
The comparative analysis describes how each of the groundwater alternatives meet the
CERCLA evaluation criteria relative to each other. The groundwater alternatives for SO 15 are similar to
those for WPI4ILF04 South. 'Section 2:4.3 contains a comparative analysis of these alternatives. The
comparative analysis for SO 15 differs from that for WP 14ILF04 South in that the plume at SO I S is
contained in small perched aquifer; therefore, active treatment is more feasible from a technical
implementation and cost standpoint. WPI4ILF04 South has a wide spread plume in a non-homogeneous
aquifer and arduous and unstable togography (i.e., the bluff) that makes installation of an active
treatment system difficult and costly.
Another difference between WPI4ILF04 South and SOlS is in the length of time until
cleanup is complete. Table 4.4-1 shows the remediation times and,costs for SO] S. The time to cleanup
affects the: short-tenn effectiveness criterion. However, the order of preference for short-tenn
effectiveness for SO 15 would remain the same as for WP 14, because for both sites G4 has the shortest
remediation time followed by G2 and G3. The costs for SD I S also follow the same trend as for WP 14.
Cost--Alternative G I does not have any costs associated with it. The next least
expensive alternative is G2 ($328K), followed by G4 ($912K) and G3 ($1 ,280K). All costs are in
present value. .
State Acceptance-The State of Alaska has been involved in the development of the
. alternative:s for SO 15 and concurs with the USAF and the USEP A in the selection of Alternative G4,
high-vacuum extraction with institutional controls and long-term monitoring, for groundwater at SD 15.
The USAF will investigate and implement other remedial alternatives should the selected remedy prove
.to be unsuccessful at meeting the required cleanup levels.
Community Acceptance-All of the alternatives were presented to the public in the
Proposed !Plan. Based on the comments received during the public comment period, the public has no
preference: of alternatives.
4.4.4
Soil Alternatives
As discussed in Section 4.3.3, the primary cacs for SOlS are fuel constituents in the
soils. The five most promising soil alternatives (liS") were chosen on the basis of the nine CERCLA
criteria. These included the following: no action (S I); institutional controls with intrinsic remediation
January 1997
4-23
au 6 ROO, Final
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Table 4.4-1
Costs and Time to Cleanup for Groundwater Alternatives, SD1S
Elmendorf AFB, AK
Costs (Tbousands 01 $)
Alternative Time to Cleanup
Capital Annual O&M . Present Value" (years)
G2 1.71 34.7 328 12.7
G3 621 71.3 1280 12.7
G4 528 93.9 912 4.8
. O&M - Operation and maintenance
b Present value discount rate 5%
Table 4.4-2
Costs and Time to Cleanup for Soil Alternatives, SDlS
Elmendorf AFB, AK
Costs (fhouS8nds ofS) Time to Cleanup
Alternative Shallow Soils Time to Cleanup
C.pitlll O&M. Present Value II (years) Deep Soils (years)
S2 1.71 34.7 < 535 50 24
S3 157 22.3 < 470 0.25 24
S4 247 45.6 479 d 0.25 12
S5 292 46.6 524 < 0.25 12
. O&M - Operation and maintenance
b Present value discount rate = 5% .
< Annual cost for years that sampling is conducted. For Alternative S3. the O&M cost for those years that sampling is not
conducted is $3490. This includes the cost of maintaining the cap for 30 years, per CERCLA guidance.
d The cost of eKcavating and thermal treating surface soils (without bioventing) is about S42,000 with no O&M costs.
. The cost of eKcavating and compo sting surface soils (without bioventing) is about $87,000 with no O&M costs.
OU 6 ROD, Final
4-24
January 1997
-------
(ICIR) and long-term monitoring (52); capping with ICIR and long-term monitoring (53); excavation,
thermal treatment, and backfilling for shallow soils and bioventing for deep soils (S4); and excavation,
composting, and backfilling for shallow soils and bioventing for deep soils (S5).
Time to complete cleanup for intrinsic remediation (S2 and S3) and composting (S5)
was calculated using first order decay, with the most conservative published values of half-lives for the
primary contaminant of concern. The remediation time for bioventing was calculated using
biodegradation rates attained from bioventing treatability studies conducted at Elmendorf AFB. In both
cases, conservative degradation rates were assumed because hydrocarbon concentrations are low (i.e.,
low food source).
Except for the no action alternative, the cost of each alternative includes monitoring of
soil for thl~estimated time period to complete cleanup, up to a maximum of 30 years, in accordance
CERCLA guidance. Net present value cost was calculated using a 5% discount rate. Costs estimates
were calculated using the USAF RACER system and have an accuracy of -30 to +50 percent.
The alternatives are as follows:
Alternative SI: No Action
There are no costs associated with this alternative.
Evaluation of this alternative is required by CERCLA as a baseline reflecting current
conditions without any cleanup. This alternative is used for comparison with each of the other
alternative:s. It does not take into consideration future events such as intrinsic remediation; however,
intrinsic n:mediaton is expected to occur. As a result, cleanup levels are expected to be achieved within
the same time frame as the intrinsic remediation alternative (50 years for SOI5). This alternative does
not includ,~ long-term monitoring, controls, or access restrictions; therefore, potential exposure pathways
would not be eliminated and future degradation would not be monitored.
Alternative S2: Institutional Controls with Intrinsic Remediation and Long-term
Monitoring
Costs and time to cleanup for this alternative are presented in Table 4.4-2.
Soil would be remediated by natural processes (physical, chemical, and biological) that
reduce contaminant concentrations. Soil chemical properties at S015 are expected to eventually
attenuate the fuel contamination. Low temperatures and competition between contaminants could slow
biodegradation of organic contaminants. Contaminants at SO 15 should degrade to regulatory levels
within 50 years. While intrinsic remediation is working, existing land use restrictions would be used to ,
limit access to contaminated soil. Land use restrictions are part of the Base Comprehensive Plan. These
controls would prohibit construction of residences and prohibit excavation of soil in areas of soil
contamination that exceed acceptable levels. The USAF would monitor soil quality annually, until
cleanup levels are achieved. If there is any indication that intrinsic remediation is not achieving the
cleanup levels within the expected ,time frames, the remedial actions would be reevaluated and additional
action takcm if necessary.
Alternative S3: Capping for Shallow Soils and Institutional Controls, Intrinsic
Remediation, and Long-Term Monitoring for Deep Soils
Costs and time to cleanup for this alternative are presented in Table 4.4-2.
January 1997
4-25
OU 6 ROO, Final
.'"
-------
Alternative S3 includes installing a multi-layer cap over areas of shallow soil
contamination. These areas would be cleared and grubbed. Clean fill would be placed and compacted
over the areas of contamination to establish the necessary grade for drainage. The cap would include an
impervious layer (synthetic liner), a drainage layer (sand, drainage fabric, and filter fabric), and a
vegetative soil cover. The cap would effectively immobilize and therefore contain soil contaminants in
the unsaturated zone by reducing infiltration. Land use restrictions would be implemented to protect the
integrity of the cap. .
Capping would be ineffective for deep soils. Rainwater could infiltrate around the edges
of the cap. Also, the cap is not needed to prevent human dermal exposure or ecological exposure to deep
soils. Therefore, institutional controls and intrinsic remediation with long-term monitoring, as described
under Alternative S2 would be implemented for those areas with only deep soil contamination. The deep
soils have less contamination than the shallow soils; therefore, intrinsic remediation would take 24 years
for the deep soils.
Alternative S4: Excavation, Thermal Treatment, and Backfilling for Shallow Soils
and Bioventing for Deep Soils
Costs and time to cleanup for this alternative are presented in Table 4.4-2.
Alternative S4 includes excavating the contaminated shallow soils and transporting them
to a commercial recycling facility in the Anchorage area for treatment using low-temperature thermal
desorption. The excavated soils would be treated and returned to the site to backfill the excavation pits.
Confirmation samples would be collected to ensure that remediation is complete.
Alternative S4 also includes bioventing for the contaminated deep soils. In bioventing,
air is injected into the soils to increase the oxygen content. By in'creasing the oxygen content of the soil
gas, bioventing increases aerobic degradation of the contaminants by naturally occurring
microorganisms.
Alternative S5: Excavation. Composting. and Backfilling for Shallow Soils and
Bioventing for Deep Soils
Costs and tinie to cleanup for this alternative are presented in Table 4.4-2.
Alternative S5 includes excavating contaminated shallow soils, creating a compost pile
at the site, treating the soils until acceptable levels are reached, and backfilling the excavations with the
treated soils. An HDPE liner and soil pad would be constructed near the site of the excavation. Bulking
agents, nutrients, and water would be added to the contaminated soil to provide optimal conditions for
biological degradation of the fuel contaminants. In addition, the composted soil would be turned
regularly using heavy equipment. Soil from the pile would be sampled periodically to determine the
progress of the remediation. Alternative S5 also includes bioventing for the contaminated deep soils as
described under Alternative S4. Thus, Alternatives S4 and S5 differ from each other only as far as how
to remediate the shallow contaminated soil.
Summary of Comparative Analysis of Soil Alternatives
The comparative analysis describes how each of the soil alternatives meet the CERCLA
evaluation criteria relative to each other.
4.4.5
au 6 ROD, Final
4-26
January 1997
-------
Threshold Criteria
Threshold criteria are those that must be met for the alternative to be viable and relate
directly to the statutory findings discussed in Section 4.5.1. This category includes two criteria: overall
protectiolll of human health and the environment, and compliance with ARARs.
Overall Protection of Human Healtb and tbe Environment-Alternative S 1
(No Action) was the only alternative that failed to meet this criterion, because the RAO concerning
prevention of migration of contamination was not satisfied, and access by visitors to the site was not
restricted!.
Two alternatives partially met this criterion: Alternatives S2 and S3. These alternatives
protect human health and the environment, but it would require 50 years for S2 and 24 years for S3 to
meet ARARs during which time the migration of contaminan~ could occur. The potential for migration
is mitigate:d to a degree by soil capping in Alternative S3. Given the probable age of the contamination,
and the fa,:t that monitoring to detect contaminant migration would occur as part of both alternatives, the
incrementil increase in protectiveness offered by a cap would not likely offset the ecological impact
caused by capping, and the 'associated installation and maintenance costs.
As active treatments, Alternatives S4 and S5 provide the greatest protection to human
health and the environment. These alternatives fully meet this criterion since each contribute to the
reduction of contaminants through active treatment. The only difference between them is the treatment
technology for excavated shallow soils, which does not affect their protectiveness of human health and
the environment. After excavation and treatment of shallow soils, clean soil would be returned to the
excavatiollis. This would occur in less than one year, rather than the 50 years needed for shallow soils in
Alternativ4:s S2. Bioventing of deep soils would increase aerobic degradation and effectively reduce the
fuel contamination to acceptable levels in 12 years as opposed to the 24 years for deep soils with
Alternativ4~s S2 and S3. Environmental impacts caused by excavation could be mitigated through
revegetation.
Compliance with ARARs-Alternative S 1 is the only alternative which does not meet
this criterion. While intrinsic remediation is expected to occur, this process cannot be documented
without taking action via sampling. This alternative therefore cannot comply with ARARs.
Each of Alternatives S2, S3, S4, and S5 equally meet this criterion; since each provides
for the timely reduction of contaminants to levels below ARARs. For chemical-specific ARARs, the
only difference between the alternatives is the time it would take to reduce contaminant levels to below
ARARs. For Alternatives S2 and S3, ARARs would be met in approximately 50 and 24 years,
respectively. For Alternatives S4 and S5, ARARs would be met in approximately 12 years; therefore,
Alternativ<:s S4 and S5 comply more quickly with ARARs.
No location-specific ARARs have been identified for S015. Each alternative equally
meets the action-specific ARARs. The off-site disposal rule would have to be factored into the disposal
of excavat(~d soils.
Balancing Criteria
Balancing criteria are the primary basis for comparing alternatives. These criteria relate
the alternative to the site-specific conditions. The no action alternative (S I) is not evaluated based on the
balancing\:riteria or the modifying criteria, since it did not meet the threshold criteria. Balancing
January 1997
4-27
OU 6 ROD, Final
-------
criteria includes long-term effectiveness and permanence; reduction in toxicity, mobility, and volume
through treatment; short-term effectiveness; implementability; and cost.
Long-term Effectiveness and Permanence-This criterion has to do with long-term
protection of human health and the environment (reduction of risks), and adequacy and reliability of
controls. Long-term management ("controls") would include a 5-year review, land use restrictions, and
annual soil sampling. Of these four alternatives, 54 and 55 best meet this criterion, because these
alternatives require no long-term maintenance or monitoring following execution. 54 meets this
criterion somewhat more completely than 55, since the compost pile associated with shallow soil
treatment in alternative 55 may contribute to a somewhat greater degree of residual risk. Between
Alternatives 52 and 53, Alternative 52 meets this criterion slightly more completely than Alternative 53,
since minimal maintenance would be required on the soil cap. Institutional controls in place in
Alternative 52 would provide adequate and reliable controls for preventing exposure to shallow soil
con tam ination.
Reduction in Toxicity, Mobility, and Volume Through Treatment-Although
intrinsic remediation will reduce the toxicity and volume of contaminants, Alternatives 52 and 53 do not
meet this criterion, because intrinsic remediation and capping are not treatment alternatives. Alternatives
54 and 55 both fully meet this criterion, since both are active treatment alternatives which will
effectively reduce contaminant toxicity, mobility, and volume over time.
Short-term Effectiveness-This criterion evaluates risks to workers, the community,
and the environment during the period of time until remedial action objectives are met. Alternatives G2,
G3, and G4 each meet this criterion since each provides adequate protection and risk reduction while soil
contaminants are being reduced to acceptable levels. While risks posed to workers or the public would
be minimal for both alternatives during implementation, the time frame for achieving RAOs for
Alternatives 52 and 53 is substantially longer than for Alternatives 54 and 55. Community protection
would be imposed through institutional controls during implementation. 5ince capping mitigates the
potential for exposure to contaminated soils, and also mitigates the potential for contaminates migrating
into the groundwater, Alternative 53 meets this criterion more fully than Alternative 52. Both
Alternative 54 and 55 fully meet this criterion. Community exposure to risks during implementation
would be minimal. Worker exposure would be mitigated through institutional controls and normal safety
precautions. Environmental impacts would be mitigated via revegetation.
Implementability-Each of the four alternatives fully meet this criterion since each are
considered fully implementable at 5D15. Alternative 52 is considered the most implementable, since
this alternative involves no construction or excavation, only routine sampling. Alternatives 53, 54 and
55 are considered equally implementable from the standpoint of having reliable technologies and
available equipment and specialists. Because Alternative S3 does not readily allow additional remedial
action to be taken if necessary, it is considered the least implementable of the soil alternatives. Of the
remaining two alternatives (54 and 55), 54 is considered the most easily implemented, since the on-site
construction of a treatment facility would not be required in 54, and the timing of the remedial action
with respect to weather (for the functionality of the compost pile) would not be as critical.
Co~t-Alternative 5 I does not have any costs associated with it. The next least
expensive alternative is 53 ($470K), followed by 54 ($479K), 55 ($S24K), and 52 ($S35K). All costs
are in present value.
OU 6 ROD, Final
4-28
January 1997
"..:
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Modifying Criteria
Modifying criteria consider state and community concerns.
State Acceptance-The State of Alaska has been involved in the development of
alternativc:s for SO 15 and concurs with the USAF and the USEP A in the selection of excavation, thermal
treatment, and backfilling (Alternatives S4) for the contaminated shallow soils at SOlS. As discussed in
Section 4.4.3, high-vacuum extraction is selected for remediation of the groundwater. This technology
will also remediate the deep soil contamination at SOlS; therefore, bioventing is not included in
Alternative S4 for SOlS.
Community Acceptance-All of the alternatives were presented to the public in the
Proposed IPlan. Based on the comments received during the public comment period, the public has no
preference: of alternatives.
4.5
Selected Remedy for SD15
The selected remedy for SOlS includes Alternative 04 for groundwater and deep soils
(high-vacuum extraction with institutional controls and long-term monitoring) and Alternative S4 for
shallow soils (excavation, thermal treatment, and backfilling). The selected remedy is hereafter referred
to as Alternative 04/S4. This remedy best meets the nine CERCLA criteria. It protects human health
and the environment, and complies with ARARs. It is effective at reducing contamination both in the
short term and long term, and is implementable, cost-effective, and acceptable to the public and the State
of Alaska. This alternative provides an appropriate level of treatment to reduce risks and comply with
ARARs. Modeling showed that cleanup can occur within a reasonable time (5 years for groundwater and
deep soils, less than I year for shallow soils). The known sources of contamination have been
controlled,. so they are no longer a threat. High-vacuum extraction will extract contaminated
groundwater, free product, and contaminated soil vapors from the subsurface at a fast rate. Contaminants
will be removed from the groundwater, and the groundwater will be reinjected into the subsurface soil
away from the contaminated aquifer. Low-temperature thermal desorption will permanently remove
contam inants from the excavated shallow soils so that these soils can be returned to SO 15.
SOlS:
Alternative 04/S4 was selected because it best provides the following specific benefits at
.
Contaminated shallow soils will be removed and treated so risk to human health will be
eliminated.
.
Remediation of shallow soils will be completed in about 3 months; therefore,
contaminants will not be able to migrate further or act as a continuing source for
contamination in the perched aquifer.
.
High-vacuum extraction strips contaminants from deep soils so contaminants will not
migrate to groundwater in the future.
.
Active treatment of the perched aquifer will prevent contaminants from migrating to the
deep aquifer. .
.
High-vacuum extraction is the least expensive active treatment for groundwater.
January 1997
4-29
au 6 ROD, Final
-------
the following:
.
High-vacuum extraction remediates deep soils and groundwater simultaneously; thus,
separate treatment for deep soils (e.g., bioventing) is not needed.
Specific components of the selected remedy are illustrated in Figure 4.5-1 and consist of
Percbed Aquifer Groundwater at SOlS:
.
Institutional controls on land use and water use, as specified in the Base Comprehensive
Plan, will restrict access to the contaminated groundwater throughout SDI5. Installation
of wells in the contaminated plume for residential, industrial, or agricultural use will be
prohibited by the Base Comprehensive Plan until cleanup levels have been achieved.
.
Groundwater in the perched aquifer at SD 15 will be treated by a high-vacuum extraction
process to remove fuel related contaminants and HVOCs.
.
Recoverable quantities of free product found on top of the water table at SD 15 will be
removed through the high-vacuum extraction process.
.
Treated water will be reinjected into the subsurface beyond the boundary of the
contaminated aquifer. Reinjected water will be regularly monitored to ensure it meets
cleanup and risk requirements.
.
Groundwater remaining above cleanup levels will continue to be monitored semi-
annually and evaluated annually to determine contaminant migration and to track the
progress of the high-vacuum extraction treatment, as well as to provide an early
indication of unforseen environmental or human health risk. Five-year reviews will also
assess the protectiveness of the remedial action, including an evaluation of any changed
site conditions, as long as contamination remains above cleanup levels.
.
When two consecutive groundwater monitoring events indicate contaminant
concentrations are below cleanup levels, the high-vacuum extraction system will be shut-
off. Semi-annual monitoring will continue for another year, and subsurface soil samples
will be collected. If levels are confirmed to be below cleanup levels one year after the
system was shut-off, no further remedial action will be required. If contamination is
present in any of the samples, the system will be restarted. or another remedial option
will be considered.
.
During the final round of groundwater monitoring, samples will be collected and
analyzed for all constituents that exceeded MCLs during the 1994 investigation
including VOCs and arsenic. These results will be evaluated before a final decision is
made that groundwater meets all cleanup requirements. .
.
All groundwater is expected to be cleaned up within 5 years.
Deep Aquifer Groundwater at SOlS:
.
No further action is required for the deep aquifer groundwater at SDI5.
4-30
January 1997
OU 6 ROD, Final
-------
....
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High-Vacuum Extraction, with Institutional Controls
and Long-Term Monitoring.
Excavation, Thermal Treatment, and Backfilling
of Shallow Soils. Deep Soil Treated by High-Vacuum
Extraction of Groundwater.
Figure 4.5-1. Selected Alternative for SD15
-------
Soil at SDIS:
.
Shallow soils (less than 5 feet deep) with contamination above cleanup levels will be
excavated, removed, and thermally treated to eliminate fuel-related contaminants. After
treatment, no further action will be required for the shallow soils.
.
Deep soils at SOlS will be actively treated through air stripping associated with the
high-vacuum extraction process described for the perched aquifer groundwater.
.
Soils with contamination above cleanup levels will be sampled one year after system
start up and every 3 years thereafter to evaluate contaminant migration and timely
reduction of contaminant concentrations by high-vacuum extraction. If cleanup levels
are not being achieved, further remedial action will be evaluated. This will include
5-year reviews to assess the protectiveness of the remedial action, including an
evaluation of any changed site conditions, as long as contamination remains above
cleanup levels.
.
When two consecutive groundwater monitoring events indicate contaminant
concentrations are below cleanup levels, the high-vacuum extraction system will be shut-
off. Semi-annual monitoring will continue foranother year, and subsurface soil samples
will be collected. If levels are confirmed to be below cleanup levels one year after the
system was shut-off, no further remedial action will be required. If contamination is
present in any of the samples, the system will be restarted, or another remedial option
will be considered. .
.
All soils are expected to be cleaned up within 5 years.
A treatability study for high-vacuum extraction is currently in progress. High-vacuum
extraction will be implemented until cleanup levels have been achieved. Groundwater and soil modeling
predicts cleanup levels will be achieved in about 5 years. Groundwater will be monitored twice a year to
evaluate the progress ofthe high-vacuum extraction system. Deep soils will be sampled after I year and
every 3 years thereafter as long as contamination remains above cleanup levels. Further response
actions, coordinated with the regulatory agencies, may be considered if high-vacuum extraction is
determined to be ineffective.
