EPA Superfund
Record of Decision:
Williams Air Force Base
OU5
Chandler, AZ
10/14/1997
PB98-964508
EPA 541-R98-051
October 1998
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INSTALLATION RESTORATION PROGRAM
WILLIAMS AIR FORCE BASE, ARIZONA
FINAL
RECORD OF DECISION
OPERABLE UNIT 5
CONTRACT NUMBER F41624-94-D-8047, ORDER D0011
Project No. 409881
September 1997
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Williams Air Force Base, Arizona
Final
Record of Decision
Operable Unit 5
Prepared for:
Air Force Center for Environmental Excellence
HSC/PKVCB
Headquarters Human Systems Center
Brooks Air Force Base, Texas 78235-5353
Delivery Order 0011
Project No. 409881
Prepared by:
IT Corporation
312 Directors Drive
Knoxville, Tennessee 37923
September 1997
KN/3739/3739.COV/9-2-97(14:7pmyFl/E(2-l4.97)
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Table of Contents.
Page
List of Tables iv
List of Figures v
List of Acronyms vi
1.0 Declaration 1-1
1.1 Site Name and Location 1-1
1.2 Statement and Basis of Purpose 1-1
1.3 Description of the Selected Remedy 1-2
1.4 Declaration Statement 1-3
2.0 Decision Summary 2-1
2.1 Site Name, Location, and Description 2-1
2.1.1 Demography and Land Use 2-1
2.1.2 Air/Climate 2-2
2.1.3 Geology 2-2
2.1.4 Hydrogeology 2-3
2.1.5 Surface Water 2-3
2.2 Site History and Enforcement Activities 2-4
2.2.1 Characterization of Background Conditions 2-7
2.2.1.1 Base-Specific Background Samples 2-7
2.2.2 Site-Specific Descriptions, History, and Investigations 2-8
2.2.2.1 Airfield USTs (ST-25) 2-10
2.2.2.2 Paint Shop Leach Field (WP-27) 2-11
2.2.2.3 Sewage Sludge Trenches (DP-28) 2-13
2.2.2.4 Prime Beef Yard (SS-29) 2-15
2.2.2.5 Golf Course Maintenance Area (SS-31) 2-17
2.2.2.6 Building 1070 (SS-32) 2-18
2.2.2.7 Munitions Incinerator (Facility 1119, SS-34) 2-19
2.2.2.8 Concrete Hardfill Drum Removal Area (LF-26) 2-20
2.2.2.9 Sewage Sludge Stockpile Area (Area 28) 2-22
2.2.3 Demographics 2-23
2.2.4 Geology 2-23
2.2.5 Groundwater 2-23
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Table of Contents (Continued).
Page
2.2.6 Surface Water 2-23
2.2.7 Contaminant Persistence in the Environment 2-24
2.3 Highlights of Community Participation 2-25
3.0 Scope and Role 3-1
4.0 Risk Assessment 4-1
4.1 Introduction 4-1
4.2 Identification of Constituents of Potential Concern 4-2
4.2.1 Data Sources 4-2
4.2.2 Data Validation 4-3
4.2.3 Selection of Contaminants of Potential Concern 4-4
4.2.4 Data Evaluation 4-4
4.2.5 Contaminants of Potential Concern for Subsurface Soil 4-5
4.2.5.1 Airfield USTs (ST-25) 4-5
4.2.5.2 Paint Shop Leach Field (WP-27) 4-5
4.2.5.3 Prime Beef Yard (SS-29) 4-5
4.2.5.4 Golf Course Maintenance Area (SS-31) 4-6
4.2.5.5 Munitions Incinerator (Facility 1119, SS-34) 4-6
4.2.5.6 Concrete Hardfill Drum Removal Area (LF-26) 4-6
4.3 Exposure Assessment 4-6
4.3.1 Characterization of Exposure Setting 4-6
4.3.2 Identification of Potential Exposure Pathways 4-7
4.3.3 Estimation of Exposure 4-7
4.4 Risk Characterization 4-7
4.5 Uncertainty Evaluation 4-9
4.5.1 Terminology 4-9
4.5.2 Sources of Uncertainty 4-9
4.5.2.1 Selection and Quantification of COPC 4-10
4.5.2.2 Exposure Point Concentrations 4-10
4.5.2.3 Selection of Hypothetical Receptors and Potential Exposure
Pathways 4-10
4.5.2.4 Risk Characterization 4-11
4.6 Risk Conclusions 4-11
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Table of Contents (Continued).
Page
5.0 Description of No-Action Alternative 5-1
6.0 Documentation of Significant Changes 6-1
7.0 Responsiveness Summary 7-1
7.1 Overview 7-1
7.2 Background on Community Relations 7-1
7.3 Summary of Comments Received During the Public Comment Period and
Air Force Responses 7-1
7.4 Community Relations Activities at Williams Air Force Base 7-2
8.0 References 8-1
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List of Tables.
Table Title Follows Page
2-1 Cities Surrounding Williams Air Force Base, Arizona 2-1
2-2 Background Inorganic Species Concentrations in Soil 2-7
2-3 Remedial Investigation Sites 2-9
2-4 Summary of Detected Compounds 2-10
4-1 COPC Selected for Sites at OU-5 4-5
4-2 Summary of Risk Evaluation for Sites in OU-5 4-8
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List of Figures.
Figure Title Follows Page
1-1 Site Location Map 1-1
2-1 Site Location Map, Background Surface Soil Samples 2-7
2-2 Site Location Map, Operable Unit 5, East of Runway 2-9
2-3 Site Location Map, Operable Unit 5, West of Runway 2-9
2-4 Soil Removal and Sample Locations Airfield USTs (ST-25) 2-10
2-5 Site Location Map, Former Paint Shop, Bldg. 771, Leach Field (WP-27) 2-12
2-6 Soil Removal and Sample Locations, Former Paint Shop, Bldg. 771,
Leach Field (WP-27) 2-13
2-7 Site Location Map, Sewage Sludge Trenches (DP-28) 2-14
2-8 Site Location Map, Facility 766, Prime Beef Yard (SS-19) 2-15
2-9 Soil Removal and Sample Locations, Facility 766, Prime Beef Yard (SS-29) 2-16
2-10 Site Location Map, Golf Course Maintenance Area (SS-31) 2-17
2-11 Soil Removal and Sampling Locations, Golf Course Maintenance Area (SS-31) 2-18
2-12 Site Location Map, Building 1070 (SS-32) 2-18
2-13 Site Location Map, Facility 1119, Munitions Incinerator (SS-34) 2-19
2-14 Soil Removal and Sampling Locations, Facility 1119, Munitions
Incinerator (SS-34) 2-20
2-15 Sample Location Map, Concrete Hardfill Area (LF-26) 2-20
2-16 Soil Removal and Sampling Locations, Concrete Hardfill Drum
Removal Area (LF-26) 2-22
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List of Acronyms,
ADEQ
ADWR
AFB
AST
ATC
AV
bgs
BHC
CERCLA
CLP
COPC
DDE
DDT
DOD
E/A
EM
EPA
ES
ESD
FFA
FS
FSP
HBGL
HI
HQ
HSP
ILCR
IRP
rr
JP-4
mg/kg
Mg/kg
Arizona Department of Environmental Quality
Arizona Department of Water Resources
Air Force Base
aboveground storage tank
Air Training Command
AeroVironment, Inc.
below ground surface
beta hexachlorocyclohexane
Comprehensive Environmental Response, Compensation, and Liability
Act
Contract Laboratory Program
contaminant of potential concern
dichlorodiphenyldichloroethene
dichJorodiphenyltrichloroethane
U.S. Department of Defense
evaluation/assessment
electromagnetic
U.S. Environmental Protection Agency
Engineering-Science, Inc.
Explanation of Significant Difference
Federal Facilities Agreement
feasibility study
field sampling plan
health-based guidance level
hazard index
hazard quotient
health and safety plan
incremental lifetime cancer risk
Installation Restoration Program
IT Corporation
jet petroleum grade 4
milligrams per kilogram
micrograms per kilogram
KN/3739/J739.CONAW-29-97( 1:
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List Of Acronyms (Continued).
msl mean sea level
NCP National Contingency Plan
NOAA National Oceanic and Atmospheric Administration
NPL National Priorities List
OU Operable Unit
PAH polynuclear aromatic hydrocarbon
PCB polychlorinated biphenyl
PPM priority pollutant metal
PRG preliminary remediation goals
PVC polyvinyl chloride
QAPP quality assurance project plan
QA/QC quality assurance/quality control
RAB Restoration Advisory Board
RCRA Resource Conservation and Recovery Act
RI remedial investigation
ROD record of decision
RWCD Roosevelt Water Control District
SARA Superfund Amendment and Reauthorization Act
SLRA screening level risk assessment
SVOC semi volatile organic compound
TPH total petroleum hydrocarbon
TRC Technical Review Committee
TWO Technical Working Group
UCL upper confidence limit
USAF U.S. Air Force
USGS U.S. Geological Survey
UST underground storage tank
VOC volatile organic compound
WWTP wastewater treatment plant
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1.0 Declaration
1.1 Site Name and Location
Williams Air Force Base (AFB) is located in Maricopa County, Mesa, Arizona (Figure l-l). The
following sites constitute Operable Unit (OU) 5:
• Airfield Underground Storage Tanks (UST) (ST-25)
• Paint Shop Leach Field (WP-27)
• Sewage Sludge Trenches (DP-28)
• Prime Beef Yard(SS-29)
• Golf Course Maintenance Area (SS-31)
• Building 1070 (SS-32)
• Munitions Incinerator (Facility 1119, SS-34)
• Concrete Hardfill Drum Removal Area (LF-26)
• Sewage Sludge Stockpile Area (Area 28).
The U.S. Environmental Protection Agency (EPA) issued a guidance in a memorandum on
August 23,1994 that encourages and supports efforts to accelerate and develop streamlined
approaches to the cleanup of hazardous wastes at federal facilities. These sites were selected to
be included as one operable unit, OU-5, based on the results of the evaluation/assessment (E/A)
performed at 30 areas at Williams. It appeared that the nature and extent of contamination was
such that through investigations and/or simple removal actions no further action would be
required.
Following EPA guidance, an action memorandum (IT, 1995a) was issued in June 1995 outlining
removal actions recommended for OU-5 sites at Williams AFB. These removal actions were
completed in July 1995 . Excavations at six of the OU-5 sites noted above were performed to
remove suspected contamination previously identified in the final and Phase II
evaluation/assessment (E/A) reports, facilities assessment report, or during other investigations.
Confirmatory soil samples were collected in accordance with Section 4.1 of the approved field
sampling plan (FSP) (FT Corporation [IT], 1995b) to verify that contaminants with concentra-
tions exceeding the Arizona health-based guidance level (HBGL) or EPA Region EX residential
preliminary remediation goals (PRG) had been removed and properly disposed.
1.2 Statement and Basis of Purpose
This record of decision (ROD) substantiates the no-action remedy for the sites that constitute
OU-5 at Williams AFB. The ROD was developed in accordance with the Comprehensive
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SKY HARBOR
INTL. AIRPORT
FIGURE 1-1
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SCALE
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10 FEET
SITE LOCATION MAP
WILLIAMS AIR FORCE BASE
PHOENIX, ARIZONA
INTERNATIONAL
TECHNOLOGY
CORPORATION
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Environmental Response, Compensation, and Liability Act (CERCLA), as amended by the
Superfund Amendment and Reauthorization Act (SARA), and, to the extent practicable, the
National Contingency Plan (NCP). This decision is based on the Administrative Record for this
OU.
EPA and state of Arizona concur with the selected remedy for OU-5.
This ROD only reiterates that cleanup via capping of the Sewage Sludge Trenches (DP-28) were
included as part of the final remedy for the Landfill (LF-04) in OU-1 (FT, 1995c). The capping of
DP-28 was also included as part of the Explanation of Significant Difference (ESD) that was
approved in June 1994.
1.3 Description of the Selected Remedy
As with many Superfund sites, the environmental problems at Williams AFB are complex. As a
result, the U.S. Air Force (USAF) has organized the work into the following OUs.
• OU-1 addresses soil and groundwater contamination at the following ten sites:
- Landfill (LF-04)
- Fire Protection Training Area No. 1 (FT-03)
- Northwest Drainage System (SD-10)
- Radioactive Instrumentation Burial Area (RW-11)
- Pesticide Burial Area (DP-13)
- Hazardous Materials Storage Area (SS-01)
- USTs at four areas (ST-05, ST-06, ST-07, and ST-08).
• OU-2 addresses soil and groundwater at the Liquid Fuels Storage Area (ST-12).
• OU-3 addresses soil and groundwater at the following two sites:
- Fire Protection Training Area No. 2 (FT-02)
- Southwest Drainage System (SD-09).
• OU-4 addresses investigations of contamination at 11 sites.