The selected remedy for shallow soil.s was implemented in 1996. Approximately t 70
cubic yards of fuel-contaminated soil was excavated from four contaminated areas, treated, and used to
backfill the excavations. Confirmation samples indicate that two of the areas are now below cleanup
levels. The other two areas still have elevated levels of contamination and will, therefore, be included in
the high-vacuum extraction treatability study. Further soil excavation will only be planned if necessary
after evaluation of the treatability study results.
Because the remedy will result in contaminants remaining on-site above health based
levels, a review will be conducted within 5 years after commencement of remedial action. The review
will ensure that the remedy continues to provide adequate protection of human health and the
environment. The cleanup levels to be achieved (i.e., remediation goals) through the selected remedy for
COCs at SD,I5 are presented in Table 4.5-1. MCLs were used as the groundwater remediation goals.
One COC at SD15 (t,t,2,2-tetrachloroethane) does not have an MCL and, therefore, does not have a
4-32
January t 997
OU 6 ROD, Final
-------
remediat;ion goal. Cleanup of I, I ,2,2-tetrachloroethane will be complete when all other HVOCs have
met MCLs.
The selected remedy includes provisions for the preparation of a workplan for continued
environmental monitoring of the affected media. This workplan will include specific details regarding
the number and location of monitoring points, as well as guidelines for eliminating select monitoring
points as cleanup occurs. Environmental monitoring will be discontinued at SD IS when the remediation
goals have been satisfactorily achieved (Table 4.5-1). This detennination will be made jointly by the
USAF, the USEPA, and the State of Alaska pursuant to the Federal Facility Agreement.
Table 4.5-1
Identification ofCbemical-Specific ARARs and Remediation Goals, SD15
Elmendorf AFD, AK
Maximum Remediation Basis for
LDcatioD Chemical CODcentration Goal Remediation Goall.1
Groundwater (Perched Aquifer):
SDI5 Benzene 1430 j!gIL 5j!gIL MCL
Elhylbenzene 713 j!gIL 700 j!gIL MCL
Toluene 3640 j!gIL 1000 j!gIL MCL
1,1,2- Trichloroethane 6.97 j!gIL 5 j! gIL MCL
1,2-0ichloroethane 5.92 j!gIL 511gIL MCL
Trichloroethene 143 j!gIL 5j!gIL MCL
Shallow Soils (0-5 feet bgs):
SOlS GRO 33,000 mglkg 1000 mglkg ACM, Level 0
ORO 10,000 mglkg 2000 mglkg ACM, Level 0
BTEX 168 mglkg 100 mglkg ACM. Level 0
Deep Soils (>5 feet bgs):
SOlS GRO 5200 mglkg 1000 mg/kg ACM, Level 0
ORO 6000 mlVk~ 2000 mlVk~ ACM, Level 0
I Maximur~ Con~inant Level (MCL); 40 CFR ~ 141.61 for Federal MCLs, and 18 MC 80.070 for State MCLs. Federal and
State MCLs are identical for the COCs.
2 Alaska Cleanup Matrix (ACM); 18 MC 78.315.
4.5.1
Statutory Determinations
The selected remedy satisfies the requirements under Section 121 of CERCLA to:
.
Protect human health and the environment;
.
Comply with ARARs;
.
Be cost effective; and
January 1997
4-33
OU 6 ROD, Final
-------
.
Utilize pennanent solutions and alternative treatment technologies to the maximum
extent practicable.
Protective or Human Healtb and tbe Environment
The selected remedy is protective of human health and the environment. The current
points of exposure are limited to surface soil. Excavation of contaminated surface soil will eliminated
this risk. Institutional controls will protect against the potential risk by assuring that the contaminated
soils will not come in contact with people until RAOs have been met.
Risks were calculated using assumptions regarding exposure pathways and the time
receptors were exposed to the contaminants. Each exposure was estimated conservatively in a manner
which tends to overestimate the actual risk. Risk management decisions were made considering the
uncertainty in the assumptions used in the risk assessment. At SO 15, the shallow groundwater is not
used and is not expected to be used in the future, so existing risks and potential risks are significantly
less than the worst-case risk.
There are no direct current receptors for groundwater at 5015, but the perched
contaminated groundwater could migrate to the deeper aquifer. The perched aquifer and deep soil
contamination will be remediated with high-vacuum extraction under this selected remedy. Institutional
controls will protect against the potential risk to human health by ensuring that contaminated perched
aquifer groundwater will not be consumed by people until cleanup levels (MCLs) are met. The time
required to achieve MCLs is not known, but could be as short as 5 years based on groundwater modeling
results.
Applicable or Relevant and Appropriate Requirements (ARARs)
Cbemical-Specific ARARs - Chemical-specific cleanup levels (i.e., remediation goals)
for 5015 are identified in Table 4.5-1. The Maximum Contaminant Levels (MCLs) e'stablished for
drinking water under State and Federal laws are relevant and appropriate to groundwater contaminants of
concern at SD IS as a chemical-specific regulation. Semi-annual groundwater monitoring at SO 15 will
document compliance with MCLs. High-vacuum extraction at SO 15 will reduce groundwater
contamination.
For petroleum contaminated soil that will be remediated, specific cleanup levels
indentified as "Level 0" in the Alaska Cleanup Matrix (ACM), 18 AAC 78.315, are relevant and
appropriate (Table 4.5-1). The general ACM guidelines (18 AAC 78.315) and the ACM scoring matrix
are not relevant and appropriate for 5015. Excavation and high-vacuum extraction at 50,15 will reduce
soil contamination. Confinnation sampling after I year and every 3 years thereafter until high-vacuum
extractiol) is complete will document that cleanup goals have been achieved.
Location-Specific ARARs - There are no specific ARARs which must be met because
of the location of the contamination and remedial actions at SO 15.
Action-Specific ARARs - Installation of the reinjection well will be completed in
accordance with the underground injection control program standards (AS 31 and 20 AAC 25).
Additionally, the off-site disposal rule (40 CFR ~ 300.440) is relevant and appropriate to the selected
remedy. Any hazardous substance, pollutant, or contaminant identified during the implementation of the
selected remedy will be disposed of in accordance with this regulation. Action-specific ARARs for
5015 are identified in Table 4.5-2.
OU 6 ROO, Final
4-34
January 1997
-------
Table 4.5-2
Identification of Action-Specific ARARs, SD15
Elmendorf AFB, AK
Standard,
Requin:meot, Criteria, or Citation Description Documentation
Limitatjon
National Oil and Hazardous 40 CFR Establishes procedures for planning Relevant and appropriate if
Substanc(:s Pollution 9 300.440 and implementing off.site transfer hazardous substances,
Contingency Plan--Off-Site of any hazardous substance, pollutants or contaminants are
Disposal Rule pollutant, or contaminant. transferred off site during
implementation of the selected
remedy.
State or Alaska
Undergrolund Injection AS 31; and Establishes regulations for drilling. Substantive requirements are
Control Program Standards 20 AAC 25 relevant and appropriate to
SD 15 because of the proppsed
reinjection of treated
groundwater.
AAC
AS
CFR
- Alaska Administrative Code
- Alaska Statute
- Code of Federal Regulations
Cost Effectiveness
The selected remedy is the most cost effective of the alternatives because it affords over-
all effectiveness proportional to its costs. Alternative S4 (excavating, thermal treatment, and backfilling)
was chosc;:n for the shallow soils to prevent migration of contaminants to groundwater. Alternative S4
costs slightly more than Alternative S3, but Alternative S4 will not require yearly maintenance.
Alternative G4 is about three times more expensive than Alternative G2; however, it will also remediate
the groundwater in about one-third of the time as Alternative G2. Additionally, Alternative G4 will
remediate the con"taminated deep soils.
Utilization of Permanent Solutions and Alternative Treatment Technologies
to tbe Maximum Extent Practicable
The USAF and the USEPA, with concurrence from the State of Alaska, have determined
that the sdected remedy represents the maximum extent to which permanent solutions and treatment
technologies can be used in a cost-effective manner at SD 15. Of those alternatives that are protective of
human health and the environment and comply with ARARs, the USAF and the USEPA have determined
that the sdected remedy provides the best balance of tradeoffs in terms of long-term effectiveness and
permanence; reduction in toxicity, mobility, or volume achieved through treatment; short-term
effectiver'less; implementability; cost (as discussed in the preceding section); the statutory preference for
treatment as a principal element; and considering State and community acceptance. The selected remedy
will permanently remove the contaminants from the affected media so that the media can be returned to
the site (i "e., extracted groundwater will be reinjected and excavated soils will be backfilled). The State
of Alaska concurs with these determinations.
January 1997
4-35
OU 6 ROD, Final
-------
Preference for Treatment as a Principal Element
The selected remedy satisfies this statutory preference by using high-vacuum extraction
to treat contaminated groundwater and deep soils. Additionally thermal treatment will be used to reduce
contamination in shallow soils. .
Documentation of Significant Changes
. The Proposed Plan listed soil and groundwater contaminants with concentrations in
excess. of cleanup guidelines. For groundwater, this Hst was sHghtly different from the list ofCOCs
presented in this ROD. 1,1,2,2- Tetrachloroethane was included in the groundwater COCs since, while
not exceeding a cleanup goal, it did contribute to significant risk. This change did not affect the choice
of alternatives at SO 15. Therefore, the selected remedy for groundwater was the preferred alternative
presented in the Proposed Plan (Table 7 of the Proposed Plan).
4.5.2
During the preparation of the OU 6 ROD, the ACM guidelines were reexamined and
consensus was reached between the USEPA, the USAF, and the State of Alaska that ACM Level 0 was
appropriate at SO 15. This change did not affect the identification of COCs, nor did it affect the choice of
alternatives. Therefore, the selected remedy for soils was the preferred alternative presented in the
Proposed Plan (Table 7 of the Proposed Plan). All changes were a logical outgrowth of the Proposed
Plan.
OU 6 ROD, Final
4-36
January 1997
-------
SECTION FIVE
-------
5.1- ]
5.1-2
5.1-3
5.2-1
5.3-1
5.3-2
5.3-3
5.5-1
TABLE OF CONTENTS
Page
5.0
SI)URCE LF02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1.1 Land Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .'. . . . . . . . . . . 5-1
5.1.2 Hydrogeology and Groundwater Use. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 5-1
Site History .and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .'. . . . 5-3
5.2.1 Identification of Activities Leading to the Current Contamination
at LF02 [[[ 5-6
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . . 5-6
5.3.1 Nature and Extent of Contamination ............................... 5-6
5.3.2 Risk Evaluation. . . .. ...... .. .... ...... .... . . . . . .... . . . . . .. . . . ..5-14
5.3.3 Conclusions.... " . ............. ......... . . .. . .. '" . .. . . . . . .. . . 5-16
Remedial Action Objectives, Alternatives, and Comparative Analysis
for LF02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22
5.4.1 Remedial Action Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22
5.4.2 Groundwater Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-22
5.4.3 Summary of Comparative Analysis of Groundwater Alternatives. . . . . . . . . 5-23
5.4.4 Soil Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-25
5.4.5 Summary of Comparative Analysis of Soil Alternatives. . . . . . . . . . . . . . . . 5-26
Selected Remedy for LF02 ............................................. 5-26
5.5.1 Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-29
5.5.2 Documentation of Significant Changes. . . . . . . . . . . . . . . . . . . . . . . . .. '. . . 5-32
5.2
5.3
5.4
5.5
LIST OF FIGURES
Page
LOI:ation Map for Source Area LF02. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Potentiometric Surface of the Glacial Outwash Plain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
Conceptual Hydrogeologic Model for LF02 and SD73 ..............:............... 5-5
Contaminant Release Mechanisms and Pathways for Exposure at LF02 and SD73 """" 5-7
Chilorinated Solvent Plume in the Groundwater at LF02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19
An:as of Exposed Landfill Waste at LF02 ....................................... 5-20
Ar(:as of Soil Contamination at LF02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-21
-------
5.3-1
5.3-2
5.3-3
5.3-4
5.3-5
5.4-1
5.5- t
LIST OF TABLES
Page
Summary of Groundwater Analytical Results for Source LF02,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8
Summary of Surface Soil Analytical Results for Source LF02,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10
Summary of Subsurface Soil Analytical Results for Source LF02,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12
Summary of Human Health Risks at LF02, Elmendorf AFB; AK . . . . . . . . . . . . . . . . . . . . . . 5-15
Summary of Contaminants of Concern at LF02,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18
Cost and Time to Cleanup for Groun~water Alternatives for LF02,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23
Identification of Action-Specific ARARs, LF02, Elmendorf AFB, AK ................. 5-31
II
-------
Section 5.0
SOURCE LF02
The following subsections describe the physical description, land use, groundwater use,
and hydrogeology ofLF02. The identification of activities which led to the current contamination at
LF02 is also included. The discussion of the regulatory and enforcement history ofLF02, the role of the
response action at LF02, and community participation in the response action are included the general
au 6 discussion in Section 1.0.
5.1
Site Description
Source LF02 is a landfill located in the vicinity of the Boniface Gate and the Federal
A viation Administration (FAA) Air Traffic Control Center in the southeastern comer of Elmendorf AFB
(see Figure: 1.1-2). This source area is partially located on a bluff which s~parates the main floodplain of
Ship Creek from an upper stream terrace. The bluff itself is associated with a change in elevation of
approximately 30 to 40 feet, with the upper terrace being at an elevation of approximately 190 feet above
mean sea k~vel. The southern portion of the landfill is located on the upper terrace, while the northern
portion of 'the site extends beyond the base of the bluff into the lower floodplain terrace. A general site
map ofLF02 is presented as Figure 5.1-1.
This source area was reportedly used to dispose of hard fill, construction rubble, scrap
metal, and general refuse between 1940 and 1942. It appears that the landfill was originally a natural
bluff face that was cleared away for debris disposal. Debris was dumped off of the bluff, and eventually
bulldozers and other equipment pushed debris out to the locations now found at the site. Based on aerial
photographs, landfill activities appeared to have ceased prior to 1950. The physical shape of the landfill
reflects the location of the debris. The majority of the landfill is probably 10 to 20 feet thick. No final
cover was applied to the waste.
The landfill has been overgrown with trees and vegetation since the mid-1950s. On a
site visit conducted by the USAF and the USEPA in October 1993, it was noted that the area is currently
densely vegetated, and that substantial surficial accumulations of miscellaneous metallic debris
(including empty drums) are present.
5.1.1
Land Use
LF02 is currently designated as a "restricted use area" in the Base Comprehensive Plan.
This designation provides for recreational use of the parcel (cross country skiing, etc.) and for
construction of unmanned facilities such as a parking lot, storage building, or taxiway, but prohibits the
construction of any sort of manned facility such as an office building or a residence. Drilling into the
shallow aquifer is also restricted by the Base Comprehensive Plan. As a former landfill, LF02 will
maintain this designation indefinitely.
There are no known historic buildings, archeological sites, wetlands, floodplains, or rare
or endangered species at LF02. The area between LF02 and Ship Creek is a floodplain.
5.1.2
Hydrogeology and Groundwater Use
The discussions of the geologic and hydrogeologic settings for Sources LF02, LF03, and
SD73 have been combined because of their similar hydrogeologic regimes and close proximity on the
glacial outwash plain. The general site map for LF02 is presented as Figure 5.1-1. Site maps for LF03
January 1997
5-1
au 6 ROD, Final
-------
o.
c )
0\ L-L
~
o
5'
'TI
:i' "'--,
~
V.
I
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.....
~
c::
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~
-
\0
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-...J
North
c
l
\
ELMENDORF AFB
LEGEND
SCALE
CT> 0 150 300 w
c: t-
..Y '--- ------, V>
~ N
<> Feet a
a.. ...
...J
-------
Figure 5.1-1. LocatioJL...Map for Source Area LF02
-------
and son are presented as Figures 6.1-1 and 7.1-1, respectively. For a more general description of
Elmendorf AFB geology and hydrogeology see Section 1.0 of this document, or the au 6 RIffS
(USAF, 1996b).
Sources LF02, LF03, and S073 are all situated on late Quaternary glacial outwash
deposits. Based on regional information, this outwash is believed to overlie silt and clay units of the
Bootlegg€:r Cove Formation, which act as an aquitard between the shallow, unconfined, aquifer and a
deep confined aquifer. The Bootlegger Cove Formation was not encountered at these source areas during
the OU 6 RI.
The subsurface geology at LF02 consists of well-graded sandy and silty gravels overlain
by near surface silt and peat deposits. The sandy and silty gravels are the matrix for the shallow aquifer
underlying the site. At LF03, similar near surface silts overlie gravels and sands. The sand and gravel
. unit in which the shallow aquifer is present appears to be fairly continuous in the vicinity of this source
area. The subsurface geology underlying S073 consists chiefly of gravelly sands, with interbedded silty
sand units, overlain with a thin surface layer of silty clay. The shallow aquifer at 5073 resides in the
coarser-gr,ained fraction of these lithologies; however, the aquifer beneath S073 is of generally lower
yield than at LF02 or LF03. The shallow aquifer at a/l three outwash plain source areas is believed to
overlie the: Bootlegger Cove Clay.
A potentiometric surface map for the outwash plain south of Ship Creek is presented as
Figure 5.1..2. Groundwater flow across the LF02 area is west-northwest, and discharges into a large
marsh loc21ted 300 feet west of the landfill. From the marsh, water flows at and below ground surface,
discharging into a channel which empties into Ship Creek. Groundwater flows northwest across the
LF03 land'fill, then bends gently to the west. Localized steepening of the water level contours can be
. observedj'lJst to the north of Source LF03. These are likely associated with a finer-grained composition
of the aquifer in this area. At 5073, groundwater flows in a gentle arc from northwest to west. A
change in groundwater flow direction toward the west and southwest is associated with the nearby
presence of the bluff that partially comprises Source LF02.
The hydraulic gradient in the glacial outwash plain to the south of Ship Creek averages.
approximately 53 feet per mile. The gradient at the different au 6 source areas differs from east to west.
In the vicinity of Source LF03, the groundwater gradient is approximately 80 feet per mile. At S073 and
LF02, the gradient flattens to approximately 42 feet per mile. Based upon slug test data from wells over
the entire a.rea, the hydraulic conductivities in the shallow aquifer were relatively high, and ranged from
2.16E-2 to 8.37E-3 em/sec. These findings are typical of glacial outwash deposits. A generalized
hydrogeologic conceptual model for LF02 and S073 is presented as Figure 5.1-3. The hydrogeologic
conceptual model for LF03, prepared separately, is presented in Section 6.1 as Figure 6.1-2.
The groundwater in the shallow aquifer at these sites is not used for any purpose on base.
Its future use, even if the aquifer was uncontaminated, is generally limited because of the higher yield of
the deeper confined aquifer below the Bootlegger Cove Clay. Particularly at S073, the fine-grained
nature of the aquifer material would make the shallow aquifer unsuitable as a drinking water supply
aquifer.
5.2
Site History and Enforcement Activities
The following section identifies the activities which lead to the current contamination at
LF02. The regulatory and enforcement history for LF02 is included in the general discussion presented
January 1997
5-3
au 6 ROO, Final
-------
o
C
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::a
......
v
P
'T1
Er
~
v-
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....
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='
t:
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~
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-1
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N
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",
...,
....
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//11
-~. .,
::::-..
North
~,
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-:- ~.,...:'
/
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,/ -.
, /
/
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-~--:.' -. -
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S Monitor Well Locations
\~O/ w
- Water Level Contours ~
o
w
o
I ......~
tf!!JJ Wetlands Areas
o 1/8 1/4
~.._...-.=.J
Scale in Miles
Figure 5.1-2. Potentiometric Surface of the Glacial Outwash Plain
-------
'-
~ .
c
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~
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100
...J
VI
.
VI
o
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Source 5073
Building 24- 30 I (A6~
~
Source LF02
/ ~;j7
Disposol Pit A
~/ '
Unconfined A '
gr I) qUlfer (
OVe . TYPical! Sand and
below groun Y 30 feet
feet of satu~a:U~foc,e with 50
e thickness.
ID
"!
'"
....
Legend
. Direclion of Groundwater Flow
Figure 5.1-3. Conceptual Hydrogeologic Model (or LF02 and 8073
-------
for au 6 in Section 1.0, as are the discussions of the role of the response action and the community
participation in the response.
Identification of Activities Leading to tbe Current Contamination at LF02
The principal contaminants identified in the soil and groundwater at LF02 include
metals, solvents, fuel-related compounds, and semi-volatile organic compounds. The sources of
contamination at LF02 relate almost exclusively to waste management practices. Fueling and
maintenance practices at a former gun battery facility located upgradient of the site, as well as the
landfilling of various metallic and organic material at LF02, have resulted in contaminant species being
made available for leaching into the soil and groundwater.
5.2.1
Soil contamination at LF02 represents a continuing source for future groundwater
contamination via downward percolation of groundwater through the vadose zone. Seasonal fluctuations
in the water table have resulted in a smear zone being detected at the base of the vadose zone within
LF02. A schematic of the migration pathway of fuels, metals, and solvents through the soil and into the
groundwater for Sources LF02 and SD73 is presented in Figure 5.2-1. The schematic of the migration
pathway of contaminants through the soil and into the groundwater for LF03, prepared separately, is
presented in Section 6.2 as Figure 6.2-1.
Prior to the Rl conducted at LF02 in 1994, LF02 had been addressed under the following
studies:
.
IRP Phase 1111 Records Search and Statement of Work (Engineering-Science, 1983);
.
RCRA Facility Assessment Report (ADEC, 1988); and
.
SERA Phase 1 B Site Assessment (ENSR, 1993).
Landfilling practices at LF02 ceased between 1942 and the early 1950s. The gun battery
located upgradient of the site was inactivated and removed around the same time landfilling at LF02 was
terminated. Abandoned drums and other vessels in the vicinity of LF02 which could also act as potential
contaminant sources were removed and properly disposed of in 1996.
5.3
Site Contamination. Risks. and Areas Requiring Response Actions
This section identifies the areas which were investigated, and those that require remedial
action. These areas were chosen based on the risk that contaminants pose to human health and the
environment. The basis of this analysis is the data collected during the RI which identified the nature
and extent of contamination at LF02. .
5.3.1
Nature and Extent of Contamination
During the RI, samples of soil and groundwater were collected and analyzed for organic
and inorganic constituents. Significant levels of contaminants were detected in both the soil and
groundwater at LF02. These contaminants include fuels and fuel constituents, solvents, metals, and
svacs. The contamination present at LF02 is associated with contaminant transport in the vadose zone,
dissolved aqueous transport, and volatilization. These transport mechanisms are pictorially represented
for LF02 in Figure 5.2-1.
Tables 5.3-1 through 5.3-3 list the frequency of occurrence and maximum concentrations
of all constituents which were detected during the RI in groundwater and soil. The tables
OU 6 ROD, Final
5-6
January 1997
-------
.....
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Building 24-301 (A6)
loIountain View
Resldenllal Area
Seasonal High
Y Water Table
y
Se050nOl low
Water Table
Residual Contamination
CD
'"
.,;
r-:
Dissolved Phose Contamination
...
"-
o
"-
o
w
Figure 5.2-1. Contaminant Release Mechanisms and Pathways for Exposure at LF02 and 8D73
-------
Table 5.3-1
Summary of Groundwater Analytical Results for Source LF02
Elmendorf AFB, AK
Frequeney or Location or
Method Aaalyte MCLI Mnlmum Detections Mnlmum
(unlls) Result Total HIls!
Total Samples Result
Indicator P.r.meten
SW80lSME (l4g1L) Unidentified organics .. 48.1 B 22/22 MW-48
SW801 SMP (",gIL) Unidentified organics .. SS6 B 20/22 MW-48
Xylene (total) 10000 1.73 12/22 LOI
SW6010. Total (mgIL) Aluminum - 0.742 17122 MW-S7
Calcium .- 27 22/22 MW-S7
Iron -- 1.4 . 22/22 MW-S7
Magnesium - 9.7 22/22 MW-S7
Potassium .. 1.16 2/22 MW-S7
Sodium - 4.26 22/22 MW-SS
SW6010. Dissolved Aluminum -- 0.0546 B III L02
(mgfL) Calcium -- 24.2 III L02
Iron -- 0.0253 B III L02
Magnesium - 4.99 III L02
Sodium - 3.S6 1/1 L02
Contaminant Parameten
SW801 SMP (",gfL) Gasoline - S9.4 1/22 LOI
SW8260 (",gIL) Acetone - 14.3 B 22/22 LOI
Benzene 5 0.88 6/22 MW-S3
Chlorobc:nzene -- 0.16 1/22 L03
Ch1oroc:thane -- 0.012 B 2/22 MW-S3
Chloromethane - 4.36 21/22 L03
Dibromomethane .. 0.23 B 4/22 MW-S2
1.2-Dichlorobc:nzene 600 0.37 B 1/22 L04
1.2-Dichloroethane 5 3.S2 12/221 MW-SS
cis-1.2-Dichloroethene 70 0.12 B 4/22 MW-49
lrans-I.2-Dichloroethene 100 0.16 1/22 MW-S2
Ethylbc:nzene 700 0.82 6/22 LOI
Methylene chloride 5 7.84 21/221 L04
1.1.2.2- Tetrachloroethane -- 4S.1 11/22 MW-49
Toluene 1000 3.S8 B 19/22 MW-SJ
Trichloroc:thene S S.39 12/22 MW-49
m&p-Xylene .. I.4S S/22 LOI
o-Xylene -. 0.38 6/22 LOI
SW8270 (JigIL) Dimethylphthalate -- 31.7 8/22 L03
bis(2 - Ethy I hex yl )phthalate 6 11.8 2/22 L03
Naphthalene - 1.32 2/22 L03
SW6010. Total (mgfL) Barium 2 0.0444 22/22 MW-S7
Beryllium 0.004 . 0.00171 B 17/22 MW-48
Man2anese - O.~06 19/22 MW-S7
au 6 ROD, Final
5-8
January 1997
-------
Table 5.3-1
(Continued)
Frequeney of Locltion of
Mdbod ADIlyte MCV Mnlmum DttectiODS Mnlmum
(units) Result Tot.1 Hits!
Total Simple. Result
SW6011), Total (mgIL) Zinc - 0.0194 11122 L04
(continued)
SW742 I, Total (mgIL) Lead 0.015! 0.00732 1/22 LOI
SW60lO, (Dissolved) Barium 2 0.00507 B III L02
(mgIL) Manganese - 0.00911 III L02
J Maximum contaminanllevel (MCL); 40 CFR ~ 141.61 for Federal MCLs, and 18 AAC 80.070 for State MCLs. Federal and Stale
MCLs are identical for the lisled constituentS.
I Frequency "hitS" calculation does nOI include one or more resultS removed from the data sel because they did nol meel QAlQC crileria.
Total $ilmple counl includes all samples analyzed for the indicated parameter.
) From 40 CFR, Section 141.11 for inorganics and Seclion 141.12 for organics (effective I July 1991); however, the lead level iseffective
only unlil7 December 1992. There is no longer an MCL for lead or copper (56 Federal RelZisler 26460, June 7,1991); however, there is
an action level of 0.015 mg/L for lead and 1.3 mgIL for copper.
B - Sample concentralion was less than or equal to the blank UTL.
January 1997
5-9
OU 6 ROD, Final
-------
Table 5.3-2
Summary of Surface Soil Analytical Results for Source LF02
.Elmendorf AFB. AK
Background Depth or Frequency or Location or
Method ACM Upper Maximum DetectiOD
(units) Analyte Guideline I Tolerance Result Muimum Total Hits! Muimum
Umit Results (ft) Total Samples Result
Indicator Parameters
SW9045 (pH unilS) pH -- - 8.02 I 3/3 S5-097
D2216 (percent) Percent moislure -- eo 28.6 3 34/34 $$-106
5W801 5ME (mg/kg) Unidenlified organics 1000 -- 681 2.5 21/22 55-108
(UDRq]
SW80 I 5MP (mg/kg) Unidentified organics 500 - 90.3 2 6/22 MW-52
(UGRO]
SW6010 (mg/kg) Aluminum -- 31183.96 21700 2 22/22 55-091
Calcium -- 8013.23 40700 2.5 22/22 5S-108
Iron -- 43192.35 196000 2 22/22 SS-I09
Magnesium -- 10904.10 10600 3 22/22 S$-099
Potassium -- 845.75 1790 3 22/22 5$-106
Sodium -- 427.05 1460 2.5 21/221 5S-095
Contaminant Parameters
$W8015ME (mg/kg) Diesel 1000 -- 1550 2 1/22 MW-52
5W801 5MP (J.lg/kg) Benzene 500 J - 10.4 B 2 2/22 $5-109
Toluene ......-, -- 13.1 B 2.5 9/22 55-095
Xylene (Iolal) -- J -- 32.3 2.5 6/22 5$-095
5W8240 (j.lg/kg) Acetone -- -- 66.5 BX 2.5 12/22 $S-095
2-Bulanone(MEK) -- -- 17.2 B I 2/22 55-097
Chloroform -- -- 38.3 3 15/22 55-106
I.I-Dichloroelhene -- -- 2.9X 2.5 1/22 S$-108
Methylene chloride -- -- 5.71 B 2 7/22 55-109
S\\'8270 (mg/kg) Benzo(b )tluoranlhene -- -- 0.0627 F 3 1/22 55-098
Benzo(k)tluoranlhene -- -- 0.0627 F 3 1/22 $5-098
Chrysene -- -- 0.0513 3 2/22 55-098
1.2-Dichlorobcnzene -- -- 0.045 3 1/22 $5-106
1.4-Dichlorobenzene - -- 0.0377 3 1/22 55-106
Fluoranlhene -- -- 0.118 3 1/22 55-098
2-Melhylnaphlhalene -- - 0.209 3 6/22 55-104
Naphthalene -- -- 0.477 2.5 5/22 5$-111
Phenanthrene -- -- 0.214 2.5 5/22 $$-111
Pyrene -- -- 0.0795 3 1/22 5$-098
SW6010 (mglkg) Anlimony -- NA 122 2.5 13/25 $$-108
Barium - 196.45 2160 2.5 22/22 $5-108
Beryllium -- 0.76 0.615 2 20/22 $$-110
Cadmium - 2.68 20.4 2.5 4/22 $$-108
Chromium - 48.44 74.8 2.5 22/22 $$-108
Cobalt -- 19.52 14.3 2 22/22 $$-109
Copper -- 31.67 1170 2 22/22 $5-109
OU 6 ROD, Fina]
5-10
January 1997
-------
Table 5.3-2
(Continued)
Background Deptb of Frequency of Location of
MetbcKl ACM Upper Mllimum Detection
(ullilll) Anal)'te Guideline I Tolerance Result Maximum Total HIts! Mllimum
Umlt Results (ft) Total Samples Resllit
5W6010 (mglk~,) Manganese - 929.98 1010 2 22122 55-110
(continued) Molybdenum - NA 18.5 2 20/22 55-109
Nickel .- 50.68 46.6 2.5 22122 55-108
5elenium - 0.54 17.1 2.5 12122 55-III
5ilver - 1.68 6.98 I 6/22 55-097
Thallium - NA 12 2 1/22 55-109
Vanadium - 101.64 118 3 22122 55-106
Zinc - 90.01 1360 2.5 22122 55-108
5W7060 (mglkgl Arsenic - 13.27 28.6 2.5 22122 55-108
5W7421 (mglkg) lead - 10.69 6080 2.5 34/34 55-108
I Alaska Cleanup Matrix (ACM) level C; 18 MC 78.315.
I Frequency "hilts" calculation docs not include one or more results removed from the data set because they did not meet QAlQC criteria. TOlal
sample count includes all samples analyzed for the indicated parameter.
. The ACM Level C guideline for benzene, toluene, ethylbenzene:and xylenes (BTEX) combined is 50.000~glkg.
B - Sample concentration was less than or equal to the blank UTl.
F - Co-
-------
Table 5.3-3
Summary of Subsurface Soil Analytical Results for Source LF02
Elmendorf AFB, AK
OackgrouDd Depth of Frequency of Location of
Method ACM Upper Maximum Detection
(units) ADalyte Guideline I Tolcnncc Relult Maximum Total Rib! Mnimum
Limit Relults (ft) Total Samples Result
Indicator Paramcten
SW904S (pH units) pH - - 1.01 20.5 1/1 MW-48
02216 (percent) Percent moisture -- - 16.2 5 16/16 SS-125
SW8015ME (mglkg) Unidentified organics 1000 - 1480 18 4/4 MW-52
[UORO)
SW8015MP (mglkg) Unidentified organics 500 - 2850 12 214 MW-52
[UGRO)
SW6010 (mglkg) Aluminum - 18116.11 16600 28 4/4 MW-52
Calcium - 10264.39 9040 28 4/4 MW-52
Iron - 38483.64 28500 28 4/4 MW-52
Magnesium -- 14184.34 9850 28 4/4 MW-52
Potassium -- 1114.35 901 22 4/4 MW-52
Sodium - 365.59 164 28 4/4 MW-52
Contaminant Puameten
SW8015MP (J.lglkg) Ethylbcnzene - 2 - 31.9 36 1/4 MW-48
Toluene -- 2 -- 163 12 1/4 MW-52
Xylene (total) - 2 - IS5 P 12 214 MW-S2
SW8240 (lIglkg) Acetone - - 46.98 12 3/4 MW-S2
SW6010 (mglkg) Antimony -- NA 184 S 3n SS-12S
8arium -- 95.93 14.9 36 4/4 MW-48
Beryllium -- 0.64 0.508 28 4/4 MW-S2
Cadmium -- 3.01 0.686 18 1/4 MW-S2
Chromium -- 16.94 29.9 28 4/4 MW-S2
Cobalt - 11.62 9.59 28 4/4 MW-S2
Copper -- 59.84 S4 28 4/4 MW-52
Manganese -- 109.45 603 28 4/4 MW-52
Molybdenum -- NA 1.44 22 4/4 MW-52
Nickel - 11.19 32.1 28 4/4 MW-52
Selenium - 0.48 5.168 18 1/4 MW-S2
Silver -- 1.06 0.334 B 18 1/4 MW-52
Vanadium - 66.16 60.4 28 4/4 MW-S2
Zinc -- 16.11 6S.8 28 4/4 MW-52
SW1060 (mglkg) Arsenic - 9.31 1.63 22 4/4 MW-52
SW1421 (mglkg) Lead - 10.13 6110 S 131\3 SS-118
I Alaska Cleanup Matrix (ACM) Level C; 18 AAC 18.315.
2 The ACM Level C guideline for benzene, toluene, ethylbenzene, and xylenes (BTEX) combined is 50,OOO~g/kg.
B - Sample concentration was less than or equal to the blank UTL.
NA - Not Applicable.
P - Analyte quantitation not confirmed. Results from primary and secondary GC columns differ by greater than a factor of three.
au 6 ROD, Final
5-12
January 1997
. <:
-------
do not include results below the detection limit. The MCLs for groundwater and the ACM guidelines for
soil are also listed on the tables for all constituents. Results are separated between "indicator
parameters" and "contaminant parameters." Indicator parameters primarily include metals classified as
nutrients, and non-speciated fuel constituents such as unidentified diesel range organics (UDRO) which
are unsuitable for use in a risk assessment. 'A detailed discussion of the detennination of the COC for
LF02 is pn:sented in Section 5.3.3. .
Groundwater Contamination at LF02
. Groundwater contaminants at LF02 include primarily low levels of fuel constituents,
metals, solvents, and other volatile organic compounds (Table 5.3-1). Fuel constituents, such as gasoline
and unidemtified organics, were detected in samples from wells at maximum concentrations of 556 J,lg/L
and 59.4 J,lg/L, respectively. The maximum unidentified organic detection was detected in a sample
from MW-48, but the concentration was flagged as being near the level detected in blank samples. This
well is also located upgradient of the actual LF02 landfill. Numerous VOCs were detected in the
groundwate:r, but among these, the highest single detection was for 1, 1,2,2-tetrachloroethane, at
45.1 J,lgIL. Three SVOCs were detected at low levels; with the highest detection for each occurring in
the same wdl (L03). In general, organic groundwater contaminant concentrations at LF02 were
substantially lower than at any of the previously discussed OU 6 source areas.
Several metals were also detected in the groundwater at LF02. These include relatively
low concemrations of barium, beryllium, manganese, and zinc (Table 5.3-1). As at other OU 6 source
areas, a statistical comparison of these metals concentrations was made to available background metals
concentration from the Elmendorf Air Force Base, Alaska. Basewide Background Sampling Report
(USAF, 1993). Based on this evaluation, all metals evaluated in the groundwater at LF02 were
detennined to be at or near background concentrations. The summary statistics for the USGS data,
including the upper confidence limit concentrations used for these comparisons, are presented in
Table 2.3-4.
In addition to sampling groundwater at LF02, seeps were also sampled. Analytical
results indicated low levels of VOCs in the seeps. No MCLs were exceeded.
Soil Contamination at LF02
Soil data from LF02 were evaluated based upon surface and subsurface contaminant
occurrences. Surface soils include all soils collected from depths shallower than 3 feet bgs. Subsurface
soils are those collected from below 3 feet. Tables 5.3-2 and 5.3-3 list the sample depths, maximum
concentrations, locations, and guidelines associated with the ACM for non-UST soil for all contaminant
parameters in the surface and subsurface soil samples at LF02. Results below the detection limits are not
included in the analytical summary tables.
Contamination in the surface soils at LF02 consists almost exclusively of fuels or fuel
constituents" and metals. BTEX constituents were detected in the surface soils (excluding ethyl benzene),
with the ma:
-------
Metals were frequently detected in the surface soils at LF02. A comparison to
background results (Table 5.3-2) indicated that most metals are at or near background concentrations.
One notable exception was lead, which was detected in several samples at concentrations greater than
1000 mglkg, with a maximum concentrations of 6080 mglkg in the 2-2.5 ft bgs interval. As discussed in
Section 5.2.1, landfilling practices are believed to be the source for the lead and other metals detected at
LF02.
The contaminants present in the subsurface soil at LF02 were of generally similar types
and concentrations to those of the surface. SVOCs and metals were the most pervasive contaminants
(Table 5.3-3). As with the surface soils, the highest fuel constituent detections were from the source
upgradient to LF02. With the exception of lead, metals detections were determined to be predominantly
at or near background concentrations based upon a comparison to background concentrations. Lead was
detected in the subsurface at a maximum concentration of 6170 mglkg in the 3 to 5 feet bgs interval. The
background concentrations are included in the soil analytical summary tables. The COCs for soil at
LF02 are presented in Section 5.3.3.
5.3.2 Risk Evaluation
. Based on the concentrations of contaminants detected during the RI, human health and
environmental risk assessments were performed to determine if areas should be considered for remedial
action. All concentrations of coniaminants, including all contaminants of concern, whether exceeding
MCLs, or ACM guidelines or not, were included in the risk assessments. The general discussion of the
human health and ecological risk assessment procedures is presented in Section 2.3.2, and will not be
repeated since the procedures for each of the source areas within OU 6 were identical. Details on the
parameters used in the Health ,Risk Assessment are shown on Table 2.3-5.
Human Health Risk Assessment (lIRA)
Since LF02 is not currently used residentially, a current residential risk scenario was not
evaluated, and only current visitor and trench worker scenarios were applied. Even though the future
land use at LF02 is restricted as specified in the Base Comprehensive Plan, the future residential risk
scenario was evaluated to obtain the most conservative risk information possible.
ELCRs and HIs were calculated to describe cancer and noncancer risks, respectively.
TheELCR is the additional chance that an individual exposed to site contamination will develop cancer
during hislher lifetime. It is expressed as a probability such as 1.0E-06 (one in a million). The HI
estimates the likelihood that exposure to the contamination will cause some negative health effect. An
HI score above one indicates that some people exposed to the contamination may experience at least one
negative health effect.
The calculated risks at LF02 are based upon hypothetical exposure to soil and
groundwater. Seep data were combined with landfill groundwater data to determine risk. The shallow
groundwater aquifer at LF02 is not presently used, and will not be used in the future for supplying
'potable or non-potable water. For carcinogenic soil risk, the calculated results for the future resident
(RME), construction worker, and visitor are listed. Only the future resident scenario (RME) was used to
calculate carcinogenic groundwater risk. Table 5.3-4 summarizes the calculated carcinogenic and
noncarcinogenic human health risks calculated for LF02.
OU 6 ROD, Final
5-14
January 1997
-------
Table 5.3-4
Summary of Human Health Risks at LF02
Elmendorf AFB. AK
Surface Soil (<3 feet) Subsurface Soil
Risk Chemical(s) Driving
Residential Visitor Trench Risk
Scenario. Scenario" Worker Scenarioc
Soil Risk d
Carcinogc:nic 2.3E-OS I.5E-06 <1.OE-06 Arsenic
Non-Carcinogenic 2.8 0.14 NR Arsenic, Manganese
Ground~'ater Risk d
Carcinogc:nic 3.1 E-OS NA NA 1,1,2,2- Tetrachloroethane
1,2-0ichloroethane
Non-Carcinogenic NR NA NA NA
. Excess cancer risks conservatively assumed for 30 years of exposure (drinking groundwater, contact with soil, etc.) by future residents
(Reasonable: Maximum Exposure).
. Excess cancer risks conservatively assumed for 30 ycars of exposure whilc visiting the site under current conditions.
. Exccss cancer risks conservatively assumcd for I year of cxposure during on-sitc construction work (digging, ctc.).
. Risks are calculated by using thc 95% upper confidcnce limits (UCLs) for contaminants prcsent unless the 95% UCL excccdcd thc maximum
concentratic
-------
Cancer risk using the residential RME scenario for groundwater at LF02 exceeds
1.0E-05, The low levels of I, 1,2,2-tetrachloroethane present at the site drive this risk. No
noncarcinogenic risk was identified for groundwater.
Shallow soil carcinogenic RME risk at LF02 exceeds I.OE-05 for the RME scenario, and
I.OE-06 for the visitor scenario. Only the RME noncarcinogenic risk exceeded 1.0. No significant risk
was identified under the trench worker scenario. Soil risk was 100% attributable to metals, which are
believed to be at background concentrations.
Lead was detected at depth in LF02 and evaluated using USEPA's Lead
UptakefBiokinetic Model to determine whether the lead levels present posed a risk. It was initially
determined that the levels present would not pose suffici€mt risk to require action. Subsequently,
additional sampling demonstrated that lead in excess ofUSEPA screening levels is present nearer the
surface at LF02 than was originally thought to be the case (within 2 feet of the ground surface in some
places). Although the model still indicates that the lead should not pose an unacceptable risk, given the
potential for children to play in the area, it appears prudent to add an additional 2 foot soil cover at areas
with elevated lead concentrations to reduce potential exposure.
Ecological Risk Assessment (ERA)
The ERA was performed to determine if the reported concentrations of chemicals or
calculated exposures to plants and wildlife at OU 6 are likely to produce adverse effects. Ecological
effects were evaluated quantitatively by calculating Ecological Q~otients (EQs). The ERA focused on
evaluating potential impacts of the contamination on selected indicator species: the moose, masked
shrew, meadow vole, black-capped chickadee, merlin, and peregrine falcon. . The general discussion of
the ecological risk assessment procedures is presented in Section 2.3.2 and will not be repeated since the
procedures for each of the source areas within OU 6 were identical.
The EQ of 1,0 was exceeded for the meadow vole, masked shrew, and black capped
chickadee in the landfill area due to elevated concentrations of lead, barium, copper, selenium and zinc.
The highest EQs at the LF02 landfill are associated with zinc (up to 1320 for the black capped
chickadee), which drives the ecological risk in this area. EQs were calculated based on shallow soil and
seep contaminant concentrations. Most of the contribution to ecological risk is associated with metals
contamination in shallow soil.
None of the calculated EQs exceeded 1.0 for the moose, peregrine falcon, or merlin at
LF02. The upgradient source at LF02 was not evaluated from an ecological risk point of view because
insufficient information was collected to conduct this evaluation. Furthermore, this area is located next
to a busy road and is mowed and maintained by the base. Therefore, it is an unlikely habitat for wildlife.