- Electroplating/Chemical Cleaning (Facility 1085, Site SS-16)
- Old Pesticide/Paint Shop (Facility 742, Site SS-17) (This has been moved to
OU-6)
- Oil/Water Separator - Petroleum, Oil, and Lubricant (Facility 550, Site SD-18)
- Former Skeet Range at Former South Desert Village (Site SS-19)
- Firing Range/Skeet Range (Facility 927, Site SS-20)
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- Facilities 1020 and 1051 (Site SS-21)
- Aboveground Storage Tanks (AST) 556 and 557 (Site ST-22)
- Building 1069 (Site SS-23)
- Building 1010 (Site SS-24)
- Concrete Hardfill Area (Site LF-26)
- Facility 1004 (Area 14).
• OU-5 addresses soil contamination actions at the nine sites listed in Section 1.1.
• OU-6 addresses soil and potential groundwater contamination at the Old
Pesticide/Paint-Shop (Facility 724, Site SS-17).
The US AF, EPA, and state of Arizona have approved RODs implementing cleanup remedies for
OU-1, OU-2, and OU-3 sites. The deep soils at ST-12 (unsaturated soils below 25 feet) were
included in an amendment to the OU-2 ROD. Investigations and feasibility study (FS) have
been completed for OU-4 sites. Investigations, RI Report, Proposed Plan, and ROD are to be
completed at OU-6. OU-5 is the subject of this ROD. This ROD recommends no action because
previous removal actions resulting from the OU-5 action memorandum have either lowered the
contamination levels below Arizona HBGL or EPA Region IX residential PRGs or the risk
associated with the remaining contamination concentration will not pose an unacceptable risk to
human health and the environment.
1.4 Declaration Statement
Previous removal actions associated with the OU-5 action memorandum have lowered the health
risks associated with exposure to contaminated soil at the OU-5 sites so that they pose no
unacceptable risk to human health or the environment under a conservative screening level
residential exposure scenario. Therefore, no further remedial action is required for soil in any of
the sites identified in OU-5. Soil removal, sampling, and analyses occurred during the July 1995
field activities. No action is required for groundwater as the result of any contaminants at these
sites because soil contamination was limited to shallow surface soil (i.e., less than 25 feet) and
there is no contaminant source. These two factors when combined with depth to groundwater of
150 feet eliminated concerns for groundwater contamination. Because the concentrations of
contaminants in the residual soil are within health-protective levels, and no engineering controls
were required as part of previous removal action, the OU-5 sites may be released for unrestricted
use and no 5-year review will be required for any OU-5 site.
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This record of decision for OU-5 at Williams AFB, Arizona may be executed and delivered in
any number of counterparts, each of which when executed and delivered shall be deemed to be
an original, but such counterparts shall together constitute one and the same document.
Albert F. Lowas, Actjrijf Diredwy
U.S. Air Force, Base (/onvetskm Agency
Date
Daniel Opalski, Director
Federal Facilities Cleanup Office
U.S. Environmental Protection Agency, Region DC
' Date
Russell F. Rhoades, Director
Arizona Department of Environmental Quality
Date
RitaTearson, Director
Arizona Department of Water Resources
Date
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1-4
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2.0 Decision Summary
2.1 Site Name, Location, and Description
Williams AFB located in Maricopa County, Arizona is approximately 30 miles southeast of
Phoenix and just east of Chandler (Figure 1-1). The Base is relatively isolated from any large
metropolitan area. Smaller urban areas such as Mesa, Chandler, Gilbert, and Apache Junction
are located 5 to 15 miles northeast and northwest of the Base. The Queen Creek and Chandler
Heights areas are approximately 5 miles south and west of the Base boundary, respectively.
Table 2-1 lists these towns and others with distance and direction from Williams AFB; the
population of the towns are included. These areas are separated from the Base by cultivated and
uncultivated land.
Williams AFB was constructed on 4,042 acres of government land in 1941 to be used as a flight
training base. Training activities with jet aircraft began in 1949. Runway and airfield operations,
industrial areas, housing, and recreational facilities are located on the Base. In 1992, as a result
of U.S. Department of Defense (DOD) downsizing, the Base was recommended for closure and
subsequently closed September 30, 1993.
2.1.1 Demography and Land Use
During its active status, 3,029 military personnel and 869 civilian employees were stationed at
the Base. The total population actually living on Base, including dependents, was approximately
2,700. Many of the military personnel lived off Base in one of the surrounding areas. On an
average workday, the population of the Base increased to more than 5,000 because of the influx
of both civilian employees and military personnel living off Base (Cost Branch Controller
Division, 1987).
The Base is surrounded primarily by agricultural land in a valley that has had a long history of
intensive agricultural use, predominantly for crops of citrus, cotton, and alfalfa.
A development plan for the region (Sunregion Associates, 1987), if implemented, will dra-
matically alter the region surrounding Williams AFB. The portions of the development plan of
most importance to the Base are the East Mesa Subarea Plan and the Queen Creek-Chandler
Heights Plan. The former proposes development for portions of the City of Mesa, the Town of
Gilbert, the City of Apache Junction, and the land area north of Williams AFB. The proposed
land area for the Queen Creek-Chandler Heights Plan is east of Chandler, just south of the Base
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Table 2-1
Cities Surrounding Williams Air Force Base, Arizona
City
Apache Junction
Chandler
Gilbert
Mesa
Queen Creek
Tempe
Phoenix
Direction Relative to
Williams AFB
North-Northeast
West
Northwest
North-Northwest
South
Northwest
Northwest
Distance from
Williams AFB (miles)
10
5
5
15
5
20
25
Population3
21.354
119.227
51,074
313,649
3082
144.289
1,048.949
July 1,1994 Census.
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in the approximate location of the Town of Queen Creek. The plan is to develop the proposed
area residentially and commercially over a 25-year period. If implemented, this development
will dramatically impact the demographics and population around the Base. The transition of
Williams AFB to the Williams Gateway Airport Authority will also impact the region.
2.1.2 Air/Climate
The climate of Williams AFB is similar to that of Phoenix and the rest of the Salt River Valley.
The temperature ranges from very hot in the summer to mild in winter. Rain comes mostly in
two seasons: from late November until early April, and in July and August. Average annual
precipitation is approximately 7.1 inches. Humidity ranges from approximately 30 percent in
winter to 10 percent in summer. Williams AFB is also characterized by light winds. The mean
annual pan evaporation is approximately 100 inches and the annual lake evaporation for the area
is approximately 72 inches (National Oceanic and Atmospheric Administration [NOAA], 1977).
2.1.3 Geology
Williams AFB lies in the eastern portion of the Basin and Range Physiographic Lowlands
Province of south-central Arizona, which is located in the Salt River Valley. The local to-
pography is controlled by large-scale normal faulting that has resulted in the formation of broad,
flat, alluvial-filled valleys separated by steep isolated hills and mountain ranges. Arizona
Department of Water Resource's hydrologic maps show the Base bounded to the north by the
Usery Mountains, to the east by the Superstition Mountains, to the south by the Santan Moun-
tains, and to the west by South Mountain.
The topography of the Base slopes gently to the west with a generally less than 1 percent grade.
Elevations range from 1,326 feet above mean sea level (msl) on the west side of the Base to
1,390 feet above msl at the southeast corner of the Base.
According to Laney and Hahn (1986), the area of the Base is underlain by six geologic units:
crystalline rocks, extrusive rocks, red unit, lower unit, middle unit, and upper unit. The crys-
talline and extrusive rocks compose the surrounding mountains and the basement complex
underlying the consolidated and unconsolidated sediments of the valley. The four units overlying
the basement complex are of sedimentary origin and have the surrounding mountains and local
drainage as their source areas.
The red unit immediately overlies the basement complex and is composed of well-cemented
breccia, conglomerate, sandstone, and siltstone of continental origin with interbedded extrusive
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flow rocks. The lower unit overlies the red unit and consists of playa, alluvial fan, and fluvial
deposits with evaporites and interbedded basaltic flows present in lower sections (Laney and
Hahn, 1986). The middle unit overlies the lower unit and is composed of playa, alluvial fan, and
fluvial deposits with no associated evaporites. The middle unit received its sediment primarily
from the Salt River, whereas the red and lower units had the local mountains as the principal
source. The youngest unit in the stratigraphic sequence is referred to as the upper unit. This unit
consists of channel, floodplain, terrace, and alluvial fan deposits of largely unconsolidated gravel,
sand, silt, and clay.
Two major soil associations are found in the vicinity of Williams AFB. The Mohall-Contine
Association is found over much of the Base, and the Gillman-Estrella-Avondale Association is
found at the southern boundary of the Base. The Mohall-Contine and the Gillman-Estrella-
Avondale Associations have generally the same characteristics, being well drained and nearly
level with slopes of less than 1 percent.
2.1.4 Hydrogeology
Groundwater elevation contour maps have been produced for the western half of the Base, where
groundwater monitoring wells exist. This information is presented in the OU-1 and OU-2
remedial investigation (RI) reports (IT, 1992a,b), and the OU-3 RI report (IT, 1994a). The maps
indicate that groundwater flows to the north and east on a Basewide scale. These maps are
consistent with other groundwater elevation contour maps presented for the area (Laney and
Hahn, 1986; AeroVironment, Inc. [AV], 1987).
A general rise in groundwater elevations has been observed in monitoring periods from
December 1989 to present at a rate of 3 to 5 feet per year. Rising groundwater levels may be
attributed to decreased local pumping due to urbanization and larger surface water use, increased
recharge from additional agricultural irrigation, and increased recharge from unusually rainy
periods over the past 10 to 15 years.
There are at least 90 domestic permitted wells within a 3-mile radius of the Base. These wells
are not affected by contamination at OU-5.
2.1.5 Surface Water
There are no major surface water bodies within a 10-mile radius of the Base. The Base lies
between the 100-year and 500-year flood level for streams in the Gila River Basin (U.S. Depart-
ment of Housing and Urban Development, 1979). Storm drainage on the Base is directed to a
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2-3
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combination of open channels used to drain most of the Base and underground drainage struc-
tures. Storm drainage from the Base flows either to the Roosevelt Water Control District
(RWCD) floodway that flows southward in the vicinity of the Base or directly to the floodway
west of the Base, or into the wastewater treatment plant.
2.2 Site History and Enforcement Activities
Williams AFB was a flight training base that opened in 1942. It was immediately commissioned
as a flight training school, and training activities with jet aircraft began in 1949. Throughout its
history, pilot training was the primary activity at Williams AFB. At various times, bombardier,
bomber pilot, instrument bombing specialist, and fighter gunnery training schools were also
housed on Base. Over the years, a wide variety and large number of aircraft have been housed at
Williams AFB.
The Installation Restoration Program (IRP) was implemented by the DOD in 1980 to identify and
control environmental contamination from past hazardous materials use and disposal activities at
USAF installations. The IRP is DOD's equivalent of the national Superfund program. SARA,
passed by Congress in 1986, required cleanup of federal facilities to meet Superfund
requirements.
IRP guidance was received at Williams AFB in July 1983 and the initial assessment study
(designated as Phase I) was completed by Engineering-Science, Inc. (ES) in 1984. Based on a
review of available records pertaining to chemical handling and disposal practices, interviews
with site personnel, and a site survey of activities at Williams AFB, the study identified the
following nine potential sites where hazardous materials have been handled or disposed:
• Landfill (LF-04)
• Fire Protection Training Area No. 1 (FT-03)
• Fire Protection Training Area No. 2 (FT-02)
• Northwest Drainage System (SD-10)
• Southwest Drainage System (SD-09)
• Radioactive Instrumentation Burial Area (RW-11)
• Pesticide Burial Area (DP-13)
• Hazardous Materials Storage Area (SS-01)
• Liquid Fuels Storage Area (ST-12).
A second investigation (designated as Phase II) was conducted by AV from September 1984 to
December 1985 (AV, 1986). This investigation was initiated to confirm the information in the
ES report and to verify the presence and quantify the extent of contamination. In 1987, AV
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completed an additional investigation (Phase n, Stage 2) to define the most likely pathways for
contaminant migration from each site and to confirm the presence or absence of contamination
along those pathways.
In 1987, as a result of AV investigations, IT, under a contract with Martin Marietta Energy
Systems, Inc. through the Hazardous Waste Remedial Actions Program, performed a simple
remedial action (IT, 1987a). This activity involved designing soil cementing and a concrete cap
for approximately 350 feet of the uppermost portion of SD-09. Plans and specifications were
issued in September 1987 (IT, 1987b) and the work was completed that year.
In October 1988, the Air Training Command (ATC) contracted Martin Marietta Energy Systems
and its subcontractor, IT, through the U.S. Department of Energy to complete the RI/FS,
proposed plan, and ROD at Williams AFB. As part of these efforts, a work plan and quality
assurance project plan (QAPP) (IT, 199la), which includes a health and safety plan (HSP), and
an FSP (IT, 1991b), were issued. The continuation of the RI was initiated in January 1989. The
sites investigated include the nine original sites plus four UST sites (ST-05, ST-06, ST-07, ST-
08).