Uncertainties Associated with tbe Risk Assessment
. The major assumptions and uncertainty factors for the OU 6 human health and
ecological risk assessments are presented in Section 2.3.2.
5.3.3
Conclusions
The following subsections provide a discussion of the detennination ofCOCs for LF02,
the location and extent of contamination by COCs in excess of preliminary remediation goals, and a
summary statement about the risk to public health, welfare, or the environment if action is not taken at
LF02.
OU 6 ROD, Final
5-16
January 1997
-------
Contaminants of Concern
Constituents exceeding preliminary remediation goals (MCLs for groundwater or seeps,
ACM guidelines for soils) were identified in the Proposed Plan. COCs were developed from the results
of the risk assessment and by considering preliminary remediation goals. Each constituent having an
individual contribution of greater than I.OE-06 carcinogenic (RME) risk, or an HI greater than 0.1 when
the cumulative HI for the site is greater than 1.0, was considered as a COCo In addition, any constituent
exceeding preliminary remediation goals (MCLs for groundwater or seeps, ACM guidelines for soil) was
also considered as a COe. The final COCs for LF02 are shown on Table 5.3-5, with the individual risk
contributed and basis for identifying the COC (risk or regulatory standard).
Only one COC was identified for groundwater at LF02 (Table 5.3-5).
1,1,2,2- Tetrachloroethane was retained as a COC as the principal contributor to carcinogenic risk at the
site. The occurrence of this constituent is presented graphically on Figure 5.3-1. There is no MCL for
1, 1,2,2-tetrachloroethane; therefore, this map is drawn based upon the exceedance of a risk-based
cleanup goal of 0.43 J-tgIL.
Groundwater data from the former gun battery (i.e., static display area) was evaluated as
an upgradient source to LF02. I, I ,2,2- Tetrachloroethane was the only groundwater risk driver from the
static display area. The highest concentration of this constituent at LF02 was detected in a well at the
upgradient edge of the LF02 landfill. Data indicate that the I, I ,2,2-tetrachloroethane in the LF02 area
originated from this former upgradient source. Since the current contamination is adjacent to the landfill
area, all I, 1,2,2-tetrachloroethane in groundwater will be addressed as part of LF02. Data also suggest
that the low levels of I, I ,2,2-tetrachloroethane seen at seep location SP-06 also originated from this same
source; therefore, seep SP-06 will also be addressed along with the LF02 groundwater. The estimated
volume of these areas of groundwater contamination is 3.5 million gallons.
The Proposed Plan identified three groundwater constituents as exceeding MCLs:
methylene chloride, trichloroethene, and bis(2-ethylhexyl)phthalate. These three constituents were not
identified ciS COCs because they did not contribute to significant risk. Metals were also detected in the
groundwatl~r at LF02. Metals were not included as COCs because: (I) their analytical results were less
than MCLs:; (2) their contribution to health risk was insignificant; and (3) their concentrations were
comparable: to background levels.
Uncovered landfill waste at LF02, particularly debris that is exposed at the surface of the
landfill, wa.s identified as an element requiring a response action at LF02. Debris such as old cans,
automotive parts, crushed drums, old piping, etc., are believed to represent a threat to human health or
the environment. As a consequence, exposed landfill waste is listed as a COC for the shallow soils at
LF02. The projected area requiring action is depicted in Figure 5.3-2. The estimated area requiring
action is approximately 4 acres.
In addition to exposed landfill waste, concerns were expressed during the public
comment period for OU 6 over lead levels in the shallow soils (0 to 2 feet bgs) at LF02. While lead was
not originailly retained as a COC at LF02, subsequent evaluation of additional lead data at LF02 indicated
elevated lead levels were present in shallow soils requiring a response action. Because a response action
is required, lead was retained as a COCo The areas requiring a response include all locations where lead
concentrations exceeded 500 mg/kg in samples occurring at a depth of 2 feet or less bgs. Three small
areas meet this criterion. The areas requiring a response action for lead are depicted on Figure 5.3-3.
The estimated volume of lead-impacted soil is 1200 cubic yards.
January 1997
5-17
OU 6 ROD, Final
-------
o
C
0\
;;g
o
P
"T1
5"
~
Table 5.3-5
Summary of Contaminants of Concern I at LF02
Elmendorf AFB, AK
V>
,
Chemical Maximum Maximum Cancer Maximum Hazard Basis for COC Remediation Basis for
Concentration Risk Index Goal Remediation Goal
Groundwater/Seeps:
1,1,2,2. 45.1 j!glL 2.7E-04 -. Contributes to a risk> 0.43 ~glL Risk Based
Tetrachloroethane I.OE-06
Shallow Soils (0-1 feet bgs):
Lead 4937 mg\kg -- -- Lead UptakelBiokinetic -- .-
Model
Exposed landfill waste -. u -- Alaska solid waste -- --
regulations
Deep Soils (>1 feet bgs): (No COCs for Deep Soils)
00
Cancer risk ~ 1.0E-06 or HI ~ 0.1 for sOil or groundwater scenario with a tolallll of ~ 1.0, or concentrations found In excess of regulatory levels. If cancer risk or HI did nol exceed standards, II was
marked as ".....
bgs - Below ground surface
....
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-
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MW-34
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.--=.:'. ._~_--:'--""'-~~.'~'-----~
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ELMENDORF AFB
LEGEND
~ Monilor Well Location
6. Seepage Location
("----"'1 1,1,2.2- T elrachforoethane
"-- Above 0.43 ~Ig/L
Figure 5.3-1. Chlorinated Solvent Plume in the Groundwater at LF02
,i ."
..~:..
...,
,"
,.
,'j
w
'"
(j
':.
SCALE
150
}OO
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SOURCE L
I
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, I
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..-' ~
.-fIII'
--
- >~
, "
/,
'/
------ --
..---.----.. ------.-
- -_.._--~------ ---_.-
Figure 5.3-2. Areas of E~posed Laodfill Waste at LF02
o
-"
WJ
North
LEGEND
-..--.-
Exposed Landfill Waste
Interpreted Natural
Bluff Edge
o
,
SCALE
100 200
- ---'
feet
on
C7I
a;
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ELMENDORF AFB
LEGEND
S ~onitor Well Locotion
. Soil Boring Location
... Surface Soil Sample Location
~ Surfoce Soils with
~ Lead> 500 ppm
.,.,
o
.0
o
) . -~~
SCALE
150
-------
The OU 6 Proposed Plan identified DRO and GRO as soil constituents exceeding
regulatory levels. This fuel-related soil contamination was detected only at static display locations.
GRO and ORO were not identified as COCs since the contamination is several tens of years old, and that
there is no evidence that it has impacted groundwater during the 40 years since the fonner gun battery
was decommissioned. Metals other than lead were also detected in the soils, but their contribution to
health risk was insignificant and the levels detected were at or near background concentrations. Thus,
lead is the only chemical-specific COC for soil at LF02.
Summary
Actual or threatened releases of hazardous substances from LF02, if not addressed by
implementing the response action selected in this ROD, may present an imminent and substantial
endangennent to public health, welfare, or the environment.
Remedial Action Objectives. Alternatives. and Comparative Analysis for LF02
The following subsections discuss the remedial action objectives for LF02, and present a
description of the various alternatives which were evaluated to achieve those remedial objectives. The
results of the detailed comparison made between those alternatives are also presented.
5.4
Remedial Action Objectives
Specific remediation alternatives were developed and evaluated for the areas with
potential risk and that exceeded the preliminary remediation goals identified in Section 5.3.3. Specific
remedial action objectives (RAOs) for LF02 are as follows:
5.4.1
.
Prevent the ingestion and dennal contact of water, and inhalation of vapors while.
bathing, for water having 1, I ,2,2-tetrachloroethane in excess of cleanup goals and/or
resulting in a cancer risk greater than I.OE-06.
.
Mitigate to the extent practicable human dermal exposure with lead contaminated
shallow soils and.exposed landfill waste or debris present on the landfill surface.
.
Preserve existing vegetation and ecological habitat to the extent practicable.
Groundwater Alternatives
As discussed in Section 5.3.3, the primary COC is a halogenated volatile organic
compound (HVOC) in groundwater. The four most promising groundwater alternatives ("G") were
chosen on the basis of the nine CERCLA criteria. These included the following: no action (G 1); long-
tenn monitoring with institutional controls (G2); pump and treat with institutional controls and long-tenn
monitoring (G3); and air sparging with institutional controls and long-tenn monitoring (G4).
Descriptions of Alternatives G 1, G2, and G3, methods for determining time to complete cleanup, and an
explanation of cost estimates are included in Section 2.4.2. .
5.4.2
Alternative G 1 for LF02 is identical to G I for WP 14/LF04 South. Alternative G2 does
not require product removal for LF02 as it does for WP 14/LF04 South, but otherwise this alternative is
identical between these sites. Alternative G3 for LF02 differs in that air stripping would not be included,
product would not be recovered, and water would be discharged to a nearby storm sewer. Alternative 04
is completely different for LF02; therefore, it is described below. Table 5.4-1 summarizes the cleanup
times and costs for the LF02 groundwater alternatives. .
OU 6 ROD, Final
5-22
January 1997
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Table 5.4-1
Costs and Time to Cleanup for Groundwater Alternatives for LF02
Elmendorf AFB, AK
Altelmative Costs (Thousands of $) Time to Cleanup
Capital Annual O&M" Present Value" (yean)
G2 1.71 28.3 383 23
G3 488 32.4 788 0.3
G4 188 40.5 496 0.3
a
b
O&M = Operation and maintenance
Present value discount rate = S%
Alternative G4: Air Sparging witb Institutional Controls and Long-Term
Monitoring
In Alternative G4, air sparging wells would be installed in the area of contaminated
groundwater. Air would be injected into the wells and sparged (blown) into the groundwater below the
water table. As the air passes through the contaminated groundwater, the contaminants of concern would
be stripped from the water phase into the gas phase.
In addition, some of the oxygen would dissolve into the groundwater, creating an aerobic
environmcmt that would enhance biodegradation of some of the remaining contaminants. Some of the
contamiocmts could migrate to the land surface and be emitted to the atmosphere. This alternative also
includes land use restrictions and the monitoring program described in Alternative G2 (Section 2.4.2).
When two consecutive monitoring events indicate contaminant levels are below cleanup levels, the air
sparging system would be turned off. Semi-annual sampling would continue for one more year. The
sample re~iults would be evaluated to determine if the contaminated concentrations had remained below
cleanup levels. If so, the treatment system would be discontinued and no further remedial action would
be required. If contaminant concentrations had rebounded, the treatment system would be restarted.
5.4.3
Summary of Comparative Analysis of Groundwater Alternatives
The comparative analysis describes how each of the groundwater alternatives meet the
CERCLA evaluation criteria relative to each other.
Tbresbold Criteria
Threshold criteria are those that must be met for the alternative to be viable and relate
directly to the statutory determinations discussed in Section 5.5.1. This category includes two criteria:
overall protection of human health and ,the environment and compliance with ARARs.
Overall Protection of Human Healtb and tbe Environment-Alternative G I (No
Action) w,as the only alternative that failed to meet this criterion. This failure was a result of the
alternativ~: not satisfying the RAOs for protection of human health. This alternative is therefore the least
protective.
Alternatives G2, G3, and G4 all meet this criterion since they each monitor the reduction
of contaminants to acceptable levels through active treatment or natural processes. These alternatives
January 1997
5-23
au 6 ROD, Final
'<:
-------
all satisfy this criterion to slightly different degrees. All of the alternatives comply with ARARs. The
primary differences among Alternatives G2, G3, and G4 are: (I) the risks to workers and the community
during implementation of the alternative; (2) the construction and operation requirements of the
alternatives; and (3) Alternative G2 has a longer remediation time. Alternative G2 poses no additional
risks to workers and the community and has no construction or operational requirements, except those
associated with a groundwater monitoring program. Alternative G3 and G4, on the other hand, involve
the extraction of contaminants, and therefore have an increased risk to workers and community.
Workers also incur physical and contaminant exposure risks during the construction and operation of
remedial equipment in these alternatives. These risks are considered very minor and manageable;
however, the remedial actions associated with these risks would only slightly reduce the overall risk at
LF02 and thus provide little benefit.
Compliance with ARARs- The cleanup level for I, I ,2,2-tetrachloroethane is not an
ARAR, but rather a risk-based remediation goal of 0.43 J.lgIL. There are no chemical-specific ARARs
associated with this remedial goal. Alternatives G2, G3, and G4 will eventually completely meet this
goal, but only Alternatives G3 and G4 include active treatment. Alternative G I does not include a
monitoring program; therefore, it would not be known if and when contaminant concentrations
attenuated to meet the cleanup goal.
No location-specific ARARs were identified for this site; therefore, there is no difference
among the alternatives with regards to these ARARs.
Action-specific ARARs would be satisfied for each of the alternatives, so Alternatives
G I, G2, G3, and G4 each meet this criterion for action-specific ARARs. There are fewer action-specific
ARARs associated with Alternatives G I and G2, making them more preferable than Alternatives G3 and
G4. Alternative G3 would involve complying with federal and state wastewater discharge regulations,
and Alternative G4 has air emission limitations requiring compliance. Compliance for both of these
alternatives should be readily achieved but would require more effort than Alternatives G I and G2.
Balancing Criteria
Balancing criteria are the primary basis for comparing alternatives. These criteria relate
the alternative to the site-specific conditions. The no action alternative (G I) is not evaluated based on
the balancing criteria or the modifying criteria, since it did not meet both threshold criteria. Balancing
criteria includes long-term effectiveness and permanence; reduction in toxicity, mobility, and volume
through treatment; short-term effectiveness; implementability; and cost.
Long-term Effectiveness and Permanence-This criterion has to do with long-term
protection of human health and the environment (reduction of risks), and adequacy and reliability of
controls. Long-term management ("controls") would include a five-year review, land use restrictions,
and semi-annual (twice per year) groundwater monitoring. Alternatives G2, G3, and G4 all fully meet
this criterion, since each alternative includes effective long-term management and permanent reduction
of risks through elimination of contamination. The residual risk and long-term monitoring requirements
for these alternatives are very similar, and do not have any significant differences.
Reduction in Toxicity, Mobility, and Volume Through Treatment-Alternatives G3
and G4 fully meet this criterion since both include active treatment processes to remediate groundwater
contaminants. Both provide an active treatment technology that would reduce the toxicity, mobility, and
volume of contaminated media. Alternative G2 does not satisfy this criterion because it does not
propose an active treatment.
OU 6 ROD. Final
5-24
January 1997
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Sbort-term Effectiveness-This criterion evaluates risks to workers, the community,
and the environment during the period of time until remedial action objectives are met. Alternatives G2,
G3, and Gi4 each meet this criterion since each provide adequate protection and risk reduction while
groundwater contaminants are being reduced to acceptable levels. Even though it has a longer
remediation time, Alternative G2 is considered the most effective in the short term because it involves no
additional risks to workers or the community during implementation and operation.
Alternatives G3 and G4 have little differences with regards to short-term effectiveness.
They both have the same anticipated remediation times and pose minor risks to workers and the
community during construction and operation of remedial equipment. Alternative G4 may be considered
slightly le:;s effective because it discharges contaminants to the atmosphere, whereas Altemative G3
captures them on carbon prior to destruction in a commercial incinerator.
Implementability-Each of the alternatives is considered fully implementable at LF02;
therefore, 002, G3, and G4 each fully meet this criterion. Alternative G2 is considered the most imple-
mentable, followed by Alternatives G4 and G3, respectively. Alternative G2 would not require the con-
struction or operation of remedial equipment. However, it has the least reliable technology. The cal-
culated rate of natural contaminant reduction has substantial uncertainties; therefore, the reliability of
this action has substantial uncertainties. Alternative G3 and G4 have actions requiring construction and
operation of equipment, making them more difficult to implement. In terms of the reliability of the
technologi,es, Alternative G3 uses conventional pump-and-treat methods which historically have had
difficulties in achieving drinking water standards particularly in locations where contamination is wide
spread and at low concentrations. Alternative G4 uses a newer technology, which may be slightly less
reliable.
Cost-Alternative G I does not have any costs associated with it. The next least
expensive alternative is G2 ($383K), followed by G4 ($496K) and G3 ($788K). All costs are in present
value.
Modifying Criteria
Modifying criteria consider state and community concerns.
State Acceptance-The State of Alaska has been involved in the development of
alternative!; for LF02 and concurs with the USAF and the USEPA in the selection of Alternative G2,
long-term monitoring with institutional for groundwater at LF02. The Air Force will investigate and
implement other remedial alternatives should the selected remedy prove to be unsuccessful at meeting.
the required cleanup levels.
Community Acceptance-All the alternatives were presented to the community in the
Proposed. Plan. Based on the comments received during the public comment period, the public has no
preference of alternatives.
5.4.4
Soil Alternatives
As discussed in Section 3.3.3, the only COCs for LF02 soils are the exposed landfill
waste and lead in the shallow soils. Only two alternatives were evaluated: no action (SI); and limited
soil cover with removal of surface debris and institutio'nal controls (S2). Lead was not retained as a COC
in the FS; therefore, this alternative did not originally include a soil cover. However, a limited soil cover
was added to this alternative following the Proposed Plan based upon evaluation of additional data and a
comment rt~ceived from ADEC during the public comment period.
January 1997
5-25
au 6 ROD, Final
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Alternative SI: No Action
Evaluation of this alternative isrequired by CERCLA as a baseline reflecting current
conditions without any cleanup. This alternative is used for comparison with the other alternative. This
alternative does not include long-tenn monitoring, controls, or access restrictions; therefore, potential
exposure pathways would not be eliminated. There are no costs associated with this alternative. .
Alternative S2: Limited Soil Cover with Removal of Surface Debris and
Institutional Controls
This alternative includes placing 2 feet of soil over three areas with elevated lead
concentrations in the shallow soils (Figure 5.3-3). Additionally, any landfill debris on top of or
protruding from the ground at LF02 will also be.removed. The soil cover will protect visitors to the site
from exposure to the lead contaminated soils. Additionally, removal of the surface debris will mitigate
exposure to landfill debris without impacting the existing vegetation. LF02 is currently designated as a
"restricted use area" in the Base Comprehensive Plan. This designation provides for recreational use of
the parcel (cross country skiing, etc.) and for construction of unmanned facilities such as a parking lot,
storage building, or taxiway, but prohibits the construction of any sort of manned facility such as an
office building or a residence. As a fonner landfill, LF02 will maintain this designation indefinitely. No
further action would be required as a means of closing the LF02 landfill. The cost for Alternative 82 is
$74,100. There are no annual O&M costs associated with this alternative.
Summary of Comparative Analysis of Soil Alternatives
The placement of the soil cover may impact existing vegetation in some areas, but
because of the limited nature of this action, the RAO of preserving existing habitat to the extent
practicable is considered met. Additionally, removal of surface debris will minimally impact the
vegetation and ecological habitat while meeting the RAO of mitigating human exposure potential.
Limited soil cover with removal of surface debris and institutional controls is considered to be the sole
practical remedy, because more aggressive actions would damage the existing habitat. The addition of a
limited soil cover is based upon a comment received from ADEC during the public comment period.
ADEC has indicated this approach would be compliant with ARARs concerning applying a final cover to
landfilled wastes; doing so will achieve relevant and appropriate state standards for landfill closure
(18 AAC 60.390). The community did not express a preference of alternatives during the public
comment period on the Proposed Plan.
5.4.5
Selected Remedy for LF02
The selected remedy for LF02 includes Alternatives 02 and 82 (Iong-tenn monitoring
with institutional controls for groundwater, and limited soil cover with removal of surface debris and
institutional controls for soils). The selected remedy is hereafter referred to as Alternative 02/82.
Alternative 52 is the sole practical remedy for mitigating exposure to landfill waste and lead
contaminated shallow soils, because it removes or covers the majority of the waste with minimal impact
(0 the existing vegetation and habitat. It is also acceptable to the public and the State of Alaska.
5.5
Alternative 02 best meets the nine CERCLA criteria. It protects human health and the
environment, and complies with ARARs. It is effective at reducing contamination both in the short tenn
and long tenn, and is implementable, cost-effective, and acceptable to the public and the State of Alaska.
This alternative provides an appropriate level of risk reduction measures and compliance with ARARs.
Modeling showed that groundwater cleanup can occur within a reasonable time (23 years). The known
sources of contamination have been controlled, so they are no longer a threat. This remedy will naturally
degrade the residual contamination.
OU 6 ROD. Final
5-26
January 1997
.'"
-------
LF02:
the following:
.
.
.
.
.
.
Alternative G2/S2 was selected because it provides the following specific benefits at
.
Alternative G2 is the most cost effective alternative for groundwater. It costs less than
Alternatives G3 and G4, and it does not involve additional risks to workers or the
community.
.
Institutional controls will protect against potential risk to human health by reducing the
possibility that contaminated shallow aquifer groundwater will be consumed by people
until cleanup levels are met.
..
Covering contaminated surface soils and removing exposed landfill wastes will protect
human health while causing minimal ecological impacts.
Alternative S2 will substantively comply w!th 18 AAC 60.390.
Specific components of the s(tlected remedy are illustrated in Figure 5.5-1 and consist of
Groundwater at LF02 (Including Seeps):
Access to groundwater at LF02 will be institutionally controlled. LF02 is currently
designated as a "restricted use area" in the Base Comprehensive Plan. This designation
provides for recreational use of the parcel (cross country. skiing, etc.) and for
construction of unmanned facilities such as a parking lot, storage building, or taxiway,
but prohibits the construction of any sort of manned facility such as an office building or
a residence. Drilling into the shallow aquifer is also restricted by the Base
Comprehensive Plan. As a former landfill, LF02 will maintain this designation
indefin itely.
Groundwater will be monitored semi-annually and evaluated annually to determine
contaminant migration and to track the progress of contaminant degradation and
dispersion, as well as to provide an early indication of unforseen environmental or
human health risk. Five-year reviews will also assess the protectiveness of the remedial
action, including an evaluation of any changed site conditions, as long as contamination
remains above cleanup levels.