Williams AFB was added to the National Priorities List (NPL) on November 21, 1989. The NPL
primarily serves as an information tool for EPA to identify sites that possibly warrant further
investigation and remedial action.
As a consequence of inclusion on the NPL listing, negotiations were completed and a Federal
Facilities Agreement (FFA) was signed on September 21, 1990. The FFA establishes a co-
operative and participatory framework among the federal and state agency members, defines their
roles and responsibilities, and develops a process to resolve any disputes that may arise during
the study and execution phases of the IRP. In addition, the FFA prioritizes and schedules the
investigation and remedial actions at Williams AFB through the designation of OUs that aid in
managing these activities. Parties to the FFA include the USAF, the EPA, the Arizona De-
partment of Environmental Quality (ADEQ), and the Arizona Department of Water Resources
(ADWR).
The FFA divided the Base into two OUs. OU-1 included eight areas identified in previous
investigations, plus four UST areas (IT, 1992a; 1994b,c). OU-2 comprised the groundwater
contamination and shallow (less than 25 feet) soil contamination at the Liquid Fuels Storage
Area (FT, 1992b,c,d). OU-3 was subsequently identified to consider sites not included in OU-1,
KN/3739/3739.TXT/8-29-97C31 pm)\F/E(2-13-97) 2-5
-------
the portion of the storm line from Building 53 to the headworks of SD-09, and the Fire Protection
Training Area No. 2. OU-1, OU-2, and OU-3 sites have been investigated and the results
reported (FT, 1994a).
In 1992, after the Base was nominated for closure, there was a question of whether all the areas
on the Base with potential contamination had been included in the administrative record. This
question led to the facilities assessment, which began in February 1992 and was concluded in
1993 (FT, 1993a).
The facilities assessment report documented the actions that have been taken to assess facilities
not included under the ERP. The report also reviewed the background of each facility and any
contamination that might pose a risk to human health or the environment at that location. This
process resulted in assessing 92 facilities/areas. Forty-nine facilities/areas were recommended to
be eliminated from further consideration, 29 were recommended for further investigation, 12
were recommended for inclusion as part of the State Compliance Program, and 1 was rec-
ommended for addition as an IRP site. One area (Southwest Drainage System) was already
identified as an IRP site. The Golf Course Maintenance Area was subsequently added to the sites
recommended for further investigation, increasing the list for further investigation to 30 areas.
In 1993, field and sampling activities were conducted by FT at the 30 areas designated for the
E/A. The purpose of this investigation was to evaluate the areas for the presence or absence of
contamination that may have resulted from operations at the Base. The resultant E/A report (IT,
1994c) summarizes the results of this investigation. Areas where the presence and extent of
contamination was confirmed were recommended for limited removal action and/or risk
screening and were designated as OU-5 sites. Areas recommended for further investigation
under CERCLA were designated as OU-4 sites.
A ROD for OU-2 was signed in December 1992. Deep soil at ST-12 from (25 feet to
groundwater) was incorporated into OU-3 for final characterization of the vertical and area!
extent of contamination. Once this characterization was completed, the deep soils were
reincorporated into OU-2 via an OU-2 ROD amendment. The OU-2 ROD amendment was
signed in August 1996. A ROD for OU-1 was signed May 18, 1994 and a ROD for OU-3 was
signed in May 1996.
KN/3739/37J9.TXT/8-29-97(:Slpm)\F/E<2-l3-97) 2-6
-------
This ROD addresses remedial actions for OU-5, which is composed of the following sites:
• Airfield Underground Storage Tanks (Site ST-25)
• Paint Shop Leach Field (Site WP-27)
• Sewage Sludge Trenches (Site DP-28)
• Prime Beef Yard (SS-29)
• Golf Course Maintenance Area (SS-31)
• Building 1070 (SS-32)
• Munitions Incinerator (Facility 1119, SS-34)
• Concrete Hardfill Drum Removal Area (LF-26)
• Sewage Sludge Stockpile Area (Area 28).
The criteria used to determine which sites would be included in OU5, history of past waste
practices, environmental investigations, enforcement activities, and remedial actions for each
OU-5 site is presented in the following sections.
2.2.1 Characterization of Background Conditions
Regional background concentrations for inorganic species in soils were obtained from surficial
soils in Gila, Maricopa, Pima, Pinal, and Yuma Counties in Arizona. Each of the U.S. Geo-
logical Survey (USGS) samples was collected from alluvial materials with a geologic provenance
similar to the Base. The regional ranges of inorganic species concentrations are shown in Table
2-2. For information regarding elements that were not analyzed by the USGS, normal soil ranges
were obtained from Heavy Metals in Soils (Alloway, 1990). The data in the Alloway report are
based on worldwide averages for uncontaminated soils and have been included to provide
additional perspective for values measured at the Base.
All organics generally associated with anthropogenic activity were considered to be site-related,
with the exception of polynuclear aromatic hydrocarbon (PAH). Background concentrations
were considered for PAHs because these compounds can be naturally distributed throughout the
environment, primarily from the combustion of fossil fuels with subsequent atmospheric
dispersion and deposition (Gschwend and Hites, 1981; Kawamura and Kaplan, 1983; LaFlamme
and Hites, 1978; Thomas, 1986).
2.2.1.1 Base-Specific Background Samples
There was agreement among the Parties to the FFA that it was necessary to establish Base-
specific background levels for inorganic constituents in surface soil as recommended in the OU-1
RI report (IT, 1992a). It was on this basis that ten Base-specific background surface soil samples
were collected and analyzed in September 1993. The three areas sampled (Figure 2-1) were
KN/J739/3739.TXT/8-»-97(:51pmW:/E<2-IJ-97) 2-7
-------
t • *>U W tf^OKMlll* IM Ml* WV«-
I*> ItM* IBW«lllt*Wt Mil,
I. ••*• « •MI M
> FIGURE 2-1
WILLIAMS AIR FORCE BASE
-/ SITE LOCATION MAP
\ BACKGROUND SURFACE
1 SOIL SAMPLES
WILLIAMS Aif> FORCE BASC
PHOENIX, ARIZONA
-------
Table 2-2
Background Inorganic Species Concentrations in Soil
Operable Unit 5
Williams Air Force Base
Constituent
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
Soil (mg/kg)
Base-Specific
Range8
NDC(<12)
2.3 to 4.3
NA"
1.0 to 1.6
ND(<1)
16.9 to 24.8
NA
ND (<5)
10.4 to 19.4
ND (<0.2)
15.6 to 24.7
0.21 to 0.24
ND(<2)
ND (<2)
ND (<4)
Regional
Range6
<1
2 to 97
__•
1.0 to 1.5
0.01 to 2.01
15 to 100
„
15 to 200
10to100
0.01 to 0.5f
7 to 50
0.1 to 5f
0.01 to 8r
0.1 to 0.8'
25 to 150
"The range presents the tow and high values for the ten samples.
"Data obtained from surficial soils in Gila, Caricopy, Pima, and Yuma counties.
CND - Not detected.
dNA - Not analyzed because this chemical is not a priority pollutant metal. Base-specific
background samples were analyzed for priority pollutant metals in accordance with the approved
work plan.
*•-' Not available.
fOata obtained from Heavy Metals in Soils (Alloway, 1990).
KN/3739/3739.2-2/08-29-97(l2:51pm)\Fl\E<2-IJ-97)
-------
-------
selected based on information from aerial photographs, ecological assessment observations, and a
site walk at the Base to determine areas that were undisturbed. Locations were chosen based on
having no historic photographic evidence of activity that would have disturbed the soil and on
visual review of each area to ensure that there had been no recent activity. This factor relied to
an extent on observations from the ecological assessment team, who examined the size and type
of vegetation and absence of any indication of human intrusion. Three locations were selected
based on recommendations from risk assessment personnel so that there would be statistically
significant results compiled from an adequate number of samples. The areas north, south, and
northeast of the runways were designated because they satisfied all criteria. It was recognized
that there could be residual material from jet exhaust, but considering the use of the Base,
prevailing wind direction, and the fact that all surface portions of the Base east of the runways
were disturbed, these areas best represent surface background conditions. Areas off the Base
have been more disturbed than on the Base due to agricultural use, and also could have been
affected by exhaust from jets as well as crop dusting planes. The background metals that were
analyzed for included antimony, arsenic, beryllium, cadmium, chromium, copper, lead, mercury,
nickel, selenium, silver, thallium, and zinc.
The OU-3 FSP addendum (IT, 1993b), and OU-1 RI work plan addendum (FT, 1993c) specified
the exact locations and techniques that were approved by the FFA Parties. Nine surface soil
samples and a duplicate were collected and the analytical results were averaged to determine a
Base-specific background concentration for each inorganic constituent. All Base-specific
background concentrations and the regional range of concentrations detected for inorganic
species in soil are presented in Table 2-2.
Comparison of site inorganic data to background data is performed in the risk assessment
(Section 4.2.3). An inorganic constituent was considered to be present at background levels if
the site mean was less than or equal to the background mean. If the site mean marginally
exceeded the background mean, a student's t-test was performed to determine if the background
concentrations were exceeded (Section 4.2.3).
2.2.2 Site-Specific Descriptions, History, and Investigation
This section includes the site selection criteria, investigation, removal action, and postremoval
sampling for sites at OU-5. Individual site descriptions, histories, and summary of post sampling
results are included in the sections that follow. The site selection criteria used for determining
OU-5 sites was based on results from the investigations in the E/A phase of areas with possible
contamination. These areas were identified from historic photos. The nine areas selected for
KN/3739/3739.TXT/8-29-97051 pmAF/E(2-13-97)
2-8
-------
OU-5 were ones with very low levels of contaminants detected during the E/A phases. The
investigation work plan was written to gain data to the type and any concentration of
contamination in soil at these sites. It was anticipated that the contaminant concentrations would
be low enough to require no further action. Due to the low concentrations of contaminants
measured in soil in the E/A phase, it was determined that no groundwater monitoring wells
would be installed in the OU-5 investigations. The actions at OU-5 were performed prior to the
promulgation of the Arizona Amended Soil Remediation Rules (April, 1996). These rules
address soil concentrations and constituents, which could affect groundwater.
The screening criteria used to determine if remedial action was required at the sites at OU-5
included comparison to: (1) EPA Region DC residential preliminary remediation goals and (2)
base background concentrations for metals in soil. The constituent concentrations were used in a
screening level residential risk assessment (Chapter 4.0) to determine if there was an acceptable
risk to human health. If the risk assessment determined that human health risk would be
acceptable for residential use then no action was required. On the other hand if human health
risk was acceptable for nonresidential use only, a VEMUR would be filed and no other action
would be taken. If the risk criteria for both residential and nonresidential use were exceeded then
a remedial action would have been necessary. In the case of OU-5 all the above criteria were met
so no further action was necessary at any site. See Section 4.0 for the results of the risk
assessment. Descriptions of the nine OU-5 sites and their locations are summarized in Table 2-3
and Figures 2-2 and 2-3.
A summary of the history leading to the site selection; investigation; removal action; and post
removal sampling is included in the following paragraphs. Initially, the areas that constitute these
sites were identified as a result of photogrammetric interpretation of historic aerial photographs.
The areas were identified in the facilities assessment report issued in 1993 as areas requiring
further investigation. The initial assessment and records search of the areas identified was
conducted under the E/A Phase I. The E/A Phase n confirmed the concentrations of
contaminants in the areas and whether these concentrations posed a risk to human health and the
environment. This evaluation was preparatory to consideration in the CERCLA process. Based
on the results of the Phase H E/A, certain areas were designated to be considered for further
investigation under OU-4 because the nature and concentration of contaminants appeared to
eliminate a simple removal action or no action. Immediate removal action was considered
prudent at other sites as specified in the OU-5 action memorandum. The removal actions
specified in the action memorandum were taken at six sites. No action was taken at the
KN/3739/3739.TXT/8-29-97(:5lprn>\F/E<2-l}-97) 2-9
-------
Table 2-3
Remedial Investigation Sites
Operable Unit 5
Williams Air Force Base, Arizona
Site Description
Airfield Underground Storage Tanks
Paint Shop Leach Field
Sewage Sludge Trenches
Prime Beef Yard
Golf Course Maintenance Area
Building 1070
Munitions Incinerator
Concrete Hardfill Drum Removal Area
Sewage Sludge Stockpile Area
Site Number
ST-25
WP-27
DP-28
SS-29
SS-31
SS-32
SS-34
LF-26
N/A
E/A Report Area
2
18
20
26
30
N/A
6
3
28
Building
N/A1
N/A
N/A
N/A
N/A
1070
1119
N/A
N//A
aN/A - Not applicable.
KN/3739/3739.2-3/08-29-97< 12:52pm)\FI \E<2-13-97)
-------
I
I. SMAOCO W»CAS ASt SHOWN Offl.r
10 PROvCC SHC IOCAHO«S v
DO NO! RCPRCStHI 'Mt »C'U«i
of IMC sues.
SCAU
500 COO f£CT
SITE LOCATION MAP
OPERABLE UNIT 5
WEST Of RUNWAY
WILLIAMS AIR FORCE BASC
PHOENIX.