Groundwater monitoring will be discontinued if contaminant levels are below cleanup
levels during two consecutive monitoring events. In that case, no further action for
groundwater will be required.
During the last round of groundwater monitoring, samples will be collected and analyzed
for all constituents that exceeded MCLs during the 1994 investigation, including VOCs
and SVOCs. These results will be evaluated before a final determination is made that
groundwater meets all cleanup requirements.
All groundwater is expected to be cleaned up within 23 years.
January 1997
OU 6 ROD, Final
5-27
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o
c:
0\
~
P
'TI
S.
~
Groundwater
Soil
. "
,
I J
:..::
....
~
c:
~
Long-Term Monitoring with Institutional Controls.
Limited Soil Cover and Removal of Surface Debris.
\C)
.;0
-...J
Figure 5.5-1. SelecMd Alternatives for LF02
-------
Soil at LF02:
.
Access to soil at LF02 will be if'!stitutionally controlled. LF02 is currently designated as
a "restricted use area" in the Base Comprehensive Plan. This designation provides for
recreatio":al use of the parcel (cross country skiing, etc.) and for construction of
unmanned facilities such as a parking lot, storage building, or taxiway, but prohibits the
construction of any sort of manned facility such as an office building or a residence. As
a former landfiH, LF02 wilf maintain this designation indefinitely.
.
A limited soil cover will be applied in three areas with elevated lead concentrations at
LF02. This will eliminate the pathway for contact with the lead contamination. Five-
year reviews will be conducted to evaluate the integrity ofthe cover, evaluate impacts
from any changed site conditions, and assess the continued protectiveness of this
remedial action.
.
Landfill debris on top of or protruding from the ground surface at LF02 will also be
removed as part of the specific remedy for this area.
.
Hazardous materials encountered during the removal event will be handled according to
appropriate regulations. .
.
No further action will be required as a means of closing the LF02 landfill.
The actual time frame for natural contaminant degradation is not known, but
groundwat
-------
Utilize pennanent solutions and alternative treatment technologies to the maximum
extent practicable.
Protective of Human Health and the Environment
The selected remedy is protective of human health and the environment. Risk to human
health from the exposed landfill waste and lead contaminated shallow soils will be reduced by removing
the landfill waste and placing a clean soil cover over the lead contaminated areas. There are no current
points of exposure for the contaminated groundwater. The potential for exposure to contaminated seeps
is very low. Institutional controls will protect against the potential risks by assuring th~t contact with the
contaminated media is minimized until RAOs have been met.
Risks were calculated using assumptions regarding exposure pathways and the time
receptors were exposed to the contaminants. Each exposure was estimated conservatively in a manner
which tends to overestimate the actual risk. Risk management decisions were made considering the
uncertainty in the assumptions used in the risk assessment. At LF02, the shallow groundwater is not
used and is not expected to be used in the future, so existing risks and potential risks are significantly
less than the worst-case risk.
The time required to achieve cleanup levels is not known, but it is estimated to be about
23 years based on statistical analysis of 1994 and 1996 data. Additionally, modeling of contaminant
flow at Elmendorf AFB showed that conditions are not expected to deteriorate at LF02. Over time,
conditions will improve and the model predicts that cleanup objectives will be met.
Applicable or Relevant and Appropriate Requirements (ARARs)
Chemical-Specific ARARs --There are no chemical-specific ARARs for the
groundwater or soils at LF02. The COC for groundwater, 1, I ,2,2-tetrachloroethane, does not have an
MCL; therefore, a risk-based gqal of 0.43 J.lg/L will be used as a remediation goal to detennine if
cleanup has been achieved via natural attenuation. This goal is based on risk calculations assuming a
residential scenario. Semi-annual groundwater monitoring at LF02 will document the progress towards
this goal.
Location-Specific ARARs -- There are no specific ARARs which must be met because
of the location of the contamination and remedial actions at LF02.
Action-Specific ARARs - The Alaska Solid Waste Management Regulations, Closure
Standards for Municipal Solid Waste Landfills (18 AAC 60.390), are relevant and appropriate
regulations for LF02. This regulation requires a 24-inch thick cover, or another thickness approved by
ADEC, for landfills to be closed. Except for the three areas of surface soils with elevated lead
concentrations, ADEC had indicated that the existing cover at LF02 is compliant with state standards for
landfill closure (18 AAC 60.390) concerning applying a final cover to landfilled wastes. ADEC has
approved the selected remedy of a 2-foot thick soil cover at the three areas with elevated lead
concentrations in the surface soils (Figure 5.3-3). This cover does not require grading, but it will be
seeded to promote revegetation.
The off-site disposal rule (40 CFR 9 300.440) is also relevant and appropriate to the
selected remedy. Any hazardous substance, pollutant, or contaminant identified during the
implementation of the selected remedy will be disposed of in accordance with this regulation. Action-
specific ARARs for LF02 are identified in Table 5.5-1. '
OU 6 ROD, Final
5-30
January 1997
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Table 5.5-1
Ideotificatioo of Actioo-Specific ARARs, LF02
. Elmeodorf AFB, AI(
Standard,
Requinment, Criteria, or Citation Description Documentation
Limitation
National Oil and Hazardous 40 CFR Establishes procedures for planning Relevant and appropriate if
Substance's Pollution 9 300.440 and implementing ofT-site transfer hazardous substances,
Contingency Plan--OfT-Site of any hazardous substance, pollutants or contaminants are
Disposal Rule pollutant, or contaminant. transferred ofT site during
implementation of the selected
remedy.
State of A.laska
Alaska Solid Waste ISAAC Provides requirements for closure Requirements are relevant and
Managem:nt Regulations 60.390 of solid waste municipal landfills. appropriate to the landfill at
LF02.
AAC
CFR
- Alaska Administrative Code
- Code of Federal Regulations
Cost Effectiveoess
The selected remedy is the most cost effective of the alternatives because it affords
overall effectiveness proportional to its cost. The anticipated remediation time for Alternative G2 is
23 years; therefore, more active remediation would cost more without being significantly more effective.
The no action alternative for the soils is less expensive than Alternative S2, but it does not meet the
RAOs. Thus, Alternative S2 is the only effective remedy.
Utilizatioo of Permaoeot Solutioos aod Alteroative Treatmeot Techoologies
to the Maximum Exteot Practicable
The USAF and the USEP A have determined that the selected remedy represents the
maximum extent to which permanent solutions and treatment technologies can be used in a cost-effective
manner at LF02. Of those alternatives that are protective of human health and the environment and
comply with ARARs, the USAF and the USEPA have determined that the selected remedy provides the
best balanc:e of tradeoffs in terms of long-term effectiveness and permanence; reduction in toxicity,
mobility, or volume achieved through treatment; short-term effectiveness; implementability; cost (as
discussed in the preceding section); the statutory preference for treatment as a principal element; and,
considering State and community acceptance. Although the selected remedy does not involve active
treatment, it will permanently remove the contaminants through natural, biological break down of the
contaminants into harmless chemical compounds, and will permanently remove exposed debris from the
site. The State of Alaska concurs with these determinations.
Prefereoce for Treatmeot as a Priocipal Elemeot
Because of the substantial additional cost of actively treating groundwater, the potential
for natural degradation in 23 years, and the fact that there are no current receptors of groundwater, long-
term monitoring with institutional controls is a more favorable means of addressing groundwater
contamination than active treatment. The soil contamination at LF02 (i.e., lead contamination and
landfill waste) are not susceptible to treatment; therefore, the waste will be removed and the lead
contamination will be covered to prevent exposure.
January 1997
5-31
OU 6 ROD, Final
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Documentation of Significant Changes
The Proposed Plan lists soil and groundwater contaminants with concentrations in excess
of cleanup goals (ACM guidelines and MCLs). This list is different from the COCs established in
Section 5.3.3. because identification ofCOCs includes evaluation of risk along with comparison to
cleanup levels. The selected remedy was similar to the preferred alternative presented in the Proposed
Plan (Table 7 of the Proposed Plan). The Proposed Plan recommended long-tenn monitoring ofthe
groundwater and removal of surface debris for the LF02 soils. but the selected remedy also includes a
limited soil cover for the lead contaminated shallow soils. The addition of a limited soil cover to address
lead in the shallow soil at LF02 is based upon evaluation of additional data and a comment received from
ADEC during the public comment period. These changes were a logical outgrowth of the Proposed
Plan.
5.5.2
OU 6 ROD, Final
5-32
January 1997
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SECTION SIX
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6.0
6.3
6.4
6..5
6.1-1
TABLE OF CONTENTS
Page
SOURCE LF03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6..1
Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.1.1 Land Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.1.2 Hydrogeology and Groundwater Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
6.2.1 Identification of Activities Leading to the Current Contamination
at LF03 [[[ 6-4
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . . 6-4
6.3.1 Nature and Extent of Contamination ............................... 6-4
6.3.2 Risk Evaluation. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-11
6.3.3 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . '. . . . . . . . . . . . . . 6-13
Remedial Action Objectives, Alternatives, and Comparative Analysis
for LF03 """" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
6.4.1 Remedial Action Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
6.4.2 Groundwater Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 6-14
6.4.3 Soil Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-14
Selected Remedy for LF03 ............................................. 6-14
6.5.1 Statutory Detenn inations ........................................ 6-15
6.5.2 Documentation of Significant Changes. ............................6-15
6.2
LIST OF FIGURES
Location Map for Source Area LF03 ............................................ 6-2
Page
6.1-2
Conceptual Hydrogeologic Model for LF03 ...................................... 6-3
6.2-1
Contaminant Release Mechanisms and Pathways for Exposure at
LF03 and Adjacent Trenches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
6.3-1
LIST OF TABLES
Page,
Summary of Groundwater Analytical Results for Source LF03,
-------
6.3-2
6.3-3
6.3-4
LIST OF TABLES (Continued)
Page
Summary of Surface Soil Analytical Results for Source LF03,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9
Summary of Subsurface Soil Analytical Results for Source LF03,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10
Summary of Human Health Risks at LF03, Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . 6-12
11
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SectiOiIl 6.0
SOURCE LF03
The following subsections describe the physical description, land use, groundwater use,
and hydrogeology ofLF03. The identification of activities which led to the current contamination at
LF03 is also included. The discussion ofthe regulatory and enforcement history of LF03, the role of the
response action at LF03, and community participation in the response action are included in the general
OU 6 disc:ussion in Section 1.0. The detailed discussion of the hydrogeology at LF03 was combined
with the d:escription of the hydrogeology at LF02 and SD73 and is presented in Section 5.1.2. These
discussions were combined because of the close proximity between Sources LF02, LF03, and SD73 on
the glacial outwash plain.
6.1
Site Description
Source LF03 (Figure 6.1-1) consists of a IS-acre landfill located south of Ship Creek.
Specifically, this source area is located west of Hospital Drive (west of the hospital housing area), south
ofOit Well Road, east of Transformer Street, and north of the sewage meter station. This source area is
located 0111 relatively flat terrain at an elevation of225 feet above mean sea level, where the landfill itself
creates a localized topographic high. The regional terrain slopes to the west at about 100 feet per mile.
The landfilll was operated from 1943 to 1957. General refuse and construction rubble generated from
base operations were reportedly disposed of in this landfill.
Three man-made trenches are also located in the vicinity of LF03. Two of these trenches
(approximately 6 feet by 25 feet and 6 by 60 feet) are densely vegetated. The longer of the vegetated
trenches had a central berm dividing it into two sections. The third trench (approximately 15 feet by 40
feet) is virtually barren. Both trench and fill, as well as surface dump operations took place at this source
area. No daily cover was applied at the landfill, and some open burning reportedly took place during the
1950s. As a result of complaints about odor and nuisance, the landfill was closed in 1957. It was
covered with several feet of local soil, which now supports a substantial growth oftrees and shrubs
(USAF, 1996).
6.1.1
Land Use
LF03 is currently designated as a "restricted use area" in the Base Comprehensive Plan.
This designation provides for recreational use of the parcel (cross country skiing, etc.) and for
construction of unmanned facilities such as a parking lot, storage building, or taxiway, but prohibits the
construction of any sort of manned facility such as an office building or a residence. Drilling into the
shallow aquifer is also restricted by the Base Comprehensive Plan. As a former landfill, LF03 will
maintain this designation indefinitely. Permanent inclusion in the "accident potential zone" further
restricts the construction of any aboveground facilities at this location.
There are no known historic buildings, archeological sites, wetlands, floodplains, or rare
or endangt~red species at LF03.
6.1.2
Hydrogeology and Groundwater Use
The discussions of the geologic and hydrogeologic settings for Sources LF03, LF02, and
SD73 havc~ been combined because of their similar hydrogeologic regimes and close proximity on the
glacial outwash plain. The general site map for LF03 is presented as 6.1-1. The hydrogeologic
conceptual model for LF03, showing the main hydrostatigraphic units in the area, is presented as
January 1997
6-1
OU 6 ROD, Final
-------
o
c:
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o
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"T1
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!.
0\
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"
.....
~
c::
~
-
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-J
J
~~ ()
)
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LEGEND
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300
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Figure 6.1-1. Location Map for Source Area LF03
-------
....
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~
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Source Lr03
/
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gravel). TYPic~~:fer (sand and
below ground Y 30 feel
feel of solu ~urfoce wilh 50
ro ed thickness.
Legend
- .. Direclion of Groundwoter now
CD
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on
....
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o
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Figure 6.1-2. Conceptual Hydrogeologic Model for LF03
-------
Figure 6.1-2. For a more general description of Elmendorf AFB geology and hydrogeology see
Section 1.0 of this document. or the OU 6 RIIFS (USAF, 1996).
The groundwater in the shallow aquifer at LF03 is not used for any purpose on base. Its
future use, even if the aquifer was uncontaminated, is generally limited because of the higher yield of the
deeper confined aquifer below the Bootlegger Cove Clay.
6.2
Site History and Enforcement Activities
The following section identifies the activities which led to the current contamination at
LF03. The regulatory and enforcement history for LF03 is included in the general discussion presented
for OU 6 in Section 1.0, as are the discussions of the role of the response action and the community
participation in the response.
6.2.1
Identification of Activities Leading to tbe Current Contamination at LF03
Significant contamination at LF03 is limited to groundwater only, since the landfill itself
has been capped. Significant contamination was also not identified in any of the trenches around LF03.
Constitu"ents detected in the groundwater at LF03 are primarily metals. However, all of
the metals detected are at background concentrations. Low levels of other constituents below MCLs,
primarily solvents. were also detected in the groundwater. Specific sources were not identified for these
constituents. A schematic of the migration path these low level solvents and metals may take through the
soil and into the groundwater is presented as Figure 6.2-1.
Prior to the RI conducted at LF03 in 1994, LF03 had been addressed under the following
studies:
.
IRP Phase 1111 Records Search and Statement of Work (Engineering-Science, 1983);
.
IRP Phase II, Stage 3 Work Plan (Harding Lawson, 1988);
.
RCRA Facility Assessment R~port (ADEC, 1988); and
.
IRP Phase III, Stages 3 and 4, Remedial InvestigationlFeasibility Study (Black and
Veatch, 1990).
Landfilling practices at LF03 were discontinued in 1957 and the area was covered with
clean soil. No other sources requiring action appear to be present at this source area.
6.3
Site Contamination. Risks. and Areas Requiring Response Actions
This section identifies the areas which were investigated, and those that require
remedial action. These areas were chosen based on the risk that contaminants pose to human health and
the environment. The basis of this analysis is the data collected during the RI which identified the
nature and extent of contamination at LF03.
6.3.1
Nature and Extent of Contamination
During the RI, samples of soil and groundwater were collected and analyzed for organic
and inorganic constituents. Both organic and inorganic contaminants were detected in the soil and
groundwater at LF03. These contaminants include low levels of fuel constituents, VOCs, and metals.
OU 6 ROD, Final
6-4
January 1997
-------
......
~
::s
c
~
~
.-
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Trenches and...
fill Areas
Fug(Jllv~ Dusl
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. .
.. ..-
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. . .
"
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Seasonal low
Water Table
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Residual Contamination
Dissolved Phase Contamination
an
Construction Oebris,
Spent Small Arms Ammunition.
and Shop Wastes
overed wilh Natural Soil
-------
The contaminations present at LF03 are associated with contaminant transport in the vadose zone,
dissolved aqueous transport, and volatilization. These transport mechanisms are pictorially represented
for LF03 in Figure 6.2-1.
Tables 6.3-1 through 6.3-3 list the frequency of occurrence and maximum
concentrations of all constituents which were detected during the RI in groundwater and soil. The
tables do not include results below the detection limit. The MCLs for groundwater and the ACM
guidelines for soil are also listed on the tables for all constituents. Results are separated between
"indicator parameters" and "contaminant parameters." Indicator parameters primarily include metals
. classified as nutrients, and non-speciated fuel constituents such as UDRO which are unsuitable for use
in a risk-assessment. A detailed discussion of the determination of the COCs for LF03 is presented in
Section 6.3.3.
Groundwater Contamination at LF03
Groundwater contaminants at LF03 include primarily low levels of fuel constituents,
metals, solvents, and other VOCs (Table 6.3-1). The only fuel constituents detected were unidentified
organics, which were detected in samples at a maximum concentration of 89.3 Ji.g/L. The maximum
unidentified organic detection was in a sample from MW-32A. The concentrations were flagged as
being near the level detected in blank samples. Numerous VOCs including some solvents were detected
in the groundwater, but among these, the highest single detection was for acetone, at 11.2 Ji.g/L. This
concentration was flagged as being near blank concentrations. Two SVOCs were detected at low levels,
with the highest detection being 10.1 Ji.g/L for dimethylphthalate in a sample from MW -32A. In
general, organic groundwater contaminant concentrations at LF03, like at LF02, were substantially
lower than those previously discussed for source areas WP14, LF04, and SDI5.
. Numerous metals were also detected in the groundwater at LF03 (Table 6.3-1). As at
other au 6 source areas, a statistical comparison of these metals concentrations was made to available
background metals concentration from Elmendorf Air Force Base. Alaska Basewide Background
Sampling Report (USAF, ]993). Based on this evaluation, all metals evaluated in the groundwater at
LF03 were determined to be at or near background concentrations. The summary statistics for the
USGS data, including the upper confidence limit concentrations used for these comparisons, are
presented in Table 2.3-4.
Soil Contamination at LF03
Soil data from LF03 were evaluated based upon surface and subsurface contaminant
occurrences. Surface soils include all soils collected from depths shallower than 3 feet bg~. Subsurface
soils are those collected from below 3 feet. Tables 6.3-2 and 6.3-3 list the sample depths, maximum
concentrations, locations, and guidelines associated with the ACM for non-UST soil for all contaminant
parameters in the surface and subsurface soil samples at LF03. Results below the detections limits are
not included in the analytical summary tables.
Contamination in the surface and subsurface soils at LF03 occur at concentrations
below any other sites previously discussed for OU 6, with the possible exception of LF02. The
contaminants present include low levels of metals, fuel constituents, and VOCs.
Metals were frequently detected in the surface and surface soils at LF03. Metals
. oc~urrences, via comparison to background results (Table 6.3-2 and 6.3-3), were determined to be at or
near background concentrations. Fuel constituents (UGRO and UDRO) were detected in both surface
OU 6 ROD, Final
6-6
January 1997
-------
Table 6.3-1
Summary of Groundwater Analytical Results for Source LF03
Elmendorf AFB, AK
Frequency or Location or
Method Analyte MCL' Maximum Detections Mnlmum
(IlnilS) Result TotaJ HIts!
Total Samples Result
Indicatol' Parameters
SW80 I 5ME (1!g!L) Unidentified organics - 51.9 B 10/10 MW-32A
SW80 I 5MP (1!g!L) Unidentified organics -- 89.3 B 8/10 MW-32A
Xylene (tolal) 10000 2.25 6/10 MW-32A
SW6010, TOlal (mgIL) Aluminum - 89.7 10/10 03-03
Calcium - 200 10/10 03-02
Iron - 133 10/10 03-03
Magnesium - 76.4 10/10 03-03
Potassium' - 7..77 7/10 03-03
Sodium - 25.2 10/10 03-03
SW6010, Dissolved Aluminum - 0.0684 B 2/6 03-01
(mgIL) Calcium -- 107 6/6 03-03
Iron -- 0.2-3 6/6 03-03
Magnesium .. 27.2 6/6 03-03
POlassium - U5 4/6 03-03
Sodium -- 22.2 6/6 03-03
Contaminnt Parameters
SW8260 (1!g!L) Acetone - 11.2 B 10/10 03-01
Benzene S 0.32 B 6/10 MW-32A
2-Bulanone(MEK) -- 4.97 B 1/10 MW-32A
Chloroclhane - 0.15 1110 03-01
Chloromethane -- 3.34 7/10 03-0]
Dibromomethane - 0.19 B 1/10 MW -32A
1,2-Dichlorocthane 5 2.71 11101 03-01
Ethylbenzene 700 1.2 1/10 MW-32A
Methylene chloride 5 1.58 B 9/10 03-01
4-Methyl-2-pcntanone(MIBK) -- 2.92 1/10 MW-32A
Toluene 1000 2.59 8/10 MW-32A
m & p-Xylene -- 1.96 1/10 MW-32A
o-Xylene .. 0.54 1/10 MW-32A
SW8270 (lig/L) Dimethylphthalale -- 10.1 2/10 MW-32A
bis(2 - E thy Ihex y I )phthalate 6 1.54 B 1/10 03-01
SW8310 CIIg!L) Acenaphthene -- 0.54 B 1110 03-02
SW6010, TOlal (mgIL) Antimony 0.006 0.0983 1/10 03-03
Barium 2 0.649 10110 03-02
Beryllium 0.004 0.00342 9/10 03-03
Cadmium 0.005 0.00604 1/10 03-02
Chromium 0.1 0.165 6/10 03-03
Cobalt -- 0.0706 4/10 03-02
January 1997
6-7
OU 6 ROD, Final
-------
Table 6.3-1
(Continued)
Frequency of Loution of
Mdhod An.lyte MCLI Muimum Detections M8Iimum
(units) Result Total HIts!