INTERNATIONAL
TECHNOLOGY
CORPORA! iQtj
-------
remaining three sites because either no action was required or action was taken under another
OU.
Each of these nine sites has been investigated, removal action taken where appropriate, and
postremoval samples taken. Soil removal, sampling, and analyses occurred during the July 1995
field activities. These removal actions were performed prior to promulgation of the Arizona
Amended Soil Remediation Rules (April 1996). The nature, extent, and volume of contaminants
are defined under investigations and removal actions, providing justification why no further
action is required based on analytical sample results. Table 2-2 provides the Base-specific and
regional ranges for constituents found at Williams AFB. Table 2-4 provides a summary of the
detected compounds at the OU-5 RI sites. Removal action on the sites accounted for a total of
nine roll-off bins containing the contaminated soil and concrete, and two drums. The roll-off
bins were disposed off site by Allwaste Transportation and Remediation, Phoenix, Arizona.
Chapter 4.0 provides human health risk assessment results to substantiate the no-action
alternatives for those sites where analytical results were of themselves inadequate to draw this
conclusion.
2.2.2.1 Airfield USTs (ST-25)
Site Description and History. The Airfield USTs area is located between the Runway 12R-
30L and Runway 12C-30C, adjacent to Taxiway No. 6 (Figure 2-2). The USTs were believed to
be located approximately 85 feet south of Taxiway No. 6. The area consists of an asphalt turnout
from the taxiway, a concrete pad area, and suspect manway and vent or fill hole to the USTs
(Figure 2-4). There are no buildings near the area.
Several reports indicate that USTs may have been located in the area of the airfield. Reportedly,
at one time the Base had a rapid refueling operation for the airplanes. This would require fuel
tanks to be located near the taxi ways. IRP personnel inspected the airfield on April 10, 1992.
Several pipes had been damaged by lawn mowers along the runways; however, only one pipe
appeared to be a possible fill pipe for a UST or a sump. This pipe is located approximately 120
feet south of Taxiway No. 6. The suspected manway is located north of the concrete pad, and the
vent is south of the pad.
Investigations. During the E/A investigation (IT, 1994c), a geophysical survey of the Airfield
USTs area was performed. Total field magnetic and electromagnetic (EM) conductivity data
KN/3739/3739.TXTffl-29-97(:51pin)\F/E(2-l3-97)
2-10
-------
Table 2-4
Summary of Detected Compounds
OU-5 Remedial Investigation
Williams Air Force Base, Arizona
(Page I of 3)
.ocelnn
ST-2S
ST-2S
Sample
Number
D2001
02002 (dup)
Sample
Dale
7/24/95
7/24/95
Matrix
SOIL
SOIL
Tnl
Group
VOC
VOC
Beg*
Depm
k
3.75
3.75
End
Depttl
II
4.25
425
Parameter
Reid*
Concentration
AIRFIELD USTi. ST-25
METHYLENE CHLORIDE
METMYLENE CHLORIDE
2
3
2
3
Qualifier
J
J
Detection
Limit
It
11
Una
MBTkg
ug/kg
Soil
HBGL
180.000
180.000
Soil Reiid
PRO
11.000
11.000
Water
HBGL
eg/I
Water Reid
PPG
pg/L
PAINT SHOP LEACH FIELD. WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
WP-27
D2003
02003
D2003
O20O3
D2003
D2003
D2003
02003
D2003
D2004(dup)
02004 (dup)
02004 (dup)
02004 (dup)
O2004(dup)
02004 (dup)
02005
D200S
D2OOS
02005
O20O5
D2005
D200S
02005
7/21/95
7/21/95
7/21/B5
7/2t/B5
7/21/BS
7/21/95
7/21/95
7/21/B5
7/21/B5
7/21/95
7/21/95
7/21/95
7/21/85
7/21/95
7/21/95
7/21/95
7/21/95
7/21/BS
7/21/BS
7/21/BS
7/21/95
7/21/95
7/21/95
SOIL
SOIL
SOU.
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOU.
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
3
3
3
3
3
3
3
3
3
45
45
45
45
45
45
5
5
5
5
5
5
5
5
3.5
35
35
3.5
3.5
3.5
35
3.5
35
5
5
5
5
5
5
55
55
5.5
55
55
55
55
5.5
ARSENIC
BERYLLIUM
CADMIUM
CHROMIUM
COPPER
LEAD
MCKEL
THALLIUM
ZINC
ARSENIC
CHROMIUM
COPPER
LEAD
NICKEL
ZINC
ARSENIC
BERYLLIUM
CHROMIUM
COPPER
LEAD
NICKEL
SELENIUM
ZINC
7.70
049
1.60
25.20
61.10
1830
2950
1.00
14900
5.90
2390
3250
1620
16.00
6650
960
0.43
2460
4810
16.50
21.60
086
12200
7.7
0.49
1.8
252
61 1
183
29.5
1
149
59
23.9
32.5
182
18
665
96
043
24.6
48.1
1B.5
216
066
122
J
J
J
J
J
J
0.72
0.24
1.2
1.9
1.4
048
4.5
0.72
095
0.7
19
14
047
4.4
0.93
07
023
1 9
1 4
047
44
0.7
094
mg/Vo
mg/kg
mg/kg
mg/kg
rug/kg
mg*g
mg*g
mgAg
mg/kg
mg/kg
mg/kg
mo/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
091
032
58
580
4 SCO
400
2.300
82
35.000
091
580
4.300
4OO
2.300
35.000
091
032
580
4.300
400
2.300
580
35.000
032
0.14
38
210
2.800
400
1.500
NIA
23.000
032
210
2.800
400
1.500
23.000
032
014
210
2.600
400
1.500
380
23.000
PRIME BEEF YARD. SS-29
SS29
SS-29
SS29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS29
SS29
02006
02006
O2006
D2006
D2006
D2006
02000
O2006
02006
02006
02008
7/26/B5
7/26/95
7/3695
7/26/95
7/26/95
7/26/95
7/2S/95
7/2645
7/26/95
7/26/95
7/26*5
SOIL
SOIL
SOIL
SOIL
SOIL
SOU
SOIL
SOIL
SOIL
SOIL
SOIL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
VOC
METAL
3
3
3
3
3
3
3
3
3
3
3
35
35
35
35
35
35
35
35
35
35
35
ARSENIC
BERYLLIUM
CHROMIUM
COPPER
LEAD
NICKEL
SELENIUM
THALLIUM
ZINC
METMYLENE CHLORIDE
ARSENIC
520
078
2960
15500
2140
29 10
1 70
1 10
23200
4
630
52
078
296
155
21 4
291
1 7
1 1
232
4
63
J
J
J
J
J
J
068
023
1 8
1 4
046
43
068
068
091
11
066
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
uo/Vg
mg/Vg
091
032
580
4 300
400
2300
580
82
35.000
180000
091
032
0 14
210
2.800
400
1.500
380
NIA
23.000
11.000
032
-------
Table 2-4
Summary of Detected Compounds
OU-5 Remedial Investigation
Williams Air Force Base, Arizona
(Page 2 of 3)
.oc*tkxi
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
SS-29
S«nipl(
Number
02008
ojooe
O2008
D2008
02008
D2008
D2008
D2009
D2009
D2009
02009
02009
02009
02009
D2009
Stmple
Oat*
7/26/95
7/26*5
7/26*5
7/26*5
7/26/95
7/26/95
7/26/94
7/26/95
7/26*5
7/26/95
7/26/9$
7/26/95
7/26/95
7/26/9$
7/26*5
Matrix
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
T*8t
Group
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
BOG*
Depth
ft
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
End
D*|Xt>
It
35
3.5
3.$
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
35
Parameter
BERYLLIUM
CHROMIUM
COPPER
LEAD
NICKEL
SELENIUM
ZINC
ARSENIC
BERYLLIUM
CHROMIUM
COPPER
LEAD
NICKEL
THALLIUM
ZINC
Raiut
0.58
35.20
79.50
22.60
30.10
090
164.00
5.20
058
26.10
102.00
20.90
24.40
0.92
200.00
Conc^ntrition
0.58
35.2
79.5
226
30.1
0.9
164
5.2
058
28.1
102
20.8
24.4
0.92
200
Qualifier
J
J
J
J
J
J
J
Detection
Limit
0.22
1.8
1.3
0.44
4.2
0.66
0.88
0.69
0.23
1.6
1.4
0.46
4.4
0.69
0.92
Unit
mg/kg
mg/kg
mg/kg
mgftg
mg/kg
mpAg^
mg/kg
mg/Vg
mg/kg
mg/kg
mo/kg
mgfcg
mg/Vg
moAg
mfl/kO
So*
HBGL
0.32
560
4.300
400
2.300
580
35.000
0.91
0.32
560
4.300
400
2.300
8.2
35.000
Soil Read
PRO
0.14
210
2,600
400
1.500
380
23.000
0.32
0.14
210
2.800
400
1,500
NIA
23,000
Water
HBGL
|ipA
Water Resid
PPG
M9/L
MUNITIONS INCINERATOR. FACILITY 1119, SS-34
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
INCI
D2014
02014
D2014
02014
02014
02014
D2014
O2014
02015
D201S
D201S
0201$
02015
02015
02015
D201S
02015
7/20*5
7/20/95
7/20/95
7/20*5
7/20*5
7/20*5
7/20*$
7/20*5
7/20/95
7/20*5
7/20*5
7/20*5
7/20*5
7/20*5
7/20*5
7/20*$
7/20*5
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
SOIL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
METAL
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3.5
3.5
3.5
3.5
3.$
3.5
3.5
3.5
3.5
35
3.5
3.5
3.5
3.5
3.5
35
3.5
ARSENIC
CHROMIUM
COPPER
LEAD
NICKEL
SELENIUM
THALLIUM
ZINC
ARSENIC
BERYLLIUM
CHROMIUM
COPPER
LEAD
NICKEL
SELENIUM
THALLIUM
ZINC
580
22.10
28.50
16.70
18.60
1.50
1.50
84.80
5.30
0.65
2390
32.40
16.60
21.50
0.86
0.99
78.80
S.B
221
28.5
16.7
18.8
1.5
1.5
64.8
53
0.65
239
32.4
166
21.5
0.66
0.99
788
J
J
J
J
1
J
0.63
1.7
1.3
0.42
4
063
0.63
0.84
0.64
0.21
1.7
1.3
0.43
4
0.64
064
085
mg/Vfl
mg/kg
mg/tig
mg/kg
mg/kg
mgAg
mg/kg
mg/kg
moAg
mg/kg
mgAg
mg/kg
nig/kg
mg/kg
mg/kg
mg/kg
mo/kg
0.91
580
4.300
400
2.300
580
8.2
35.000
0.91
0.32
560
4,300
400
2.300
560
82
35.000
032
210
2.800
400
1.500
380
NIA
23.000
0.32
0.14
210
2.800
400
1.500
380
NIA
23.000
CONCRETE HAROFIU AREA. LF-26
LF-26
LF-26
02016
O2016
7/20*5
7/20*5
SOIL
SOIL
PESTPCB
PESTPCB
3
3
35
3.5
4.4-.DD6
DwUrin
1.1
12
1.1
12
J
3.5
3.5
MS/kg
(JS/kg
4.000
90
1.300
28
-------
Table 2-4
Summary of Detected Compounds
OU-5 Remedial Investigation
Williams Air Force Base, Arizona
(Page 3 of 3)
Location
Sample
Number
Sample
Date
Matrix
T«tt
Group
Begin
Depth
fl
End
Depth
A
Parameter
R*»u»
Concentration
Qualifier
Detection
Unit
Unit
Soil
HBGL
Soil ReskJ
PRG
Water
HBGL
MffA
Water Resid
PPG
MffA
AIR FIELD USTS. ST-2S
Method Blank
Eqp. Blank
Trip Bis/*
O3001
O3002
w^w3
7/74/K
7/24/85
7/2*55
WATER
WATER
WATER
VOC
VOC
VOC
0
0
0
0
0
0
ACETONE
ACETONE
ACETONE
t
e
2
6
e
2
JB
JB
JB
10
10
10
ug/L
van.
von.
700
700
700
610
6'0
610
PAINT SHOP LEACH FIELD. WP-27
Method Blank
Eqp. Blank
O3004
O300S
7/21/BS
7/21/9S
WATER
WATER
METAL
METAL
0
0
0
0
ZINC
ZINC
t
80
9
80
B
4
4
MOA
USA
2100
2100
11000
11000
WASTE PROFILE SAMPLE
Trip Blank
O3009
7/2SV9S I WATER I VOC
0
0
METHVLENE CHLORIDE
2.1
2.1
1 poA
4.7
4.3
NOTES: Oof Course Maintenance Area samples D2010 and O2011 were nondelects; Building 1070 was not sampled (see Section 38)
J - Value is between detection limit and reporting emit. Value is estimated.
B-
MA » No Information available.
-------
FllfNAMt 40988lfSv554 137 FEB 11. 1997 OLB
SIAR1INC DATE: 01/06/95
DRAWN BY OACUILAR
DATE LAST REV : 2/11/97
DRAWN BY DBILLINGSLEY
ORAFI. CHCK. BY: C IUMLIN
ENCR CHCK BY D FREER
INITIATOR: 0 FREER
PROJ MCR W CARTER
OWC NO : 4098BIES
PROJ NO 409881
MANHOLE
(ELECK
FORMER LOCATION
OF 55 GAL. DRUM
MANHOLE
(ELEC.)
DIRT/CRASS
LEGEND:
METAL
PLATE
G
DRUM EXCAVATION AREA
(3 FEET X 3 FEET). EXCAVATED TO 45" BCS.
CONFIRMATION SAMPLES 02001 8. D2002
COLLECTED FROM BOTTOM OF EXCAVATION.
FIGURE 2-4
160 FEET
SOIL REMOVAL AND SAMPLE
LOCATIONS AIRFIELD USTs (ST-25)
WILLIAMS AIR FORCE BASE
PHOENIX. ARIZONA
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
were collected at the area using an EG&G 822-L cesium vapor magnetometer and a Geonics EM-
31 DL Terrain Conductivity Meter.
Analysis of the geophysical survey results indicated that no USTs were present at the Airfield
USTs area. The suspected vent or fill hole was identified as a light pole that had been cut off
near ground level. However, one 55-gallon drum was confirmed to have been buried upright at
the location of the suspected manway, and above an underlying storm drain line. The soil inside
this drum was removed and the presence of a bottom to the drum was confirmed; however, no
environmental samples were collected. There was no visible indication of contamination in the
soil, and the soil was returned to the drum.
The Airfield USTs location was not recommended for further investigation in the E/A. However,
the drum and soil removal action was recommended to verify the removal and/or absence of
contaminants.
Removal Action. The removal of the drum and contaminated soil was completed in ac-
cordance with an approved work plan. An area approximately 3 by 3 feet was excavated to a
depth of 45 inches. The drum and soil was removed.
Two samples were collected from the bottom of the excavation at 45 inches below ground
surface (bgs) and analyzed for total petroleum hydrocarbon (TPH) as jet petroleum grade 4 (JP-
4), volatile organic compounds (VOC), and semivolatile organic compounds (SVOC). The
analyses were performed to verify that no contaminants remained that would be hazardous to
human health or the environment. The excavation was backfilled with clean soil.
Postremoval Analytical Samples and Results. The only constituent detected at ST-25
was methylene chloride, which was in one of the two samples taken. The maximum estimated
concentration was 3 micrograms per kilogram (ug/kg). Because methylene chloride is a
laboratory reagent, this can be explained as a laboratory contaminant. Even if it were not
attributed to the laboratory, the concentration is below both the Arizona HBGL and Region IX
residential PRG levels. The removal action was adequate. This site, therefore, requires no
further action because it poses no risk to human health or the environment.
KN/3739/3739.TXT/8-29-97<:5lpm)\F/E(2-lJ-97) 2-11
-------
2.2.2.2 Paint Shop Leach Field (WP-27)
Site Description and History. The Paint Shop Leach Field area was located in the central
part of the Base, south of A Street, north of Adams Street, west of 5th Street, and east of 11 th
Street (Figure 2-3). The paint shop (Building 771) facility was constructed in 1984 and was used
for mixing and storing paints. The leach field (8 by 12 feet) shown beside Building 771 (Figure
2-5) was reportedly used to dispose of excess and waste paint. Latex paint was reportedly the
primary liquid disposed of in the leach field. Base personnel reportedly would carry paint
brushes and rollers to be cleaned to the sink location to be washed. The sink contents drained to
the leach field through a polyvinyl chloride (PVC) pipe. The leach field was comprised of a 2- to
3-foot-thick rock bed on top of soil.
Investigations. During the investigation as part of the E/A, the rock leach bed that was
overlying the area was removed, and environmental and quality assurance/quality control
(QA/QC) samples of the underlying soil were collected to determine the degree of contamination
(FT, 1994c). The surface gravel was also sampled. The excavated materials were properly
disposed. The excavated area was then backfilled with clean soil and compacted.
Four soil samples plus one duplicate were collected and analyzed for VOCs, SVOCs, TPH, and
priority pollutant metals (PPM).
Di-n-butyl phthalate was detected at a level below both the Arizona HBGL and EPA Region DC
residential PRO. The level of TPH (135 milligrams per kilogram [mg/kg]) exceeded the Arizona
UST regulatory guideline of 100 mg/kg at that time. Current ADEQ LIST regulatory level for
TPH is 7,000 mg/kg.
Analytical results for PPMs from the Paint Shop Leach Field area were also compared with the
Base-specific background ranges. Arsenic exceeded its Base-specific background range at
locations 01 and 06 (Figure 2-5), and was less than the Base-specific background range at
locations 02,03,04, and 05. Beryllium exceeded the Base-specific background range at all
locations except 06, where it was not detected. Chromium and nickel were detected at con-
centrations exceeding their respective Base-specific background ranges at locations 01,02,04,
and 05, but were within or less than their respective Base-specific background ranges at locations
03 and 06. Lead exceeded the Base-specific background range at location 01, but was within this
range at locations 02 through 06. Mercury was detected at location 05 only, where it exceeded its
KN/3739O739.TXT«-29-97<:5lpm)VF/E(2.|J-97)
2-12
-------
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NOTES:
1. SAMPLE LOCATIONS WERE APPROXIMATELY
4 FEET FROM THE 4" VERTICAL PIPE.
FINAL LOCATIONS TO BE FIELD DETERMINED
AND DOCUMENTED.
2. SAMPLE DEPTHS SHOWN ABOVE.
3. SAMPLE NUMBERS 0771-BHA-OOOOX.
FIGURE 2-5
SITE LOCATION MAP
FORMER PAINT SHOP, BLDG. 771
LEACH FIELD, (WP-27)
WILLIAMS AIR FORCE BASE
PHOENIX ARIZONA
m INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
Base-specific background range. At all six locations, zinc exceeded its Base-specific background
range.
Arsenic exceeded its EPA Region DC residential PRO, as well as the Arizona HBGL, at all
locations. Beryllium was consistently detected at levels exceeding both the EPA Region EX
residential PRG and the Arizona HBGL. All other PPMs detected were at levels less than both
the EPA Region DC residential PRG and the Arizona HBGL.
It was recommended that the leach field be excavated and samples collected from the excavated
area to confirm removal of metals and organic compounds of concern.
Removal Actions. The removal of the contaminated soil was completed in accordance with
an approved work plan. An area 14 by 30 feet was excavated to a depth of approximately 4.5
feet. The area excavated included the removal of a remaining section of drain pipe, gravel, and
plastic sheeting not removed during the previous excavation activities. Quantities of dried latex
paint were observed in the vicinity of the drain pipe.
Three soil samples were collected. The samples were analyzed for SVOCs, TPH, and PPM to
verify that no contamination remained that would be hazardous to human health or the en-
vironment. Subsequently, clean fill was placed in the excavation and compacted.
Postremoval Analytical Samples and Results. Nine metals were detected in each of the
three samples at this site (Figure 2-6). Of these metals, however, only arsenic and beryllium
exceeded the Arizona residential HBGLs and Region DC residential PRG levels. The maximum
arsenic concentration was 9.6 mg/kg at a depth of 5 feet in sample D2005. This declined to 7.70
mg/kg at 3.5 feet in sample D2003. Beryllium was at 0.43 mg/kg in sample D2005 and 0.49
mg/kg in sample D2003. Each was also greater than the background level for these metals. A
screening level risk assessment (SLRA) was performed to estimate health impacts of these results
to determine if further action is required at this site. Chapter 4.0 describes the risk assessment,
which concludes that this site poses no unacceptable risks to human health or the environment.
2.2.2.3 Sewage Sludge Trenches (DP-28)
Site Description and History. The Sewage Sludge Trenches area is located east and south of
the Base wastewater treatment plant (WWTP) on the southwest corner of the Base, just south of
KN/3739tt739.TXT/8-29-97(:51pm)\F/E<2-lJ-97)
2-13
-------
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BUILDING 771
SECURITY FENCE
5
a.
cr
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r
COVERED CONCRETE PAD-
AREA OF
EVACUATION
AVERAGE DEPTH
4.5 FT.
LOCATION OF
PERFORATED
PVC PIPE
(FRENCH DRAIN)
IN GRAVEL BED
AT A DEPTH OF
2.5 FEET
FIGURE 2-6
LEGEND:
SOIL SAMPLE LOCATIONS. D2005
COLLECTED AT 60" BCS;02003
AND D2004 COLLECTED AT 55" BCS
FENCE
AREA OF EXCAVATION
20 FEET
SOIL REMOVAL AND
SAMPLE LOCATIONS
FORMER PAINT SHOP BLDG. 77
LEACH FIELD, (WP-27)
WILLIAMS AIR FORCE BASE
PHOENIX, ARIZONA
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
Perimeter Road (Figure 2-3). Information obtained from visual inspection and aerial photo-
graphs indicate that the trench area consists of three trenches ranging in length from approx-
imately 140 to 350 feet, and 40 to 50 feet wide (Figure 2-7). According to the Phase I records
search, the WWTP digesters were out of service from 1973 to 1979, and undigested sludge was
directed to the trenches adjacent to the plant. In 1976, the Base removed sludge collected since
1973 from the trenches and disposed of it in the Landfill. In 1979, when the digesters were
reactivated, the undigested sludge collected from 1976 to 1979 was also buried in the trenches.
Investigations. On September 20, 1993, soil samples were collected from a depth of 10 to 20
inches at each of the six sample locations indicated in Figure 2-5. Soil samples were analyzed
for SVOCs, pesticides/polychlorinated biphenyls (PCB), and PPMs.
Analytical results for PPMs from the Sewage Sludge Trenches area were compared with the
Base-specific background ranges. Arsenic was detected at locations 20-01, 20-02, and 20-05
(Figure 2-7) at levels exceeding its EPA Region IX residential PRO value; however, only one
detection exceeded the Base-specific background range. Beryllium was detected at all six
locations exceeding its EPA Region DC residential PRG; however, these detections occurred at
levels less than Base-specific background.: All other PPMs detected in the Sewage Sludge
Trench samples exceeded Base-specific background, but were less than their EPA Region DC
residential PRGs or HBGLs.
Dieldrin was detected exceeding both the HBGL and the EPA Region DC residential PRG at
locations 20-01, 20-02, and 20-04. At locations 20-03, 20-05, and 20-06, dieldrin was detected
exceeding the EPA Region DC residential PRG but less than the HBGL. All other pesticides
reported were at levels less than both the HBGL and EPA Region DC residential PRG guidance
levels. Six PAH SVOCs (benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]-
fluoranthene, benzo[g,h,i]perylenet and chrysene) were detected at 20-06. Benzo(a)pyrene was
detected at concentrations greater than its Region DC residential PRG, but less than its HBGL.
All other PAHs detected were less than the Region DC residential PRG and HBGL levels.
Removal Actions. Because the Sewage Sludge Trenches are contiguous to and west of the
landfill and the contaminant (dieldrin) was common to both the Sewage Sludge Trenches and
landfill, it was determined that both sites could be remediated using the same remedy (IT,
1995c). The capping remedy had been approved in OU-1 for the landfill and was close to
implementation. The Sewage Sludge Trenches therefore were capped as part of the final remedy
KN/3739/3739.TXT«-29-97(:5lpm)\F/E(2-13-97)
2-14
-------
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WASTE TREATMENT
TANK
BUILDING
1044
DIRT ROAD
WASTE WATER
TREATMENT FACILITY
0LF01-W-07
TRENCH 3
LANDFILL
(LF-04)
200 FEET
LEGEND:
FIGURE 2-7
FENCE
SOIL SAMPLE
LOCATIONS 9/20/93
TRENCH
MONITORING WELL
SITE LOCATION MAP SEWAGE
SLUDGE TRENCHES (DP-28)
WILLIAMS AIR FORCE BASE
PHOENIX. ARIZONA
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
for the Landfill (LF-04) under OU-1. No further action is required under OU-5. The capping
action is further discussed in the BSD.
2.2.2.4 Prime Beef Yard (SS-29)
Site Description and History. The Prime Beef Yard is located in the central portion of the
Base, east of 11th Street, west of 5th Street, north of Adams Street, and just south of A Street
(Figure 2-3). This storage yard was used by the Base for storage of construction materials.
Although listed as the storage facility in the Base's Resource Conservation and Recovery Act
(RCRA) Part A Permit, it was never used for this purpose. Low levels of constituents were
detected during the E/A investigation. Based on this fact, agreements were made by the EPA,
ADEQ, and ADWR that the Prime Beef Yard would be investigated under OU-5, with removal
actions as necessary prior to sampling to verify that there are no residual contaminants at this site
that constitute a hazard to human health and the environment. The site will be formally closed,
however, under a RCRA closure plan. RCRA is applicable to no other sites in OU-5.