Total Samples Result
SW6010. Tola! (mgIL) Copper 1.3' 0.223 6110 D3-o2
(continued) Manganese - 4.18 9/10 D3-o2
Nickel 0.\ 0.23 S/IO D3-03
Vanadium - 0.254 4/10 D3-o3
Zinc -- 0.282 8/10 D3-03
SW7060. Total (mgIL) Arsenic 0.05 0.0637 7/10 D3-03
SW7421. Total (mgIL) Lead 0.015' 0.0558 5/10 D3-o2
SW6010. Dissolved Barium 2 0.0433 6/6 D3-o3
(mgIL) Beryllium 0.004 0.00136 B 5/6 03-01
Cadmium 0.005 0.00506 1/6 03-03
Manganese - 1.:45 6/6 D3-o3
Zinc - 0.102 1/6 D3-oJ
SW7060. Dissolved Arsenic 0.05 0.00613 1/6 D3-03
(mgIL)
I Maximum contaminant level (MCL); 40 CFR f 141.61 for Fedenl MCLs. and 18 AAC 80.070 for State MCLs. FedenJ and Slate
MCLs are identical for the listed constituents.
I Frequency "hits" calculation does not include one: or more results removed from the data set because they did not meet QAlQC criteria.
TOIaI sample count includes all samples analyzed for the indicated panmeter.
, From 40 CFR, Section 141.11 for inorganics and Section 141 .12 for organics (effective I July 1991); however, the lead level is effective
only until 7 December 1992. There is no longer an MCL for lead or copper (56 Federal Rel!.ister 26460. June 7, 1991); however. there is
an action level of 0.01 5 rng!L for lead and 1.3 mgfL for copper.
B - Sample concenrntion was less than or equal to the blank un.
6-8
January 1997
OU 6 ROD, Final
-------
Table 6.3-2
Summary of Surface Soil Analytical Results for Source LF03
Elmendorf AFB, AK
Background Depth of Freqnency of Location of
Method ACM Upper Mnlmum Detection
(units) Analyte Guideline I Tolerance Result Muimum Total Hits! I Mnimum
Limit Results (ft) Total Samples Result
Indicator Parameters
D2216 (percent) Percent moisture: - - 28 2 3/3 MW-33
5W80lSME (mglkg) Unidentified organics 1000 .- 4.49 B 2 3/3 MW-32
(UDRO)
5W80lSMP (mglkg) Unidentified organics SOO -- 43.6 B 2 2/3 58-29
(UGRO)
SW6010 (mglkg} Aluminum -- 31183.96 22000 2 3/3 MW.33
Calcium - 8013.96 7S80 2 3/3 MW-33
Iron - 43192.35 29300 2 3/3 MW-32
Magnesium - 10904.10 8300 2 3/3 MW-32
Potassium - 84S.7S 1000 2 3/3 MW.33
Sodium - 427.0S 276 2 3/3 MW-33
Contaminant Parameters
SW801 SMP (JIg/kg) Ethylbenzene _2 -- 59.3 2 1/3 MW-33
Toluene _2 - 54.4 2 1/3 5B-29
Xylene (total) _2 - 98.5 2 1/3 MW-33
SW8240 (Jlglkg) Acetone - - 15.5 B 2 1/3 MW-33
2-Butanone(MEK) -- - 7.83 B 2 213 5B.29
Methylene chloride - - 2.03 B 2 2/3 SB-29
m & p-Xylene .- 2 - 38.2 2 1/3 MW.33
o.Xylene _2 .. 14.3 2 1/3 MW-33
SW6010 (mglkg) Barium .- 196.45 87.1 2 3/3 MW.33
Beryllium .. 0.76 0.493 2 3/3 MW-32
Chromium - 48.44 33.3 2 . 3/3 MW-33
Cobal! -- 19.52 10.4 2 3/3 SB-29
Coppcr -- 31.67 36.8 2 3/3 58-29
Manganese -- 929.98 560 2 3/3 SB-29
Molybdenum -- NA 1.31 2 3/3 58-29
Nickel .. 50.68 30.2 2 3/3 SB-29
Selenium -- 0.54 6.59 2 1/3 5B-29
Vanadium - 101.64 75.9 2 3/3 MW-33
Zinc - 90.01 58.5 2 3/3 SB-29
SW7060 (mglkg) Arsenic .- 13.27 8.11 2 3/3 SB-29
5W742 1 (mglkg) lead -- 10.69 6.23 2 3/3 S8-29
I Alaska Cleanup Matrix (ACM) Level C; 18 AAC 78.315.
! The ACM level C guideline for benzene, toluene, ethyl benzene, and xylenes (BTEX) combined is 50,000 jJglkg.
B - Sample concenrralion was less than or equal 10 the blank UTL.
NA - Not applicable.
January 1997
6-9
au 6 ROD, Final
-------
Table 6.3-3
Summary of Subsurface Soil Analytical Results for Source LF03
Elmendorf AFB, AI(
Upper Deptb or Frequency or lAcadoD or
Metbod ACM M8Itimum DekctioD
(uaib) ADalyte GuideliDe I Tolennee Result M8Itimam Total Hits! M8Itimum
Limit Results (rt) .Total Samples Result
Indicator Parameters
D2216 (percent) Percent moisture - - 13.2 22 16/16 MW.33
SW8015ME (mg/kg) Unidentified organics 1000 - 5.168 22 7n MW-32
[UDRO]
SW8015MP (mg/kg) Unidentified organics 500 - 0.554 8 22 5/9 S8-29
(UGRO)
SW6010 (mg/kg) Aluminum - 18116.77 18700 4 7n MW-33
Calcium - 10264.39 13200 18 7n MW-33
Iron - 38483.64 32400 4 7n MW-33
Magnesium - 14784.34 9880 4 7n MW-33
Potassium - 1114.35 1180 18 7n MW-33
Sodium - 365.59 240 18 7/7 MW-33
Contaminant Parameters
SW8015MP bag/kg) Ethylbenzene .. ~ - 120 22 3/9 MW.33
Toluene -' - 198 7 7/9 5B-29
Xylene (total) _2 - 209 22 3/9 MW-33
SW8240 (Jlg/kg) Acetone - - 32.28 12 5/9 MW-32
2.Butanone(MEK) - - 9.468 7 7/9 SB-29
Methylene chloride - - 3.42 B 17 9/9 MW-32
m & p.Xylene -~ .. 14.4 12 4/9 MW-33
o-Xylene .. ~ - 6.52 . 12 1/9 MW-33
SW60IO (mg/kg) Antimony - NA 3.75 B 16 1/7 MW-33
Barium - 95.93 63.4 4 7n MW-32
Beryllium - 0.64 0.516 4 7/7 MW-33
Chromium .- 76.94 39.8 4 717 MW-33
Cobalt .- 17.62 I\.6 4 7/7 MW-33
Copper - 59.84 46.4 4 7/7 MW-32
Manganese - 709.45 611 4 7/7 MW-33
Molybdenum - NA 1.14 19 7/7 MW-32
Nickel - 71.79 36.2 4 7n MW-32
Selenium - 0.48 5.24 B II 2/7 S8-29
Silver - \.06 0.599 4 1/7 MW-33
Vanadium - 66.16 75.1 4 7n MW-33
Zinc - 76.\ 7 71.7 4 7/7 MW-32
SW7060 (mg/kg) Arsenic - 9.31 8.21 19 7n MW-32
SW7421 (mg/kg) Lead .. 10.13 5.375 4 7/7 MW-33
I Alaska Cleanup Matrix (ACM) Level C; 18 AAC 78.315.
, The ACM Level C guideline for benzene, toluene, ethylbenzene, and xylenes (BTEX) combined is 50000 ~g/kg.
B - Sample concentration was less than or equal 10 the blank UTL.
NA - Not applicable.
S . Metal concentration reported waS obtained using the method of standard additions.
OU 6 ROD, Final
6-10
January 1997
-------
and subsurface soils; however, the maximum results for each were reported at levels near blank
concentrations. A total of eight VOCs were detected in the surface and subsurface soils. The same
suite of volatile organics was detected in both soil groups. The maximum VOC concentration detected
was xylene, at 209 J.lglkg in a sample from the pilot boring for MW-33.
6.3.2
Risk Evaluation
Based on the concentrations of contaminants detected during the RI, human health and
environmental risk assessments were perfonned to detennine if areas should be considered for remedial
action. All concentrations of contaminants, including all contaminants of concern, whether exceeding
MCLs 01' ACM guidelines or not, were included in the risk assessments. The general discussion of the
human h'~alth and ecological risk assessment procedures is presented in Section 2.3.2, and will not be
repeated since the procedures for each of the source areas within OU 6 were identical. Details on the
parameters used in the Health Risk Assessment are shown on Table 2.3-5.
Human Healtb Risk Assessment (lIRA)
Since LF03 is not currently used residentially, a current residential risk scenario was
not evaluated and only current visitor and trench worker scenarios were applied. Even though the future
land use at LF03 is restricted as specified in the Base Comprehensive Plan, the future residential risk
scenario was evaluated at LF03 to obtain the most conservative risk infonnation possible.
ELCRs and HIs were calculated to describe cancer and noncancer risks, respectively.
The ELCR is the additional chance that an individual exposed to site contamination will develop cancer
during hi:;lher lifetime. It is expressed as a probability such as 1.0E-06 (one in a million). The HI
estimates the likelihood that exposure to the contamination will cause some negative health effect. An
HI score ,iibove one indicates that some people exposed to the contamination may experience at least
one negative health effect.
The calculated risks at LF03 are based upon hypothetical exposure to soil and
groundwater. The shallow groundwater aquifer at LF03 is not presently used and will not be used in the
future for supplying potable or non-potable water. For carcinogenic soil risk, the calculated results for
the future resident (RME), construction worker, and visitor are listed. Only the future resident scenario
(RME) was used to calculate carcinogenic groundwater risk. Table 6.3-4 summarizes the calculated
carcinogenic and noncarcinogenic human health risks calculated for LF03.
Cancer risk using the residential RME scenario for groundwater at LF03 exceeds
I.OE-04. The low levels of 1,2-dichloroethane and beryllium present at the site (both below MCLs)
drive this risk. Noncarcinogenic risk above 1.0 was also identified for groundwater at LF03. This risk
is driven Iby the occurrences of beryllium and antimony in the groundwater. No soil risk was identified.
Ecological Risk Assessment (ERA)
The ERA was performed to determine if the reported concentrations of chemicals or
calculated exposures to plants and wildlife at OU 6 are likely to produce adverse effects. Ecological
effects wc:re evaluated quantitatively by calculating Ecological Quotients (EQs). The ERA focused on
evaluating potential impacts of the contamination on selec'ted indicator species: the moose, masked
shrew, mc:adow vole, black-capped chickadee, merlin, and peregrine falcon. The general discussion of
the ecological risk assessment procedures is presented in Section 2.3.2 and will not be repeated since
the procedures for each of the source areas within OU 6 were identical.
January 1997
6-11
OU 6 ROD, Final
'C
-------
Table 6.3-4
Summary of Human Healtb Risks at LF03
Elmendorf AFB, AI(
Surface Soil (
-------
The calculated ecological quotient (EQ) of 1.0 was exceeded for the black capped
chickade:e, meadow vole and shrew due to an elevated selenium con~entration. The highest selenium
EQ was 'equal to 180 for the masked shrew. EQs were calculated based on surface soil contaminant
concentrations. None of the calculated EQs exceeded 1.0 for the moose, peregrine falcon, or merlin at
LF03. It is highly likely that the data used to calculate the EQs for selenium at LF03 are not
representative of landfill contamination since: (1) the results were collected at locations cross-gradient
to and away from the landfill; and (2) there is substantial uncertainty associated with the selenium
results based upon the method used and the low levels detected. .
Uncertainties Associated with the Risk Assessment
The major assumption and uncertainty factors for the OU 6 human health and'
ecological risk assessments are presented in Section 2.3.2.
6.3.3
Conclusions
The following subsections provide a discussion of the detennination ofCOCs for LF03,
the locati,on and extent of contamination by any COCs in excess of preliminary remediation goals, and a
summar}' statement about the risk to public health, welfare, or the environment if action is not taken at
LF03.
Contaminants of Concern
Constituents exceeding preliminary remediation goals (MCLs for groundwater or ACM
guidelines for soils) were identified in the Proposed Plan. COCs for OU 6 were developed from the
results of the risk assessment and by considering preliminary remediation goals. Each constituent
having an individual contribution greater than I .OE-06 carcinogenic (RME) risk, or an HI greater than
0.1 when the cumulative HI for the site is greater than 1.0, was considered as a COCo In addition, any
constituent exceeding preliminary remediation goals (MCLs) for groundwater or ACM guidelines for
soil was nlso considered as a COC.
No COCs were identified for LF03, based upon the above criteria. As noted in Table
6.3-4, thr,ee constituents contributed to excess risk in the groundwater at LF03. Antimony was found
only at elevated concentrations in samples with high turbidity and therefore was attributed to dissolution
of contaminants adsorbed on soil particles in the turbid samples. Beryllium and 1,2-dichloroethane
were not identified as COCs because their concentrations were less than MCLs and the cancer risk
associated with these constituents was within the acceptable risk range.
The Proposed Plan listed antimony and cadmium as exceeding MCLs in the
groundwater at LF03. As previously discussed, antimony was not identified as a COC because of high
turbity in the samples. Cadmium was not identified as a COC because the risk assessment indicated no
significant risk, and the MCL was only marginally exceeded in a single sample from one well. The RI
also identified chromium, nickel, and arsenic as exceeding MCLs. These metals also were not
identified as COCs because the risk assessment identified no significant risk and the MCLs were only
marginally exceeded. Additionally, all metals in groundwater were detennined to be comparable to
backgroulrtd concentrations.
Summary
No COCs were identified for Source LF03; therefore, there is no risk of imminent or
substantinl endangennent to public health, welfare, or the environment at this site. As a consequence,
no further response action is required, .
January 1997
6-13
OU 6 ROD, Final
-------
Remedial Action Objectives. Alternatives. and Comparative Analysis for LF03
The following subsections discuss the remedial action objectives for LF03, and present
a description of the various alternatives which were evaluated to achieve those remedial objectives. The
results of the detailed comparison made between those alternatives are also presented.
6.4
6.4.1
Remedial Action Objectives
Remedial action objectives (RAO) are developed based on COCs, potential exposure
routes and receptors, and remediation goals. As discussed in Section 6.3.3, the groundwater and soils in
LF03 have no COCs; thus, RAOs were not developed for LF03 groundwater or soils.
Groundwater Alternatives
Groundwater alternatives are developed to meet RAOs. As discussed in
Sections 6.3.3 and 6.4.1, the groundwater at LF03 does not have any COCs or RAOs; therefore.
alternatives were not developed for the LF03 groundwater. Consequently, a comparative analysis of
groundwater alternatives was not conducted.
6.4.2
Soil Alternatives
. Soil alternatives are developed to meet RAOs. As discussed in Sections 6.3.3 and 6.4.1,
the soils at LF03 do not have any COCs or RAOs; therefore, alternatives were not developed for the
LF03 soils. Consequently. a comparative analysis of soil alternatives was not conducted. ADEC has
indicated that the existing cover at LF03 is compliant with state standards for landfill closure (18 AAC
60.390) concerning applying a final cover to landfilled wastes.
6.4.3
6.S
Selected Remedy for LF03
Access to groundwater and soil at LF03 will be institutionally controlled. LF03 is
currently designated as a "restricted use area" in the Base Comprehensive Plan. This designation
provides for recreational use of the parcel (cross country skiing. etc.) and for construction of unmanned
facilities such as a parking lot. storage building, or taxiway, but prohibits the construction of any sort of
manned facility such as an office building or a residence. Drilling into the shallow aquifer is also
restricted by the Base Comprehensive Plan. As a former landfill, LF03 will maintain this designation
indefinitely. Therefore, the selected remedy for LF03 is as follows:
Groundwater at LF03:
.
No further action is required for the groundwater at LF"03.
Soil at LF03:
.
No further action is required for the soil at LF03.
.
No further action will be required as a means of closing the LF03 landfill.
The State of Alaska concurs with the USAF and the USEP A in the selection of no
further action for LF03. Based on comments during the public comment period, the public has no
preference.
OU 6 ROD, Final
6-14
January 1997
.'"
-------
6.5.1
Statutory Determinations
There are no risks to human health or the environment, and no ARARs associated with
LF03. Access to groundwater and soil at LF03 will be institutionally controlled. LF03 is currently
designated as a "restricted use area" in the Base Comprehensive Plan. This designation provides for
recreational use of the parcel (cross country skiing, etc.) and for construction of unmanned facilities
such as a parking lot, storage building, or taxiway, but prohibits the construction of any sort of manned
facility such as an office building or a residence. Drilling into the shallow aquifer is also restricted by
the Base Comprehensive Plan. As a former landfill, LF03 will maintain this designation indefinitely.
Therefor(:, no further action is required.
6.5.2
Documentation of Significant Changes
The Proposed Plan lists groundwater contaminants with concentrations in excess of
cleanup guidelines. This list differs from the COCs established in Section 6.3.3, because identification
of COCs includes evaluation of risk and sample quality along with comparison to cleanup levels. No
COCs were identified at LF03. This was a logical outgrowth of the Proposed Plan and did not affect the
choice of alternatives at LF03. Therefore, the selected remedy was the preferred alternative presented
in the Proposed Plan (Table 7 of the Proposed Plan).
January 19'97
6-15
OU 6 ROD, Final
-------
[This page intentionally left blank.]
-------
SECTION SEVEN
-------
7.0
7.2
7.3
7.4
7.5
7.1-1
TABLE OF CONTENTS
Page
S()URCE S073 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
7.1
Site Oescription ...................... . . . . . . . . . . . . . '. . . . . . . . . . . . . . . . . . . 7-1
7.1.1 Land Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
7.1.2 Hydrogeology and Groundwater Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
7.2.1 Identification of Activities Leading to the Current Contamination
at S073 .................................................. . . . . 7-3
Site Contamination, Risks, and Areas Requiring Response Actions. . . . . . . . . . . . . 7-3
7.3.1 Nature and Extent of Contamination ............................... 7-3
7.3.2 Risk Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10
7.3.3 Conclusions. .... ........ . .... . ..... . .. . . ..... ..... . . . . ... . .. . .7-12
Remedial Action Objectives, Alternatives, and Comparative Analysis for S073 ...7-12
7.4.1 Remedial Action Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-13
7.4.2 Groundwater Alternatives.. ... .. . . . .. . . . . . . ... . . ..... . . . . . . . . . . . . 7-13
7.4.3 Soil Alternatives.... . .. . . ... . . .. ... ... . .. . . . . . .. . . . . . .. . . . . . . . . 7-13
Selected Remedy for SD73 ............................................. 7-13
7.5.1 Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-13
7.5.2 Documentation of Significant Changes. . .. . .. . . . . . . .. . . . . . . . .. . .. . .7-13
LIST OF FIGURES
Page
Location Map for Source Area S073 ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
7.3-1
LIST OF TABLES
Page
Summary of Groundwater Analytical Results for Source S073,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
7.3-2
Summary of Surface Soil Analytical Results for Source S073,
Elmendorf AFB, AK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6
-------
7.3-3
7.3-4
LIST OF TABLES (CONTINUED)
Page
Summary of Subsurface Soil Analytical Results for Source SD73,
Elmendorf AFB, AK . ... . . . . . . .. .. .. .., . .. . .... .. . . . . . . .. . . . . . . . . . . . . .. . . . . . . 7-8
Summary of Human Health Risks at Source SD73, Elmendorf AFB, AK
Elmendorf AFB, AK .. . . . . . .. .. . . ... .. . ... ..., .. . . . . . . . . . . . . . . .. . . . . . . . . . . .. 7-11
11
-------
Section 7.0
SOURCE SD73
The following subsections describe the physical description, land use, groundwater use,
and hydrogeology of S073. The identification of activities which led to the current contamination at
S073 is allso included. The discussion of the regulatory and enforcement history of S073, the role of the
response 2lction at S073, and community participation in the response action ~re included in the general
IOU 6 discussion in Section 1.0. The detailed discussion of the hydrogeology at S073 was combined
with the d1escription of the hydrogeology at LF02 and LF03, and is presented in Section 5.1.2. These
discussions were combined because of the close proximity between Sources LF02, LF03 and S073 on
the glacial outwash plain.
'7.1
Site Description
Source 5073 (Figure 7.1-1) is located in the glacial outwash plain to the south of Ship
Creek. SD73 is located approximately 2400 feet northwest of Source LF03. The topographic elevation
at this soulrce area is approximately 205 feet above mean sea level, and the terrain slopes regionally at
approxima.tely 100 feet per mile to the west. The area defined as S073 encompasses a surface disposal
area wher~: chemicals from a fonner United States Geological Survey (USGS) rock testing and film
processing. laboratory were reportedly discharged onto the ground directly or via open drains. Based
upon the architectural style of the buildings at the site, it appears to have been constructed in the late
1 940s or early 1950s. The entire facility was occupied by the National Oceanic and Atmospheric
Administration (NOAA) around 1977.
This source area was defined as a result of an Environmental Baseline Assessment
(EBA) conducted during the summer of 1993 at the facility. Following that study, the surface disposal
a.rea surrounding the former USGS rock laboratory was designated as Source S073 and was added
to au 6.
7.1.1
Land Use
Land use for S073 is light industrial. As mentioned above, the area is included in a
facility formerly operated by the USGS and NOAA. Light maintenance shops and a former fueling
station, as well as several storage sheds, are located at the facility in the vicinity of S073. There are no
known historic buildings, archeological sites, wetlands, floodplains, or rare or endangered species at
S073. The: land use designation may be changed to residential in the future. .
7.1.2
Hydrogeology and Groundwater Use
The discussions of the geologic and hydrogeologic settings for Sources LF03, LF02, and
S073 have: been combined because of their similar hydrogeologic regimes and close proximity on the
glacial outwash plain. The general site map for S073 is presented as Figure 7.1-1. The hydrogeologic
conceptual model for S073, showing the main hydrostratigraphic units in the area, is included with that
for LF02, and presented as Figure 5.1-3. For a more general description of Elmendorf AFB geology and
hydrogeology, see Section 1.0 of this document or the OU 6 Remedial InvestigationlFeasibility Study
(USAF, 1 996b).
The groundwater in the shallow aquifer at S073 is not used for any purpose on base. Its
future use, even if the aquifer was uncontaminated, is generally limited because of the higher yield of the
deeper confined aquifer below the Bootlegger Cove Clay. The fine-grained nature of the aquifer material
January 1997
7-1
OU 6 ROO, Final
-------
o
C
0\
::.a
o
5'
'TI
5.
!!.
-.I
.
IV
....
~
c
~
-
\Q
\Q
-.I
NOAA
Research
Station
J"
A'2
D
North
- ~50URCE 5D73
I
I
" I
I
SCALE
0 50 100 ~
I . in
..,
"
Feel 0
'"
I / /j
I (
I I
I I
" I
: I
I
I
I
I
I
--___--_0
ELMENDORF AFB
_u- Source Area Boundary
,
(
Figure 7.1-1. Location Map for Source Area SD73
<#
---
-------
at this source area, providing minimal groundwater yield, would make the shallow aquifer at S073
unsuitable as a drinking water supply aquifer.
'7.2
Site History and Enforcement Activities
The following section identifies the activities which lead to the current contamination at
S073. The regulatory and enforcement history for S073 is included in the general discussion presented
for OU 6 in Section 1.0, as are the discussions of the role of the response action and the community
participation in the response.
i'.2.1
Identification of Activities Leading to the Current Contamination at SD73
The primary contamination seen at S073 is associated with the soil, which is
contaminal:ed with metals and semi-volatile organic compounds. As with most of the OU 6 source areas,
the principal source of contamination at S073 is previous waste management activities conducted at this
location. Laboratory wastes, either passed through open drains onto the ground surface, or dumped in
the vicinit)' of the laboratory facility, have allowed metals and other laboratory wastes to leach into the
soil, and potentially impact the groundwater at this source area. A localized dumping area immediately
behind the testing laboratory, referred to as a "disposal pit," was also investigated as part of the RI. The
contaminants identified in the soils are primarily located in the upper few feet, consistent with the
disposal of small quantities ofliquid or solid wastes over a fairly long period of time.
Significant contamination at S073 is limited to the soil only, as the low levels of ,
rc~latively immobile constituents have not substantially impacted groundwater. In addition, upgradient
groundwatc~r results demonstrate the same low level organic compounds as were detected at the
downgradic~nt locations. No other sources in the vicinity of S073 have been identified. Also, no
contaminant "smear zone" was detected. A schematic of the potential migration and exposure pathways
fi)r constiwlents from Sources S073 and LF02 through the soil and potentially into the groundwater is
presented illl Section 5.2 as Figure 5.2-1. .
Prior to the RI conducted at S073 in 1994, S073 had been addressed only under one
, g,eneral study, the NOAA Environmental Baseline Assessment (EBA) Work Plan (Radian, 1993) and
subsequent EBA Report (Radian, 1993). Rock testing and film processing activities at S073 were
discontinue:d prior to 1977 when NOAA occupied the facility. No other sources were identified requiring
action at this source area.
7.3
Site Contamination. Risks. and Areas Requiring Response Actions
This section identifies the areas which were investigated, and those that require remedial
al:tion. Tht:se areas were chosen based on the risk that contaminants pose to human health and the
environment. The basis of this analysis is the data collected during the Remedial Investigation (RI)
which idenltified the nature and extent of contamination at S073.
7..3.1
Nature and Extent of Contamination
Ouring the RI, samples of soil and groundwater were collected and analyzed for organic
and inorganic constituents. Both organic and inorganic contaminants were detected in the 'soil and
gll'Oundwatt:r at S073. These contaminants include low levels of volatile organic compounds, including
solvents, metals, and SVOCs. The contamination present at S073 is associated with contaminant
transport in the vadose zone, dissolved aqueous transport, and volatilization. These transport
mechanisms are pictorially represented for S073 in Figure 5.2-1.
January 1997
7-3
OU 6 ROO~ Final
'<
-------
Tables 7.3-1 through 7.3-3 list the frequency of occurrence and maximum concentrations
of all constituents which were detected during the Rl in groundwater and soil. The tables do not include
results below the detection limit. The MCLs for groundwater and the ACM guidelines for soil are also
listed on the tables for all constituents. Results are separated between "indicator parameters" and
"contaminant parameters." Indicator parameters primarily include metals classified as nutrients, and
non-speciated fuel constituents such as UDRO which are unsuitable for use in a risk assessment. A
detailed discussion of the determination of the COCs for S073 is presented in Section 7.3.3.
Groundwater Contamination at SD73
The groundwater constituents detected at S073 include low levels of several HVOCs as
well as BTEX constituents. Low levels of metals were also detected (Table 7.3-1). Among all of the
VOCs, the highest concentration detected was for acetone, at 12.8 J.lg/L. This concentration was flagged
as being near the level detected in blank samples, as were many of the VOC maxima. Two SVOCs were
detected, also at low concentrations, with the maximum occurring for dimethylphthalate at 8.18 J.lg/L in a
sample from well N-3. Like at LF02 and LF03, organic groundwater contaminant concentrations were
substantially lower than those previously discussed for source areas WP 14, LF04, and SO 15.
Four metals, barium, beryllium, manganese, and zinc, were detected at low levels in the
groundwater at SD73 C~able 7.3-1). As at other OU 6 source areas, a statistical comparison of these
metals concentrations was made to available background metals concentrations. Based upon this
evaluation, all metals evaluated in the groundwater at S073 were determined to be below background
concentrations. The summary statistics for the USGS data, including the upper confidence limit
concentrations used for these comparisons, are presented in Table 2.3-4.
Soil Contamination at SD73
Soil data from S073 were evaluated based upon surface and subsurface contaminant
occurrences. Surface soils include all soils collected from depths shallower than 3 feet bgs. Subsurface
soils are those collected from below 3 feet. Tables 7.3-2 and 7.3-3 list the sample depths, maximum
concentrations, locations, and guidelines associated with the ACM for non-UST soil for all contaminant
parameters in the surface and subsurface soil samples at S073. Results below the detection limits are not
included in the analytical summary tables.
Contamination in the surface and subsurface soils at S073 was similar to that found at
LF03. The contaminants present include low levels of BTEX constituents, metals, VOCs, and SVOCs.
Metals were frequently detected in the surface and surface soils at S073. Metals occurrences, via
comparison to background results (Table 7.3-2 and 7.3-3) were determined to be at or near background
concentrations. Numerous SVOCs were detected in both surface and subsurface soils; however, each
constituent was detected rather infrequently. The maximum SVOC detection was
53.7 mglkg for bis(2-ethylhexyl)phthalate in a surface sample from A2-HA-3-01. A total of nine VOCs
were detected in the subsurface soils and four in the surface soils. BTEX constituents were only detected
in the subsurface soils. The maximum VOC concentration detected in the soils was xylene, at
1320 J.tglkg in a sample from soil boring SB-37.
OU 6 ROD, Final
7-4
January 1997
-------
Table 7.3-1
Summary of Groundwater Analytical Results for Source ~D73
Elmendorf AFD, AK
Frequency of Location of
Met bod Analyte MCL' Mnimum Detections Maximum
(unll") Result Total Hits!
Total Samples Resnl"
Indicator Parameters
SW6010. Total Aluminum - 0.239 6/6 N-3
(mg/L) Calcium - 24 6/6 MW-42
Iron - 0.237 6/6 N-3
Magnesium - 5.11 6/6 MW-42
Sodium - 2.~ 6/6 MW-42
Contaminut Parameters
SW8260 (J.1IVL) Acetone - 12.8B 6/6 MW-40
Benzenc 5 0.36 B 1/6 MW-42
Chlorofonn 100 0.22 3/6 MW-42
Chloromethane -- 2.33 B 6/6 N-3
1.2-Dichloroethane 5 2.2 2/62 N-3
Ethylbenzene 700 0.36 2/6 MW-42
2-Hcxanone - 1.6 2/6 MW-40
Methylene chloride S 1.22 B 6/6 N-3
Toluene 1000 0.63 6/6 MW-42
m & p-Xylene - 0.35 2/6 MW-42
a-Xylene - 0.12 B 1/6 MW-42
SW8270 (J.1Iv'l) Dimethylphthalate - 8.18 2/6 N-3
b is(2 -Ethy I hexyl )phthal ate 6 4.45 B 1/6 MW-40
SW6010. Total Barium 2 0.00714 B 6/6 MW-42
(mg/L) Beryllium 0.004 0.00169 B 4/6 MW-40
Manganese - 0.0138 5/6 MW-42
Zinc -- 0.00779 B 3/6 N-)
I Maximum contaminant level (MCL); 40 CFR t 141.61 for Federal MCLs. and 18 MC 80.070 for State MCLs. Federal and State MCLs
are identical for the listed constituents.
2 Frequency ";hits"calculation does not include one or more results removed from the data set because they did not meet QAlQC criteria.
Total sample count includes all samples analyzed for the indicated parameter.
B - Sample concentration was less than or equal to the blank UTL.
January 1997
7.5
OU 6 ROD, Final
-------
Table 7.3-2
Summary of Surface Soil Analytical Results for Source SD73
Elmendorf AFB, AI(
Bukground Deptb of Frequency of Location of
Metbod ACM Upper Mnimum Detection
(UDils) Analyte Guideline I Tolerance Result Malimum Total Hits! Mnimum
Umit Resulls (0) Total Samples Result
Indicator Parameters
SW9045 (pH units) pH - .. 6.95 1.5 III SS-080
D2216 (percen!) Percent moisture - - 32.4 3 19/19 Al-SS 18
SW8015MP (J.ag/kg) Ethylbenzene -- 2 11.3 P 3 1/4 Al-SSI5
-
Toluene .. 2 31.3 8 3 4/4 Al-HA-I.OI
-
Xylene (total) .. 2 91.1 3 2/4 Al-SS\7
-
SW6010 (mg/kg) Aluminum -. 31183.96 3\000 I 19/\9 SS-082
Calcium - 8013.23 8320 I 19119 SS-084
Iron -- 43192.35 35100 1.5 19/19 SS-081
Magn!=sium -- 10904.10 9680 2 19/19 MW-40
Potassium .. 845.75 1620 3 19/19 Al-HA-3-01
Sodium - 427.05 259 3 19/19 Al-HA-3-01.
Contaminant Parameters
SW8240 (Ilg/kg) Acetone -- .. 12.68 1.5 9/19 SS-079
2-8utanone(MEK) -- - 44.68 3 11119 Al-SSI7
Chloroform -- -- 30.\ I.S 7/19 SS-081
Methylene chloride -- - 31.5 3 11/19 Al-HA-3-01
SW8270 (mg/kg) Acenapthylene - - 0.0222 3 1119 Al-SSI6
Anthracene -- - 0.0719 3 1/19 Al-SSI6
Benzo(a)anthracene -- - 0.216 3 2/19 Al.SSI6
Benzo( a)pyrene - - 0.327 3 2/19 Al-SS 16
Benzo(b )f1uoranthene .. .- 0.945 F 3 4/19 Al-SSI6
Benzo(g,h,i)perylene .. n 0.0821 3 1/19 Al-S516
Benzo(k)Ouoranthene - -- 0.945 F 3 3119 Al-SSI6
Benzyl alcohol - -- 0.188 1 1119 SS-083
bis(2-Ethylhexyl) .. - 53.7 3 6/19 Al-HA-3-01
phthalate
Butylbenzylphthalate n -- 0.0488 3 2/19 Al-SS 16
Chrysene -- -- 0.595 J 6119 Al-SSI6
Dibenz( a,h)anthracene - - 0.047 3 1/19 A2-SS 16
Di-n-butylphthalate .. - 0.325 3 2/19 Al-SS 15
Di-n-octylphthalate -- -- 0.0784 3 2/19 Al-S515
Fluoranthene -- -- 0.762 1.5 4/19 S5-081
Indeno( 1,2,3-cd)pyrene -- -- 0.102 3 1119 Al-SSI6
2.Methylnaphthalene .. - 25.7 2 4/19 SB-37
Naphthalene .. -- 0.33 3 2/19 Al-SSI7
4-Nitroaniline - -- 0.13 3 1/\9 Al.SSI5
Pentachlorophenol -- - 0.245 3 5/19 Al.HA-2.01
Phenanthrene -- - 1.3 2 6/19 SB-37
Pvrene -- -. 0.508 I.S 5/19 SS-081
OU 6 ROD, Final
7-6
January 1997
"<
-------
Table 7.3-2
(Continued)
Background Depth or Frequency or Location or
Metbod ACM Upper Maximum Detec:don
(unilS) Analyte Guideline I Tolerance Resalt M8Ilmum Total HIUI Maximum
Limit Resulu (ft) Total Samples Resalt
SW60IO (mglkg) Antimony - NA 280 3 7/19 A2-HA-3-o1
Barium - 196.45 516 3 19/19 A2-HA-3-o1
Beryllium -- 0.76 0.73 2 19/19 MW-43
Cadmium - 2.68 2.34 3 4/19 A2-HA-3-01
Chromium - 48.44 40.6 3 19119 A2.HA-1-o1
Cobalt - 19.52 14.2 2 19/19 MW-43
Copper - 31.67 177 3 19/19 A2-SSI6
Manganese -- 929.98 743 2 19/19 MW-43
Molybdenum - NA 2.53 3 15/19 A2-HA-3-o1
Nickel - 50.68 35.2 3 19/19 A2-HA-1-01
Selenium -- 0.54 16.5 2 11/19 SB-37
Silver - 1.68 107 3 7/19 A2-HA-3-o1
Vanadium - 10\.64 87.2 l.S 19119 SS-081
Zinc - 90.01 898 3 19/19 A2-SSI7
SW7060 (mglkg) Arsenic - 13.27 26 3 19/19 A2-HA.3-0 I
SW724 1 (mglkg) Lead -- 10.69 339 3 19/19 A2-SSI6
SW'J'471 (mglkg) Mercury - 0.20 0.537 3 17/19 A2.SS 16
, Alaska CleanulP Matrix (ACM) Level C; 18 AAC 78.3 I 5.
2 The ACM Lev
-------
Table 7.3-3
Summary of Subsurface Soil Analytical Results for Source SD73
Elmendorf AFB, AK
BacqroDud Depth of Frequcacy of' LOCltion of
Method ACM Upper Masimam DetKtion
(uaib) Anllyte Guideline I Tolenace Result Maximum Total Bib! Ma:limum
U.it Resulb (R) Total Simples Result
ladicator PUlmeten
SW9045 (pH units) pH -- - 7.37 14 III MW-40
D2216 (percent) Percent moisture - - 25.3 4 39/39 SB-37
SW6010 (mg/kg) Aluminum - 18116.77 22000 4 21121 SB-37
Calcium - 10264.39 9650 26 .21121 SB-39
Iron - 38483.64 31000 4 21121 SB-37
Magnesium - 14784.34 12000 30 21121 S8-38
Potassium - 1114.35 1260 4 21121 MW-40
Sodium - 365.59 185 10 21121 SB-38
Contamiaaat Plnmctcn
SW8240 ~g/kg) Acetone -- - 81.3 B 4 14121 SB-37
2-Butanone(MEK) - - 20.9 B 4.5 15121 A2-HA-1-02
Chloroform - -- 31.7 6 8121 5B-41
Elhylbcnzene - 2 - 127 4 1121 5B-37
Melhylene chloride - - 12 4.5 11121 A2-HA-1-02
Toluene _2 - 130 4 2121 SB-37
Tribromomelhane - - 28.1 6 2121 SB-41 I
(Bromoform)
m & p-Xylene _2 - 1320 4 1121 SB-37
o-Xylene _2 -- 994 4 1121 5B-37
SW8270 (J,lglkg) Benzo(a)pyrene - - 0.274 4 1121 MW-40
Benzo(b )nuoranlhene - - 0.444 F 4 1121 MW-40
Benzo(k) noranthene - -- 0.444 F 4 1121 MW-40
Chrysene -- -- 0.228 4 1/21 MW-40
Di-n-butylphlhalate -- -- 0.32 4.5 1/21 A2-HA-3-02
bis(2-Elhylhexyl) .. - 15.7 4.5 2121 A2-HA-3-02
phlhalate
Fluoranlhene -- -- 0.301 4 1121 MW -40
2-Melhylnaphthalene -- - 0.0314 26 1121 SB-39
Phenanlhrene -- - 0.388 4 1121 SB-37
Pyrene .. -- 0.271 4 2128 MW -40
SW60 1 0 (mglkg) Antimony -- NA 10.9 28 10121 MW-43
Barium -- 95.93 125 4 21121 5B-37
Beryllium - 0.64 0.644 8 21121 SB-41
Chromium -- 76.94 42.2 22 21121 MW-40
Cobalt -- 17.62 11.8 12 21/21 5B-39
Copper - 59.84 30.7 12 21121 5B-39
Manganese -- 709.45 623 10 21121 SB-43
Molybdenum - NA 1.63 4 17121 MW-40
Nickel - 71.79 39 12 21121 5B-39
5W6010 (mg/kg) Selenium -- 0.48 18.6 30 21121 5B-38
Silvcr -- 1.06 3.25 4.5 9121 A2-HA-3-02
Vanadium -- 66.16 71.9 26 21121 SB-39
OU 6 ROD. Final
7-8
January 1997
-------
Table 7.3-3
(Continued)
Background Deptb of Frequency of Location of
Method ACM Upper Muimum Detection
(units) AnaJ)'te Guideline I Tolerance Result Malimum Total Hilsl Mllimum
Limit ResuJts (ft) Total Samples Raull
SW6010 (mglkg) Zinc - 76.17 98.7 4 21121 5B-37
(continued)
SW7060 (mglkg) Arsenic - 9.31 70.4 4.5 21121 Al-HA-3-02
SW7421 (mg/kg) lead - 10.13 29.8 4 21121 5B-37
SW7471 (mglkg) Mercury - 0.21 0.87 4 14121 5B-37
, Alaska Cleanup Mabix (ACM) level C; 18 AAC 78.315.
1 The: ACM Level C guideline for benzene, toluene, ethylbenzene, and xylenes (BTEX) combined is 50000 ~glkg.
B - Sample C
-------
Risk Evaluation
Based on the concentrations of contaminants detected during the RI, human health and
environmental risk assessments were performed to determine if areas should be considered for remedial
action. All concentrations of contaminants, including all contaminants of concern, whether exceeding
MCLs or ACM guidelines or not, were included in the risk assessments. The general discussion of the
human health and ecological risk assessment procedures is presented in Section 2.3.2, and will not be
repeated since the procedures for each of the source areas within OU 6 were identical. Oetails on the
parameters used in the Health Risk Assessment are shown on Table 2.3-5.
7.3.2
Human Healtb Risk Assessment (BRA)
Since S073 is not currently used residentially, a current residential risk scenario was not
evaluated and only current visitor and trench worker scenarios were applied. This area may be used
residentially in the future~ therefore, the future residential risk scenario was evaluated at S073 to obtain
the most conservative risk information possible.
ELCRs and H1s were calculated to describe cancer and noncancer risks, respectively.
The ELCR is the additional chance that an individual exposed to site contamination will develop cancer
during hislher lifetime. It is expressed as a probability such as 1.0E-06 (one in a million). The H1
estimates the likelihood that exposure to the contamination will cause some negative health effect. An
HI score above one indicates that some people exposed to the contamination may experience at least one
negative health effect.
The calculated risks at S073 are based upon hypothetical exposure to soil and
groundwater. The shallow groundwater aquifer at S073 is not presently used, and will not be used in the
future for supplying potable or non-potable water. For carcinogenic soil risk, the calculated results for
the future resident (RME), construction worker, and visitor are listed. Only the futu.re resident scenario
(RME) was used to calculate carcinogenic groundwater risk. Table 7.3-4 summarizes the calculated
carcinogenic and noncarcinogenic human health risks calculated for S073.
The residential RME cancer risk for groundwater at S073 exceeds I.OE-06. This risk is
driven exclusively by I ,2-dichloroethane, which was detected at a maximum concentration well below
MCLs. Noncarcinogenic risk was not identified in the groundwater. In soils, the residential RME cancer
risk exceeded I.OE-OS, and the visitor scenario exceeded I.OE-06. This risk is driven entirely by arsenic,
which occurs at background concentrations. Noncarcinogenic risk for soils was also identified in the
RME scenario above 1.0 for arsenic and manganese.
Ecological Risk Assessment (ERA)
The ERA was performed to determine if the reported concentrations of chemicals or
calculated exposures to plants and wildlife at OU 6 are likely to produce adverse effects. Ecological
effects were evaluated quantitatively by calCulating Ecological Quotients (EQs). The ERA focused on
evaluating potential impacts of the contamination on selected indicator species: the moose, masked
shrew, meadow vole, black-capped chickadee, merlin, and peregrine falcon. The general discussion of
the ecological risk assessment procedures is presented in Section 2.3.2 and will not be repeated 'since the
procedures for each of the source areas within OU 6 were identical.
Both metals and SVOC concentrations were sufficient in soils at S073 to cause the EQs
for small animals to exceed 1.0. EQs exceeded 1.0 for the black capped chickadee and meadow vole due
7-10
January 1997
au 6 ROO, Final
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Table 7.3-4
Summary of Human Healtb Risks at SD73
Elmendorf AFB, AK
Surface Soil (<3 feet) Subsurface Soil
Risk Chemical(s) Driving
Residential Visitor Trench Risk
Scenario. Scenariob Worker Scenario'
i Soil Risk d
Carcinogc:nic 2.4E-05 1.4E-06
NA - Not applicable.
NR - Signifi':ant risk not identified.