A temporary building in the area built on a monolithic concrete pad was used for storage of PCB-
contaminated transformers until they could be disposed of by the Base. No spills or releases
were documented from the transformer storage building.
Because full characterization is required by ADEQ to close the area, the RCRA section of ADEQ
agreed to consider the investigation completed under CERCLA and give final closure approval
under RCRA. Further investigation of the temporary building for PCB contamination and one
stained area in the northwest corner of the surrounding fenced yard for TPH contamination was
accomplished during the E/A (IT, 1994c).
Investigations. Soil samples were collected at nine locations as indicated in Figure 2-8. Soil
samples from locations 26-01 through 26-08 were analyzed for PCB/pesticides, and the soil
sample from location 26-09 was analyzed for TPH.
All detections of dieldrin, dichlorodiphenyldichloroethene (DDE), dichlorodiphenyltrichloro-
ethane (DDT), and beta-hexachlorocyclohexane (BHC) were at concentrations lower than their
respective Arizona HBGL and EPA residential PRG guidelines. The PCB Aroclor-1260 was
detected at sample locations 26-01 through 26-05 and 26-08 (Figure 2-6) at or greater than both
the HBGL of 0.18 mg/kg and the residential PRG of 0.11 mg/kg. Concentrations of Aroclor-
1260 at locations 26-06 and 26-07 were at levels between the HBGL and the residential PRG.
KN/3739/3739 TXT/8-29-97< :51 pm)\F/E<2-1J-97)
2-15
-------
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FIGURE 2-8
SOIL SAMPLE LOCATIONS 10/05/93
FENCE
SITE LOCATION MAP
FACILITY 766 PRIME BEEF
YARD (SS-29)
20 FEET
WILLIAMS AIR FORCE BASE
PHOENIX. ARIZONA
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
TPH as diesel was estimated at 46,000 mg/kg at sample location 26-09, greater than the Arizona
UST regulatory guideline for TPH at that time (100 mg/kg). The current Arizona UST regulatory
level for TPH is 7,000 mg/kg.
A removal action was recommended to excavate the soil northwest of Building 766 and the soils
surrounding the concrete pad at Building 766 and sample the soil at both locations.
Removal Actions. The removal action included the excavation of the stained soil approx-
imately 18 feet northwest of Building 766 and excavation of soils surrounding the concrete pad at
Building 766. The contaminated soil was removed in accordance with an approved work plan.
The first area to be excavated was northwest of the building; the area measured approximately 4
by 4 feet, and was excavated to a depth of approximately 3 feet. One confirmatory soil sample
was collected from the bottom of the excavation at 3 feet bgs and analyzed for TPH, VOCs,
SVOCs, and PPM to verify the absence of contamination. The second area excavated was a 30-
inch-wide section of soil from all four sides of the concrete pad to a depth of 2 feet around
Building 766. All excavated soil from the Prime Beef Yard removal action was placed in one
roll-off bin. Three undisturbed, confirmatory soil samples were collected from the excavated
area around Building 766 and analyzed for TPH, VOCs, SVOCs, PPM, and pesticides/PCBs to
verify that no contamination remained that would be hazardous to human health or the environ-
ment. Also, a composite waste profile sample was collected from the excavated material in the
roll-off bin. Subsequently, clean fill was placed in the excavations and compacted.
The site was to be considered for final closure under RCRA with the state of Arizona. The final
RCRA closure report was issued May 15, 1996.
Postremoval Analytical Samples and Results. Nine metals were detected in the four
samples (D2006, D2007, D2008, and D2009) at this site (Figure 2-9). Three of the samples were
near Building 766 and the fourth was near the area of a suspected TPH spill. Of these metals,
however, only arsenic and beryllium exceeded the Base background range for these metals and
also exceeded the Arizona HBGL and Region DC residential PRO levels. The maximum arsenic
concentration was 6.3 mg/kg at a depth of 3.5 feet in sample D2008, and 5.2 mg/kg in samples
D2006 and D2009. Beryllium was detected at 0.78 mg/kg in sample D2006 and 0.58 mg/kg in
samples D2008 and D2009. Methylene chloride was detected at an estimated concentration of 4
Mg/kg in sample D2006. This was well below either the Arizona HBGL and Region DC
residential PRG levels. An SLRA was performed to estimate health impacts of these results to
determine if further action is required at this site. The actions under this closure eliminated any
KN/3739/3739.TXT«-29-97<:51 pm)VF/E<2-13-97) 2-16
-------
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-------
unacceptable risks to human health and the environment. Chapter 4.0 describes the risk
assessment.
2.2.2.5 Golf Course Maintenance Area (SS-31)
Site Description and History. The Golf Course Maintenance Area is located adjacent to the
golf course driving range on the west side of the Base, north and west of E Street (Figure 2-3).
The area is used to park, maintain, and refuel mowers, tractors, and other vehicles for the golf
course.
The area consists of two ASTs on a concrete pad in the southeast corner of the yard, an area of
soil approximately 15 by 5 feet where the ASTs were formerly located to the north, and an area
to the east of Building 255 near the entrance gate. One AST contained diesel fuel and one
contained unleaded gasoline. Base personnel have verified the former AST location, and
observed the relocation of the ASTs from the stained soil area at the north end of the yard to the
concrete pad at the south end of the yard.
An additional area of stained soil exists adjacent to the concrete pad area near the location of one
of the ASTs. No evidence of spillage exists at the former AST location; however, the surface
where ASTs were located is disturbed and ADEQ personnel indicated evidence of a stained area
slightly south of the disturbed soil. A potentially stained area (dark soil) to the east of Building
255 near the entrance gate was sampled at a location indicated by ADEQ personnel.
Investigations. Samples were collected from five locations indicated in Figure 2-10. Samples
collected from the current and former AST locations were analyzed for TPH. Samples collected
from the potentially stained soils east of Building 255 were analyzed for S VOCs.
TPH was detected at 260 mg/kg at location 30-01 (Figure 2-7), greater than the Arizona UST
regulatory guideline of 100 mg/kg at that time. Current Arizona UST regulatory level for TPH is
7,000 mg/kg. All other detected analyses (TPH and SVOCs) in samples collected at the Golf
Course Maintenance Area were at concentrations less than Arizona HBGL and EPA Region IX
residential PRG guidelines.
A removal action was recommended to excavate soil located adjacent to the concrete pad on the
north side of the current AST locations and collect confirmatory soil samples.
KN/3739/3739.TXT/8-29-97(:51pn»\F/E(2-l3-97)
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INTERNATIONAL
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-------
Removal Actions. The removal action included the excavation of contaminated soil located
adjacent to the concrete pad (Figure 2-7) on the north side of the current AST locations (the
stained area) and the collection of two confirmatory soil samples from the bottom of the
excavated area. Contaminated soil was removed in accordance with an approved work plan. An
area approximately 2.5 by 12 feet was excavated to a depth of approximately 3 feet.
Two undisturbed, confirmatory soil samples were collected at 3.5 feet bgs and analyzed for TPH
and SVOCs to verify that no contamination remained that would be hazardous to human health
or the environment. Subsequently, clean fill was placed in the excavation and compacted.
Postremoval Analytical Samples and Results. Two samples were taken at this area, as
shown in Figure 2-11, but no contaminants were detected. Therefore, no further action is
required.
2.2.2.6 Building 1070(85-32)
Site Description and History. This facility, consisting of offices as well as a storage yard
behind the building, was constructed in 1987 to house the contractors providing refuse service on
Base. The yard is used for storage of equipment and vehicles.
Investigations. Some staining was noted in a slightly depressed area in the gravel parking area
north of Building 1070. No previous sampling has been performed at this site (Figure 2-12).
A removal action was recommended to excavate the gravel and underlying soil where staining
was noted.
Removal Actions. The removal action in the OU-5 work plan required removing the gravel
and underlying soil in an area near Building 1070 (Figure 2-12). Soil staining was previously
observed in the gravel parking area. Collection of two samples was planned for this site. There
were no previously reported activities involving the use, handling, or disposal at or near this
facility. The stained area was presumed to be oil drippings from a vehicle or other equipment.
However, during the site inspection prior to excavation, no staining was observed. The stain was
probably attributable to a rainfall event collecting at a low spot in the area prior to the site
observation. Once the rain soaked into the ground or evaporated, there was no stain. On July 19,
1995, during a Technical Working Group (TWO) meeting, the TWO members inspected the site
KN/3739/3739.TXT«-29-97<:51 pm)\F/E(2-13-97)
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and could not detect any staining nor evidence of the cited potentially contaminated area. There
was agreement of all members that no action was necessary. This agreement was formalized in a
field variance. Thus, no excavation/sampling was required or done at this site.
2.2.2.7 Munitions Incinerator (Facility 1119, SS-34)
Site Description and History. The Munitions Incinerator area is located on the eastern side
of the Base, west of Perimeter Road, northeast of Runway 12L-30R, and south of the Concrete
Hardfill Area (Figure 2-2). The facility began operating in 1979, but is no longer in use. Visual
inspection of the area revealed dark stained soil immediately to the south and east of the incin-
erator. In addition, an aboveground, 2-inch-diameter fuel line was observed leading from the
incinerator to the north, where it disappeared into the ground. Approximately 110 feet north
(adjacent to the flagpole) is a small concrete-bermed area with a pipe protruding from the ground
in the south end.
Investigations. Sampling was performed during the E/A (IT, 1994c) to determine if any
contamination existed in the soil around the munitions incinerator. Also, the bermed area
adjacent to the flagpole was excavated to verify that a UST for fueling the incinerator was not
present.
Samples were collected from three locations indicated in Figure 2-13 and were analyzed for
PPMs, SVOCs, and TPH.
One SVOC, phenanthrene, was detected in soil samples from this area at an estimated con-
centration that was less than the contract-required detection limit. Acceptable concentrations for
phenanthrene are not listed in the Arizona HBGL, and there is no established guideline in the
EPA Region DC residential PRO listings.
Analytical results for PPMs from the Munitions Incinerator area were compared to Base-specific
background ranges. All of the PPMs were detected at concentrations lower than respective
HBGLs and EPA Region IX residential PRGs, except for arsenic and beryllium; both these PPMs
were within their respective Base-specific background ranges and are not considered contami-
nants. Arsenic, beryllium, chromium, and nickel were detected at both locations 6-01 and 6-03
(Figure 2-13) at concentrations within or less than Base-specific background ranges for those
PPMs at the Base. Lead was detected twice, with one detection at location 6-02 exceeding Base-
specific background. Cadmium was detected at location 6-01 at a concentration greater than its
KN/3739O739.TXT/8-29-97(:5lpm)\F/E(2-l3-97) 2-19
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WILLIAMS AIR FORCE BASE
PHOENIX. ARIZONA
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
Base-specific background range. Copper and zinc were detected exceeding their Base-specific
background ranges at two locations (6-02 and 6-03). It was recommended that the stained soil be
removed and soil samples collected.
Removal Actions. The removal action included the excavation of soil from a dark stained
area located immediately to the south of the incinerator and the collection of two undisturbed soil
samples from the bottom of the excavated area.
An area of approximately 80 square feet of contaminated soil was removed to a depth of approxi-
mately 4 feet. The dark soil stain was irregular on the surface soil and was very limited in extent
beneath the surface soil.
Two confirmatory soil samples were collected and analyzed for pesticides/PCBs, PPMs, SVOCs,
and TPH to verify that no contamination remained that would be hazardous to human health or
the environment.
Clean fill was placed in the excavation and compacted. Chapter 4.0 confirms that there is no
unacceptable risk at the site.
Postremoval Analytical Samples and Results. Two samples were taken at this area, as
shown in Figure 2-14. Nine metals were detected in sample D2015 and eight metals were
detected in sample D2014. Of these metals, however, only arsenic and beryllium exceeded the
Base background range for metals and also exceeded the Arizona HBGL and Region DC
residential PRG levels. The maximum arsenic concentration was 5.8 mg/kg at a depth of 3.5 feet
in sample D2014, and 5.3 mg/kg in sample D2015. Beryllium was detected in only one sample,
D2015, at 0.65 mg/kg, also ait 3.5 feet. An SLRA was performed to estimate health impacts of
these results to determine if further action is required at this site, which concludes that this site
poses no unacceptable risks to human health or the environment. Chapter 4.0 describes the risk
assessment.
2.2.2.8 Concrete Hardfill Drum Removal Area (LF-26)
Site Description and History. The Concrete Hardfill Area is located on the northeast comer
of the Base, northeast of Perimeter Road, and south of the Base fence (Figure 2-2, Figure 2-15).
The area was designated for the disposal of concrete from the construction and destruction of
KN/3739/3739.TXT/B-29-97(.31 pn»\RE(2.13-97) 2-20
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MUNITIONS INCINERATOR
(SS-34)
WILLIAMS AIR FORCE BASE
PHOENIX, ARIZONA
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
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WILLIAMS AIR FORCE BASE
PHOENIX, ARIZONA
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runways for many years. Visual inspection of the area during the E/A (IT, 1994c) found debris
other than concrete, including vinyl asbestos tile, asbestos concrete pipe, several drums, empty
paint cans and roofing tar buckets, and other construction debris. Two soil piles wrapped in
plastic consisted of material removed from golf course ponds when they were lined. Also, a
former Base employee reported seeing drums of unknown content buried in this area.