January 1997
7-11
au 6 ROD, Final
-------
to elevated lead, selenium, and zinc concentrations. Elevated lead also caused the EQ for the masked
shrew to exceed 1.0. The highest calculated EQ was for lead for the black capped chickadee (2200),
followed by an EQ of 720 for barium, also'for the black capped chickadee. In addition,
benzo(a)anthracene concentrations caused exceedances for the black capped chickadee, and
benzo(a)anthracene and bis(2-ethylhexyl)phthalate caused exceedances for the shrew. EQs were
calculated based on surface soil contaminant concentrations. The highest organic EQ was 4.9, for
bis(2-ethylhexyl)phthalate in the black capped chickadee. None of the calculated EQs exceeded 1.0 for
the moose, peregrine falcon, or merlin at S073. From an ecological risk point of view, it is n9t believed
that wildlife in this area will be significantly affected since the area is scheduled to be converted into a
housing/community development. While EQs did exceed 1.0 for several constituents and indicator
species, the risk estimates are considered to be very conservative based on the planned land use for this
source area.
Uncertainties Associated with the Risk Assessment
The major assumptions and uncertainty factors for the au 6 human health and
ecological risk assessments are presented in Section 2.3.2.
Conclusions
The following subsections provide a discussion of the determination ofCOCs for S073,
the location and extent of contamination by any COCs in excess of preliminary remediation goals, and a
summary statement about the risk to public health, welfare, or the environment if action is not taken at
S073.
7.3.3
Contaminants of Concern 0
No constituents exceeding preliminary remediation goals (MCLs for groundwater or
ACM guidelines for soils) were identified in the Proposed Plan. COCs for au 6 were developed from
the results of the risk assessment and by considering prelfminary remediation goals. Each constituent
having an individual contribution of greater than I.OE-06 carcinogenic (RME) risk, or an ill greater than
0.1 when the cumulative HI for the site is greater than 1.0, was considered as a cae. In addition, any
constituent exceeding preliminary remediation goals (MCLs for groundwater or ACM guidelines for
soil) was also considered as a COC.
No COCs were identified for S073 based upon the above criteria. The carcinogenic risk
for groundwater was exceeded only by 1,2-dichloroethane. The concentrations of this constituent did not
exceed MCLs; therefore, it was not included as a COC. Metals concentrations in the groundwater were
below MCLs and were comparable to background concentrations. Arsenic and manganese in the soils
were not considered COCs because the concentrations detected were comparable to background levels.
Summary
No COCs were identified for Source 8073; therefore, there is no risk of imminent or
substantial endangerment to public health, welfare, or the environment at this site. As a consequence, n6
further response action is required.
7.4
Remedial Action Objectives. Alternatives. and Comparative Analysis for SD73
The following subsections discuss the remedial action objectives for S073, and present a
description of the various alternatives which were evaluated to achieve those remedial objectives. The
results of the detailed comparison made betWeen those alternatives are also presented.
au 6 ROD, Final
7-12
January 1997
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., .4.1
Remedial Action ObJectives
Remedial action objectives (RAO) are developed based on COCs, potential exposure
routes and receptors, and remediation goals. As discussed in Section 7.3.3, the groundwater and soils in
S073 hav€: no COCs; thus, RAOs were not developed for S073 groundwater or soils.
7.4.2
Groundwater Alternatives
Groundwater alternatives are developed to meet RAOs. As discussed in Sections 7.3.3
and 7.4.1, the groundwater at S073 does not have any COCs or RAOs; therefore, alternatives were not
developed for the S073 groundwater. Consequently, a comparative analysis of groundwater alternatives
was not conducted.
7.4.3
Soil Alternatives
Soil alternatives are developed to meet RAOs. As discussed in Sections 7.3.3 and 7.4.1,
the soil at :5073 does not have any COCs or RAOs; therefore, alternatives were not developed for the
S073 soils. Consequently, a comparative analysis of soil alternatives was not conducted.
".5
Selected Remedy for SD73
The selected remedy for S073 is as follows:
Groundwater at SD73:
.
No further action is required for the groundwater at S073.
Soil at SD73:
.
No further action is required for the soil at S073.
The State of Alaska concurs with the USAF and with the USEPA in the selection of no further action for
S073. Ba!;ed on comments received during the public comment period, the public has no preference.
7.5.1
Statutory Determinations
There are no risks to human health and the environment and no ARARs associated with
S073. No further action is required.
Documentation of Significant Changes
The selected remedy was the preferred alternative presented in the Proposed Plan
(Table 7 oj[ the Proposed Plan).
7.5.2
January 1997
7-13
OU 6 ROD, Final
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SECTION EIGHT
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Section 8.0
REFERENCES
Alaska D~~partment of Environmental Conservation (ADEC). Resource Conservation and Recovety Act
LE~CRA) Facili~ Assessment Report: Preliminaty Review and Visual Site Inspection. 1988.
Black and Veatch. Installation Restoration Proiram Staie 3 Remedial Investiiation/Feasibili~ Study
.EJmendorf Air Force Base. Alaska. 1990.
ENSR. .EJmendorf Air Force Base. SERA Phase I B Site Assessment. 1993.
Engineering-Science. Installation Restoration Proiram Phase 1m Records Search and Statement of
Work. Elmendorf Air Force Base. Alaska. 1983.
Harding L.awson. Installation Restoration Proiram Phase II Staie 3 Work Plan. Elmendorf Air Force
&lse. Alaska. 1988.
JlMM/Han:a Environmental. Environmental Restoration Proiect: Field Activities. Data Analysis. 1988.
Radian Corporation. Environmental Baseline Assessment. NOAA Research Station. Elmendorf AFB.
AlilW. 1993a.
Radian Corporation. Limited Field Investiiation. Operable Unit 7. Elmendorf AFB. Alaska. 1993b.
U.S. Air Force. Elmendorf Air Force Base. Alaska. Basewide Backiround Samplini Report. 1993.
U.S. Air Force. Proposed Plan. Operable Unit 6. I 996a.
U.S. Air Force. Remedial InvestiiationlFeasibili~ Study Report. Operable Unit 6. 1996b.
January 1997
8-1
OU 6 ROD, Final
."
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[This page intentionally left blank.]
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PART III
RESPONSIVENESS SUMMARY
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PART III. RESPONSIVENESS SUMMARY
. Public Input into the OU 6 Selected Remedy
The primary avenues of public input have been through the Proposed Plan and public
comment period. The Proposed Plan for OU 6 was issued to the public on I April 1996. This began a
!public comment period that ended on 3 May 1996. To encourage public comment, the USAF inserted a
pre-addressed, written comment form in distributed copies of the Proposed Plan. The comment forms
were also distributed at the 17 April 1996 public meeting, held at the Regal Alaskan Hotel in Anchorage,
Alaska.
The public meeting to receive comments on the Proposed Plan was attended byapproxi-
mately 30 people, including 16 representatives from the Restoration Advisory Board (RAB). Oral
(;omments were received from three members of the public. Prior to the conclusion of the public
comment period, four written comments were received.
All comments received are documented in the administrative record file for the site. A
transcript of the public meeting is available for public review at the site information repositories. The
repositorie:s are located at the Bureau of Land Management's Alaska Resources Library and the
University of Alaska at Anchorage's Consortium Library. Public comments, relevant to OU 6 and/or the
environmental restoration program at Elmendorf, are presented below and have been paraphrased for
greater clarity. This ROD is based on the documents in the Administrative Record and comments
received from the public.
Response to Written Public Comment:
Public Comment I:
The Department of Environmental Conservation from the State of Alaska had a
comment on Landfill Site LF02.
The Remedial Investigation had indicated that while there was lead
contamination in excess of 6000 mg/kg, it was present predominantly in soils
greater than two feet deep. With this assumption, the Air Force, EPA, and
ADEC decided that the soil and vegetative cap in existence on the site was
sufficient to isolate this lead contamination from any receptors of concern.
ADEC has since received data (from a University of Washington study)
indicating that there is lead contaminated in soil in excess of 1000 mg/kg in soil
less than two feet deep.
ADEC no longer considers the present cover sufficient to meet the final cover
requirements of 18 AAC 60. Since this shallow soil contamination seems to be
confined to discrete areas, an additional cover will need to be placed only where
lead levels in excess of 500 mg/kg are present in the top two feet of soil. .
USAF Response:
Three limited soil covers were included in the selected alternative for LF02 soils.
Surface soil areas with lead contamination greater than 500 mg/kg will be
covered with 2 feet of soil. These covers are needed to prevent exposure to lead
pursuant to CERCLA, but they will also comply with 18 AAC 60.390.
III-I
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Public Comment 2:
USAF Response:
The following comment was received from the Anchorage Waterways Council.
The Anchorage" Waterways Council (A WC) is happy to learn of the Air Force's
efforts to clean up Site LF02, but due to its proximity to Ship Creek, the A WC
believes that a more aggressive cleanup regimen is warranted.
Both shallow and deep soils at LF02 are significantly contaminated with fuels
and/or their decomposition products. Moreover, area groundwater
concentrations of several organic solvents are high enough to require cleanup
due to increased cancer risks. As far as we know now, this groundwater is not
being used as a source of human drinking water, but A WC does not agree that
"no significant cumulative impacts" to Ship Creek exist. This landfill and its
leachate plume represent a threat to the biota of the Ship Creek ecosystem and,
through concentrating organisms (fish), to people at present and in the future.
Until these contaminated soils are excavated and removed for treatment,
groundwater contamination cannot be expected to decline.
A number of different agencies and groups are investing heavily in the Ship
Creek riparian corridor. Past adverse effects on the Creek, both industrial and
military, have been acknowledged, studied and scheduled for mitigation.
Municipal planners intend to include the corridor in the city-wide bike trail
system. Much money, human energy and creativity are being spent to make
Ship Creek once again a healthy stream and a community asset. Any significant
source of carcinogenic groundwater pollutants, such as those a~ LF02, work
against these efforts.
Groundwater modeling was conducted for LF02 in the Remedial
InvestigationlFeasibility Study (USAF, 1996). This modeling indicated that
volatile organic contaminants in the groundwater will not migrate to Ship Creek
in concentrations that will adversely affect human health or the ecosystem. The
selected alternative for LF02 groundwater includes biannual monitoring of the
groundwater. This monitoring will indicate if contaminant concentrations
change. Groundwater data will be reviewed annually to ensure that Ship Creek
is protected through the sampling of wells between LF02 and Ship Creek.
Provisions are built into this Record of Decision to take more aggressive action
at LF02 if Ship Creek is threatened.
The Air Force has also undertaken considerable other precautions to ensure that
contamination detected on the base does not adversely impact Ship Creek. To
accurately depict the groundwater contaminant modeling conducted for sites
upgradient of Ship Creek, an extensive study of the creek was conducted to
determine how groundwater interacts with the water in the creek, and how that
relationship changes with the varying water levels encountered in Ship Creek
throughout the year. Another study was conducted to determine what impacts, if
any, have resulted from contamination to date on benthic organisms in Ship
Creek. This study included sampling of the sediments and organism tissues in
Ship Creek. No adverse impacts were detected. A third study was undertaken to
calculate the potential future cumulative risk to organisms in Ship Creek. All of
1II-2
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jPublic Co.mment 3:
lUSAF Re~.ponse:
!Public Comment 4:
USAF Response:
the sites on base addressed in previous risk assessments were included in this
study. Again, no future adverse impacts were predicted. Finally, to ensure the
protectiveness of Ship Creek, monthly sampling of the water in Ship Creek is
being conducted at eight locations along the base boundary. These samples are
analyzed for the constituents detected in those sites on base upgradient of Ship
Creek. To date, no adverse impacts of the water in Ship Creek have been
detected.
One written comment indicated "Looks like good choices of the various action
proposals. "
No response required.
Information was submitted on the Seal of the Treasury of North America.
This information was not found to be relevant to the proposed remediation at
OU6.
J~esponse to Oral Public Comments:
J)ublic Comment 1:
USAF Re!ipOnse:
I)ublic Comment 2:
USAF Res:ponse:
I.ublic Comment 3:
USAF Resiponse:
Could you tell us what the air sparging is?
Air sparging is covered under Alternative 6. Air sparging involves blowing air,
though a pipe, down a well 'and discharging it below the groundwater table. This
accomplishes two functions. First, it strips contaminants out of the groundwater
and releases them to the air. Second, it adds dissolved oxygen to the
groundwater which enhances the biodegradation of the contaminants in the
groundwater.
What is the energy consumption of the bioventing system at WPI4 and of the
high-vacuum extraction system at SO 15?
That information was not readily available at the Public Meeting, however, the
information was subsequently gathered as is presented below:
Bioventing at WPI4: 1,700 kw-hrs per month
High-vacuum Extraction at SO 15: 30,800 kw-hrs per month
The slides gave a good definition of all the alternatives and which ones were the
preferred alternatives, but there was nothing that gave a definition of the specific
problems at each site.
That information was presented at the last RAB meeting and was summarized in .
III-3
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the meeting minutes. The infonnation is also available from a number of
sources. It can be found in the Proposed Plan and in the Remedial Investigation
report, both of which are located in the infonnation repositories.
111-4
-------
APPENDIX A
-------
Appendix A
Index to OU 6 Documents in Administrative Record
Date Submitted Document Number Title/Subject Author
4/15/94 039162-039489 Management Plan, Operable Unit 6 . USAF-Elmendorf AFB
4/ I 5/94 039190-039699 Management Plan, Operable Unit 6, Appendix A. Field Sampling Plan USAF-Elmendorf AFB
4/1 5/94 039700-039959 Management Plan, Operable Unit 6, Appendix B, Quality Assurance Project USAF-Elmendorf AFB
Plan
4/15/94 039960-040095 Management Plan, Operable Unit 6, Appendix C, Site Safety and Health Plan USAF-Elmendorf AFB
4/15/94 040096-040169 Management Plan, Operable Unit 6, Appendix 0, Summary of Historical USAF-Elmendorf AFB
Analytical Results For OU6 Source Areas and Base Water Supply Wells 50
and 51
4/15/94 040170-040173 Management Plan, Operable Unit 6, Appendix E, Equations Used For USAF-Elmendorf AFB
Calculation of Risk-Based Concentrations
4/ I 5/94 040174-04020 I Management Plan, Operable Unit 6, Appendix F, Evaluation of Groundwater USAF-Elmendorf AFB
Flow and Transport of Contam inants in The Vadose Zone at Source SD 15
4/1 5/94 040202-040205 Management Plan, Operable Unit 6, Appendix G, Plan Acknowledgments USAF-Elmendorf AFB
6/23/95 061107-061167 No Further Remedial Action Plan, Bunker 64-580 Soil Removal, Appendix E USAF-Elmendorf AFB
9/28/95 054430-054436 Peer Review Report For Elmendorf Operable Unit 6 Remedial HQPACAF/CEVR
InvestigationlFeasibility Study
11/17/95 054484 Public Notice - The Air Force Announces The Availability of Documents, The USAF-Elmendorf AFB
Record of Decision For Operable Unit 4 and The Remedial Investigation/
Feasibility Study for Operable Unit 6
11/19/95 054486 Public Notice - The Air Force Announces The Availability of Documents, The USAF-Elmendorf AFB
Record of Decision For Operable Unit 4 and The Remedial Investigation/
Feasibility Study for Operable Unit 6
A-I
-------
Appendix A
(Continued)
Date Submitted Document Number Title/Subject Author
12/11/95 060913-060925 Response to Comments on Draft Final RIfFS Report. Operable Unit 6 USAF-Elmendorf AFB
12/22/95 060926-060929 Confirmation Notice No. 12. Operable Unit 6. Installation Restoration USAF-Elmendorf AFB
Program, RemediallnvestigationlFeasibility Study - Minutes from 13
December 1995 Meeting to discuss the Preferred Alternatives for OU 6
I /2/96 054407-055351 RemediallnvestigationfFeasibility Study Report, Operable Unit 6 USAF-Elmendorf AFB
1/2/96 055352-055541 RemediallnvestigationlFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix A - Aquifer (Slug) Test Data
l /2/96 055542-055615 Remedial Investigation/Feasibility Study. Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix B - Historical and Other Supporting Data
l /2/96 055616-056049 Remedial Investigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix C - Background Data - Statistics
I /2/96 056050-056083 RemediallnvestigationfFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix 0 - Bench-Scale Desorptiol} Testing For OU6
1/2/96 056084-056155 RemediallnvestigationfFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix E - Geophysical Data
l /2/96 056156-05630 I Remedial Investigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix F - QA/QC Results Summary
I /2/96 056302-056415 RemediallnvestigationlFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix G - Field GC Data
1/2/96 056416-056448 Rcrncdiallnvestigation/Feasibility Study Report. Operable Unit 6, USAF-Elmendorf AFB
Appendix H - Lead and Chloride Field Screening
I /2/96 056449-056512 RemediallnvestigationfFeasibility.Study Report, Operable Unit 6. USAF-Elmendorf AFB
Appendix I - Soil Gas Report
. .
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/
Appendix A
(Continued)
1\
Date Submitted Document Number Title/Subject Author
1/2/96 056513-056685 RemediallnvestigationlFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix J - Field Logs (Soil Boring Logs and Groundwater)
1/2/96 056686-056703 RemediallnvestigationlFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix K - Geotechnical Results
1/2/96 056704-056727 Remedial Investigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix L - Chemistry Appendix
1/2/96 056728-056772 Remedial Investigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix M - Groundwater Monitoring Well Completion Logs
1/2/96 056773-056802 RemediallnvestigationlFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix N - Survey Data
l /2/96 056803-056832 Remedial Investigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix 0 - Waste Management
1 /2/96 056833-057274 RemediallnvestigationlFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix P - Risk Assessment Tables
I /2/96 057275-057778 Remedial Investigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix Q - Field Log Location Forms
1 /2/96 057779-057795 RemediallnvestigationlFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix R - Base Water Supply Well Data
l /2/96 057796-058548 RemediallnvestigationlFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix S - Laboratory Data
l /2/96 058549-058572 Remedial Investigation/Feasibility Study Report, Operable Unit 6, U~AF-Elmendorf AFB
Appendix T - Conceptual Site Model
A-3
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Appendix A
(Continued)
Date Submitted Document Number Title/Subject Author
1/2/96 058573-058607 Remediallnvestigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix U - Fate and Transport
1/2/96 058608-058629 Remediallnvestigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix V - Groundwater Modeling Results For Sources
1/2/96 058630-058643 Remediallnvestigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix W - Additional Data Collected During The OU6 RI
1/2/96 058644-058651 Remediallnvestigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix X - Preliminary Remediation Goals and Contaminants of Concern
(COC)
1/2/96 058652-05870 I Remedial Investigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix Y - Identification of Preliminary ARARs
1/2/96 058702-058853 Remediallnvestigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix Z - Calculation Sheets and Other Documentation
1/2/96 058854-059147 Remediallnvestigation/Feasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix AA - Cost Estimates
1/2/96 059148-059395 RemediallnvestigationiFeasibility Study Report, Operable Unit 6, USAF-Elmendorf AFB
Appendix BB - Elmendorf OU6 FS Addendum 1995 Investigation
3/6/96 06100 1-06 1004 Comments on OU 6 Draft Proposed Plan, February 1996 USAF-Elmendorf AFB
3/8/96 061005-061011 Comments on Draft Proposed Plan for Operable Unit 6 USAF-Elmendorf AFB
3/22/96 061062 Public Notice - The Air Force Announces a Public Comment Period and A USAF-Elmendorf AFB
Public Information Meeting, The Proposed Plan for Final Remedial Action,
Operable Unit 6, Elmendorf AFB, AK
4/1/96 061065 No Further Action Plan for SS 19 USAF-Elmendorf AFB
-------
Appendix A
(Continued)
Date Submitted Document Number Title/Subject Author
4/1 /96 060977 -061000 Elmendorf AFB - OU 6, The Proposed Plan for Remedial Action USAF-Elmendorf AFB
4/1/96 061066-061093 No Further Action Plan, Bunker 64-580 Soil Removal USAF-Elmendorf AFB
4/1/96 061094-061096 No Further Action Plan, Bunker 64-580 Soil Removal- Appendix A USAF-Elmendorf AFB
4/1/96 061097 -061099 No Further Action Remedial Action Plan, Bunker 64-580 Soil Removal, USAF-Elmendorf AFB
Appendix B
4/ I /96 061102-061106 No Further Action Remedial Action Plan, Bunker 64-580 Soil Removal, USA F.-Elmendorf AFB
Appendix 0
4/ I /96 061168-061467 No Further Action Remedial Action Plan, Bunker 64-580 Soil Removal, USAF-Elmendorf AFB
Appendix F
4/9/96 061704-061720 Public Response for OU 6 Proposed Plan USAF-Elmendorf AFB
4/ I 0/96 061063-061064 Public Response for OU 6 Proposed Plan USAF-Elmendorf AFB
4/17/96 061614-061662 Operable Unit 6 Public Meeting, Elmendorf Air Force Base Restoration USAF-Elmendorf AFB
Advisory Board
4/29/96 061663-061664 Public Response for OU 6 Proposed Plan USAF-Elmendorf AFB
5/ I /96 061665 Operable Unit 6, Landfill Site LF02 USAF-Elmendorf AFB
7/1/96 -- LF04 Treatability Study Workplan, Operable Unit 6 USAF-Elmendorf AFB
7/ I /96 -- LF04 Treatability Study WorlCplan, Operable Unit 6, Appendix A - Site Health USAF-Elmendorf AFB
and Safety Plan
7/1/96 -- LF04 Treatability Study Workplan, Operable Unit 6, Appendix B - Waste USAF-Elmendorf AFB
Management Plan
9/17/96 062026-062039 LF04 Treatability Study Workplan/Scope of Work, Operable Unit 6 USAF-Elmendorf AFB
~,
-
A-5
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Appendix A
(Continued)
Date Submitted Document Number Title/Subject Author
9/17/96 062040-062043 LF04 Treatability Study Workplan/Scope of Work, Operable Unit 6, USAF-Elmendorf AFB
Appendix A . Site Health and Safety Plan
9/17/96 062044-062047 LF04 Treatability Study Work plan/Scope of Work, Operable Unit 6, Appendix USAF-Elmendorf AFB
B - Waste Management Plan
...
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