Investigations. As indicated in Figure 2-15, a geophysical survey was conducted during the
E/A (IT, 1994c). Total field magnetic and EM conductivity data were collected at the site.
Samples were collected from nine locations indicated in Figure 2-15. Soil samples from this area
were analyzed for VOCs, S VOCs, and pesticides/PCBs. Samples of the concrete piping and
vinyl tiles were collected and analyzed for asbestos fiber content.
Three SVOCs (benzo[a]pyrene, benzo[b]fluoranthene, and dibenzo[a,h]anthracene) detected at
location 3-05 (Figure 2-15) exceeded the EPA Region EX residential PRO. Benzo(a)pyrene also
exceeded the Arizona HBGL at location 3-05. Dieldrin at location 3-05 exceeded the HBGL and
the EPA Region IX residential PRG. All other compounds detected at the Concrete Hardfill
Area were less than their respective HBGLs or EPA Region IX residential PRGs.
The investigation disclosed that the asbestos-containing material in the Concrete Hardfill Area is
nonfriable. Further investigation into nonfriable asbestos-laden tiles and concrete located within
the Concrete Hardfill Area is not required by either federal or Arizona guidance. These materials
do not appear to pose an unacceptable risk to human health or the environment, because there is
no known pathway for exposure to, or risk associated with, nonfriable asbestos in limited and
dispersed quantities over a large, outdoor area. However, it was recommended that the Concrete
Hardfill Area be included under OU-4 for further investigation upon completion of the removal
action in OU-5 to ensure there is no human health hazard.
One 55-gallon drum was observed and its contents was unknown. Therefore, it was rec-
ommended that the drum and surrounding soils and concrete be removed and soil samples
collected.
This drum removal area under OU-5 has now been designated as the Concrete Hardfill Drum
Removal Area to avoid confusion with the remainder of the Concrete Hardfill Area, which is
being investigated under OU-4.
KN/3739/3739.TXT/8-29-97051 pm)\F/E(2-13-97)
2-21
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Removal Actions. The removal action included the 55-gallon drum, surrounding soils and
concrete located in the surface drainage ditch, and the collection of confirmatory soil samples
from the bottom of the excavated area in accordance with the approved work plan.
The removal of the drum, surrounding contaminated soil, and concrete was completed in an area
2.5 by 3 feet excavated to a depth of 3 feet.
Two undisturbed soil samples were collected from the bottom of the excavation and analyzed for
SVOCs and pesticides/PCBs to verify that no contamination remained that would be hazardous
to human health or the environment.
Clean fill was placed in the excavation and compacted. Chapter 4.0 confirms that there is no
unacceptable risk at the site.
Postremoval Analytical Samples and Results. One sample was taken at this site, as
shown in Figure 2-16. Low levels of the pesticides 4,4-DDE (1.1 ug/kg) and dieldrin (12 ug/kg)
were detected in the sample. Both were well below the Arizona HBGL and Region IX
residential PRO levels. An SLRA was performed to estimate health impacts of these results to
determine if further action is required at this site. Chapter 4.0 describes the risk assessment,
which concludes that this site poses no unacceptable risks to human health or the environment.
2.2.2.9 Sewage Sludge Stockpile Area (Area 28)
Site Description and History. The Sewage Sludge Stockpile area is located to the northeast
of the golf course (Figure 2-3) on Perimeter Road. This area was used for stockpiling treated
sludge from the WWTP from 1979 until late 1992.
Investigations. Visual inspection indicated that the sewage sludge piles have been graded
level with the ground surface to an approximate thickness of 1 to 7 inches. The work was
previously completed in September 1993 and reported in the final E/A report (IT, 1994c).
There were 5 SVOCs, 6 peslicides/PCBs, and 11 metals detected from samples taken from the
stockpile area. Due to similarities in chemicals between Area 28 and the Landfill Area (LF-04),
a comparison was made with the risk assessment results at LF-04 as reported in the OU-1
remedial investigation report addendum (IT, 1994d). This report indicated that a maximum risk
KN/3739/3739.TXTffl-29-97(:Jlpin)\F/E(2.|3-9'7) 2-22
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PREVIOUS STUDY
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PREVIOUS STUDY
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WILLIAMS AIR FORCE BASE
PHOENIX, ARIZONA
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
from dieldrin in soil was 5.8 x 10"6, which is within the acceptable EPA level of 10"6 to 10"*.
Thus, dieldrin did not pose an unacceptable risk to human health or the environment.
Removal Actions. Although no further action was required at Area 28, the Sewage Sludge
Stockpile was removed in January 1996 to eliminate its unsightliness and the material properly
disposed in an approved landfill (IT, 1996).
Because action was taken to remove the visual public nuisance, even though no further action
was required, no confirmatory samples were necessary or taken. No further remedial action is
required at this site because it poses no unacceptable risks to human health or the environment.
2.2.3 Demographics
Because of the Base size and close proximity of the nine OU-5 sites, the site-specific discussion
on the demographics is the same as previously presented in Section 2.1.1.
2.2.4 Geology
Because of the uniform nature of the Basewide geology and the fact that the nine sites included in
the OU-5 ROD are in relative close proximity, the site-specific geology is the same as the
discussion previously presented in Section 2.1.3.
2.2.5 Groundwater
Because the nine sites included in the OU-5 ROD are in relatively close proximity, the site-
specific groundwater is the same as the discussion previously presented in Section 2.1.4. Based
on the nature and concentrations of contaminants detected at the OU-5 sites, there is no reason to
suspect impact to groundwater, which is at a depth of approximately 150 feet. The actions at
OU-5 were also performed prior to promulgation of the Arizona Amended Soil Remediation
Rules (April 1966). No monitoring wells were required by the approved work plan to be
installed at any of the OU-5 sites.
2.2.5 Surface Water
The topography of the Base is essentially flat, with the surface water draining to ditches that
drain the Base. No surface water contamination was expected, so no surface water sampling was
required in the approved work plan.
KN/3739/3739.TXT«-29-97(.S I pm)\F/E<2-1J-97) 2-23
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2.2.7 Contaminant Persistence in the Environment
Chemical persistence in environmental media is determined by the chemical's ability to move
through a medium, to transfer from one medium to another, and to transform or degrade. These
processes are controlled both by the chemical or element properties and the medium. Migration
to groundwater can occur via water infiltration, dispersion, and diffusion. Sorption of chemicals
onto soil particles or soil organic matter can reduce migration; similarly, chemically or biologi-
cally mediated transformation or degradation of chemicals can reduce migration.
Inorganics. All soils contain natural trace levels of metals so that their presence in soils is not
necessarily indicative of contamination. Metals can be transformed (oxidized or reduced) so that
mobility and toxicity are affected; however, metals cannot be biologically degraded. In the soil,
the fate of metals can be found in one or more of the following (Shuman, 1991):
• Dissolved in the soil pore water
• Adsorbed on inorganic soil constituents
• Associated with insoluble soil organic matter
• Occupying exchange sites on inorganic constituents
• Precipitated as pure or mixture of solids.
Metals added to the soil react with the soil components in a variety of interrelated ways. These
reaction mechanisms can generally be classified as inorganic and organic complexation/
speciation, oxidation/reduction reactions, precipitation/dissolution reactions and adsorp-
tion/desorption reactions. The reaction mechanisms and rates both in soils and the water column
depend on the type and amount of organic matter, clay, and hydrous oxides in the soil. Other
factors include soil reaction potential (pH), exchangeable cations, oxidation/reduction potential
(Eh), soil/water composition, infiltration rate, and chemical concentration.
Organics. The mobility of organic compounds within the soil is affected by chemical processes
that are in part due to a chemical's volatility, octanol-water partition coefficient (a measure of the
affinity of a chemical to partition from water to organic materials), water solubility, and
concentration. In general, the more water insoluble a compound is, the more likely it is to adsorb
on a sediment or organic surface. For several groups of compounds (including phenols,
phthalates, and monocyclic aromatics such as benzene), volatilization, sorption, and bio-
degradation are all prominent processes. The behavior of a PAH was found to be a function of
the number of rings present. Important processes for this class of compound are sorption and
aerobic and anaerobic biodegradation. The fate of chlorinated pesticides is determined by
sorption, volatilization, and/or biotransformation.
KN/3739/3739.TXT«-29-97(:5lpm)VF/E(2-l3-97) 2-24
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2.3 Highlights of Community Participation
Ongoing Public Involvement A community relations plan for the Base was issued in
February 1991 (IT, 1991c) and updated in March 1995. This plan listed contacts and interested
parties throughout the USAF, government, and the local community. The plan also established
communication channels to ensure timely dissemination of pertinent information to the sur-
rounding community through mailings, public announcements in the local newspaper, public
meetings, public comment periods, public service announcements, and the establishment of
information repositories in local libraries.
Early in the IRP, the Base established a Technical Review Committee (TRC) to provide review
and offer comment and recommendations on the progress of the cleanup effort. The TRC
included representatives from the USAF and other governmental agencies as well as appointed
representatives from the surrounding communities. Governmental agencies represented included
EPA Region DC, ADEQ, ADWR, and the Maricopa County Department of Health.
With the advent of Base closure, the TRC was expanded to include additional community stake-
holders and is now called the Restoration Advisory Board (RAB). Much the same as a TRC, the
RAB acts as a forum for discussion and exchange of information regarding cleanup between the
installation, governmental agencies and the community. However, because the RAB provides for
an expanded and more diverse membership representing the community, a greater opportunity is
afforded to those directly affected by the cleanup process to participate and provide input. This
input will be especially valuable as decisions are made regarding transfer and end uses of Base
property.
An administrative record that contains the documents relating to investigation and cleanup
activities proposed for the Base has been established and is available for public inspection as pan
of the information repositories at the Gilbert Public Library, Gilbert, Arizona and the Base
Conversion Agency (Williams AFB), Mesa, Arizona.
Public Involvement Specific To OU-5. The public has been notified of intended actions at
OU-5 as part of public meetings for OU-3 and OU-2 amendment. The proposed plan for OU-5
was issued in January 1997. A public meeting was held on January 7, 1997, the details of which
are provided in the responsiveness summary chapter (Chapter 7.0).
KN/3739/3739.TXT/8-29-97(.5lpm)\F/E(2-l3-97) 2-25
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3.0 Scope and Role
As with many Superfund sites, the environmental problems at Williams AFB are complex. As a
result, the USAF has organized the work into the following OUs.
• OU-1 addresses soil and groundwater contamination at the following ten sites:
- Landfill (LF-04)
- Fire Protection Training Area No. 1 (FT-03)
- Northwest Drainage System (SD-10)
- Radioactive Instrumentation Burial Area (RW-11)
- Pesticide Burial Area (DP-13)
- Hazardous Materials Storage Area (SS-01)
- USTs at four area (ST-05, ST-06, ST-07, ST-08).
• OU-2 addresses soil and groundwater at the Liquid Fuels Storage Area (ST-12).
Deep soil at ST-12 was added to OU-2 by an amendment.
• OU-3 addresses soil and groundwater at the following two sites:
- Fire Protection Training Area No. 2 (FT-02)
- Southwest Drainage System (SD-09) (soil only).
• OU-4 addresses investigations of contamination at 11 sites.
- Electroplating/Chemical Cleaning (Facility 1085, Site SS-16)
- Old Pesticide/Paint Shop (Facility 742, Site SS-17)
- Oil/Water Separator - Petroleum, Oil, and Lubricant (Facility 550, Site SD-18)
- Former Skeet Range at Former South Desert Village (Site SS-19)
- Firing Range/Skeet Range (Facility 927, Site SS-20)
- Facilities 1020 and 1051 (Site SS-21)
- Aboveground Storage Tanks (AST) 556 and 557 (Site ST-22)
- Building 10(59 (Site SS-23)
- Building 1010 (Site SS-24)
- Concrete Hardfill Area (Site LF-26)
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- Facility 1004 (Area 14).
• OU-5 addresses removal actions at the following nine sites:
- Airfield Underground Storage Tanks (Site ST-25)
- Paint Shop Leach Field (Site WP-27)
- Sewage Sludge Trenches (Site DP-28) (these were included in the OU-1 remedy)
- Prime Beef Yard (SS-29)
- Golf Course Maintenance Area (SS-31)
- Building 1070 (SS-32)
- Munitions Incinerator (Facility 1119, SS-34)
- Concrete Hard Drum Removal Area (LF-26)
- Sewage Sludge Stockpile Area (Area 28).
As described in Section 2.2, the remedy selected in this ROD is designed to be consistent with
any subsequent remedies and planned future actions at the Base proposed in all subsequent
RODs.
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4.0 Risk Assessment
4.1 Introduction
This section presents SLRAs on six OU-5 sites where excavation was performed to remove areas
of suspected contamination. No unacceptable risks should be present at the sites where removal
actions were performed. Nevertheless, the SLRAs were performed to determine if chemicals that
remain require remedial action to protect human health and the environment. This risk assess-
ment was performed as part of the RI initiated by the US AF under the IRP. The results of the
assessment are used to determine the need for any remedial action and to establish a time frame
to develop any required long-term alternatives. This risk assessment was conducted in accord-
ance with the guidance documents, Risk Assessment Guidance for Superfund, Human Health
Evaluation Manual, Part A, Interim Final (EPA, 1989) and Region IX Preliminary Remediation
Goals (PRG) First Half 1995 (EPA, 1995).
This section includes an SLRA on each of the following sites that are part of OU-5:
• Airfield USTs (ST-25)
• Paint Shop Leach Field (WP-27)
• Prime Beef Yard(SS-29)
• Golf Course Maintenance Area (SS-31)
• Munitions Incinerator (Facility 1119, SS-34)
• Concrete Hardfill Drum Removal Area (LF-26).
An SLRA was not performed on the Sewage Sludge Trenches Area (DP-28) because it was
included in the final remedy with LF-04 in OU-1 (Section 1.2), nor on Building 1070, where
evidence of the cited potentially contaminated area was not found (see Section 2.2.2.6). The
Sewage Sludge Stockpile Area (Area 20) was eliminated in Chapter 2.0.
The SLRAs were conducted in two phases:
• Phase 1: The environmental sampling data collected during RI activities were
reviewed and evaluated, and contaminants of potential concern (COPC) were
identified.
• Phase II: Risk characterization, which consists of estimating conservative
screening level risks for the COPCs identified in the Phase I based on methodology
suggested by EPA (1995), was performed. Sites where risks exceed the upper
bound of the acceptable cancer risk range (10") (EPA, 1990), or a noncancer hazard
index (HI) of one, will be considered for further study under OU-4 (IT, 1995b).
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Data validation procedures, summary statistics, and identification of COPCs are described in
Section 4.2. Section 4.3 presents a brief exposure assessment section outlining the exposure
scenario and exposure point concentrations. The risk characterization, Phase D of the SLRA,
methodology, and results are described in Section 4.4. Overall uncertainties associated with the
SLRAs are discussed, qualitatively, in Section 4.5. These SLRAs do not include a toxicity
assessment section and a detailed exposure assessment found in traditional baseline type risk
assessments because SLRAs use the default exposure scenario and toxicity assessments included
in EPA (1995) methodology. When their default exposure scenario is used, these sections are not
required.
4.2 Identification of Constituents of Potential Concern
Data collected during the RI were evaluated for use in the risk assessment in accordance with
EPA guidelines. This process includes evaluating the sample collection and analytical methods
used, evaluating the quality of the data, and comparing the data to EPA (1995) residential PRGs
and to background. The purpose of this selection process is to first identify those constituents
potentially harmful to human health if present at the site, then identify those constituents that are
likely to be site-related and, finally, evaluate the acceptability of the analytical data to be used in
the quantitative risk assessment (EPA, 1989).
4.2.1 Data Sources
Background. The Parties to the FFA agreed that it was necessary to establish Base-specific
background levels for inorganic constituents in the surface soil as recommended in the OU-1 RI
report (IT, 1992a). On this basis, background surface soil samples were collected and analyzed
for inorganics. The OU-3 FSP addendum (IT, 1993b), and OU-1 RI work plan addendum (IT,
1993c) specified the exact locations and techniques that were approved by the FFA Parties. Nine
surface soil samples and a duplicate were collected and the analytical results were used to
determine a Base-specific background concentration for each inorganic constituent. The
background metals that were analyzed included antimony, arsenic, beryllium, cadmium,
chromium, copper, lead, mercury, nickel, selenium, silver, thallium, and zinc.
Site-Related. At the sites listed in Section 4.1 where excavations were performed, confirma-
tory soil samples were taken at the bottom and/or limits of an excavation. After excavation and
sampling were completed, the excavated sites were backfilled with clean soil; therefore,
subsurface soils were the only medium sampled. No soil samples were taken at Building 1070 or
KN/3739/3739 TXT/8-29-97< :51 pm)\RE<2-13-97)
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DP-28 due to reasons noted in Section 4.1. Detailed analytical results for these sites are
presented in Appendix A of the OU-5 RI report (IT, 1996).
As noted in Section 1.4, it was assumed that there was no impact on groundwater, because
contamination was limited to shallow soil and confirmatory sampling has shown that there is no
contaminant source. Thus, no groundwater data were acquired.
4.2.2 Data Validation
Data validation is an after-the-fact, independent, systematic process of evaluating data and
comparing them to pre-established criteria to confirm that the data are of acceptable technical
quality. Specific criteria are reviewed to determine whether the data meet the stipulated data
quality objectives. There are five principal quality objectives:
• Precision
• Accuracy
• Completeness
• Comparability
• Representativeness.
To verify that these objectives are met, field measurements, sampling and handling procedures,
laboratory analysis and reporting, and nonconformances and discrepancies in the data are
examined to determine compliance with appropriate and applicable procedures. The procedures
and criteria for validation are: defined in the RI/FS data validation program guidelines, which are
based on the EPA national functional guidelines for data review (EPA 1988a, b).
All environmental sampling data are evaluated for suitability for use in the risk assessment.
Analytical results for constituents are reported using Contract Laboratory Program (CLP) data
qualifiers. Constituents flagged with a "U" qualifier are considered to be not detected, or
detected at a concentration below the normal, random "noise" of the analytical instrument.
Estimated quantitative results such as those identified by a "J" qualifier are used in the assess-
ment (EPA, 1989). The "J" qualifier is the most encountered data qualifier in CLP data
packages. Under the CLP, the "J" qualifier describes an estimated value when a compound is
present (spectral identification criteria are met), but at values less than the contract-required
quantitation limit, or when QC samples suggest that the sample results may be in error (e.g.,
when spike samples are outside of required limits or when holding times are slightly missed). If
validation of the data reveal that samples must be rejected (assigned an "R" qualifier), the
rejected data are not used for the SLRA.
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4.2.3 Selection of Contaminants of Potential Concern
Once the data set is complete, summary statistics on site and background analytical data sets are
compiled and source-concentrations for all the chemicals are estimated. Chemicals are then
eliminated from the list of COPC based on the following criteria as recommended by EPA
(1989):
• Frequency of Detection. Constituents were eliminated if they were detected
infrequently (5 percent or lower frequency of detection), providing there was no
evidence that infrequent detection reflected a "hot spot" location.
• Risk-Based Screening. Compare source-concentrations with EPA (1995)
residential PRGs for residential soil; chemicals are excluded from further consider-
ation if their source-concentrations are equal to or less than the residential PRGs.
• Background. If the mean of the site-influenced values were less than the mean of
the background values, the chemicals were excluded from further considerations. If
the mean of the site-influenced values were marginally greater than the background
mean, a Students t-test was performed to determine if the former is statistically
greater than the latter.
• Chemical Specificity. Analytical results that were not specific for a particular
compound (e.g., gross alpha, gross beta, TPH, etc.) were excluded from further
consideration.
4.2.4 Data Evaluation
The statistical methods used in data evaluation are discussed in this section, and reflect EPA
headquarter guidance (EPA, 1989). The summary statistic tables on site-related data for the sites
evaluated in these SLRAs are presented in the OU-5 report (IT, 1996). For each set of data used
to describe the concentration of contaminants in a medium, the following information was
tabulated in the tables:
• Frequency of detection
• Range of detection limits
• Source-concentration
• Mean concentrations
• Background mean concentrations
• Region DC residential PRGs
• COPC selection.
Because of the uncertainty associated with characterizing contamination in environmental media,
EPA (1989) recommends that the 95 percent upper confidence limit (UCL) on the mean or the
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maximum detected concentration, whichever is smaller, should be adopted as the source-
concentration. During the confirmatory sampling round, a maximum of three samples were
taken for the compounds analyzed at all the sites. Ninety-five percent UCLs could not, therefore,
be estimated, because a minimum of four samples is required to estimate UCLs. Thus, the
maximum concentrations were adopted as the source-concentrations at all the sites.
Analytical results are presented as nondetects whenever constituent concentrations in samples do
not exceed the detection or quantitation limits for the analytical procedures for those samples.
Generally, the detection limit is the lowest concentration of a constituent that can be "seen"
above the normal, random noise of an analytical instrument or method. To apply these statistical
procedures to a data set with nondetects, a concentration value must be assigned to nondetects.
In this assessment, one-half I he detection limit was assigned to the nondetects (EPA, 1989).
4.2.5 Contaminants of Potential Concern for Subsurface Soil
The COPC selected for each site are summarized in Table 4-1. COPC were selected based on the
criteria listed in Section 4.2.3. A brief description of the selection process for each site is
presented in this section, while the detailed discussions of the selection process is presented in
the OU-5 RI report (IT, 1996).
4.2.5.1 Airfield USTs (ST-25)
Methylene chloride was the only chemical detected, but its source-concentration was less than
the residential PRO; thus, no COPC were selected at this site.
4.2.5.2 Paint Shop Leach Field (WP-27)
Organics for which analyses were performed were not detected in any of the samples. Arsenic,
with a source-concentration of 9.6 mg/kg, was the only COPC selected at WP-27. Beryllium was
eliminated as a COPC because the mean site concentration for beryllium was less than its
background mean concentration.
4.2.5.3 Prime Beef Yard (SS-29)
Arsenic, with a source-concentration of 6.3 mg/kg, was the only COPC selected at SS-29.
Beryllium was eliminated as a COPC because the mean site concentration for beryllium was less
than its background mean concentration. All other inorganics were eliminated from the list of
COPC because their source-concentrations were less than their respective residential PRGs.
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Table 4-1
COPC Selected for Sites at OU-5
Williams Air Force Base, Arizona
Site
ST-23
WP-27
SS-29
SS-31
SS-34
LF-26
COPC
No COPC
Arsenic
Arsenic
No COPC selected
Arsenic
No COPC selected
Soil Concentration
(mg/kg)
NA
9.6
6.3
NA
5.8
NA
NA - Not applicable.
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Methylene chloride was the only organic compound detected, but it was excluded from the
COPC list because its source-concentration was less than the residential PRG.
4.2.5.4 Golf Course Maintenance Area (SS-31)
No constituents were detected; therefore, no COPC were selected at this site.
4.2.5.5 Munitions Incinerator (Facility 1119, SS-34)
As explained in Section 4.1.5, beryllium was not selected as a COPC and arsenic, with a source-
concentration of 5.8 mg/kg, was the only COPC selected at the Munitions Incinerator. Organics
for which analyses were performed were not detected in any of the samples.
4.2.5.6 Concrete Hardfill Drum Removal Area (LF-26)
The only compounds detected at LF-26 were 4,4,-DDE and dieldrin, but they were excluded from
the COPC list because their source-concentrations were less than the residential PRGs. Thus, no
COPCs were selected at this site.
4.3 Exposure Assessment
This section presents the default exposure assessment used to estimate PRGs (EPA, 1995). The
default exposure assessment provides a conservative screening level estimate of potential
exposures of human receptors to constituents found at the site. Exposure is defined as the
contact of a receptor with a chemical. Exposure assessment is the estimation of the magnitude,
frequency, and duration of contact for each identified route of exposure. The magnitude of an
exposure is determined by estimating the amount of chemical available at the receptor exchange
boundaries (i.e., lungs, gastrointestinal tract, or skin) during a specified time period. The general
procedure for conducting an exposure assessment is (EPA, 1989):
• Characterization of exposure setting
• Identification of potential exposure pathways
• Quantification of exposure (where possible).
4.3.1 Characterization of Exposure Setting
Section 2.1 describes the physical characteristics of the Base as well as the population, both
human and environmental, living on or near the area that may be affected by the contaminants at
the site.
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Receptor Assessment The conservative residential receptor outlined in EPA (1995) was
used for all the sites evaluated in this SLRA.
4.3.2 Identification of Potential Exposure Pathways
The default exposure pathways for the residential land-use scenario used to calculate PRGs
(EPA, 1995) are adopted for all the sites evaluated in these SLRAs. Exposure is limited to soil
only and the exposure pathways include ingestion, inhalation of particulates, and inhalation of
volatiles. As noted in Section 2.2.5, groundwater at this site is not expected to be impacted;
therefore, exposure to groundwater was not included.
4.3.3 Estimation of Exposure
This section describes the concentration estimation of individual site-related constituents of
concern that may reach human receptors. As described earlier, the exposure models and input
parameters are the default values used to calculate the PRGs (EPA, 1995) for the residential soil
exposure scenario. The source concentration is adopted as a screening level exposure-point
concentration. Hence, it is conservatively assumed that the residents are directly exposed to the
contaminated subsurface soils at all the sites.
4.4 Risk Characterization
Once COPC were identified, an evaluation was performed for each site to estimate the cancer
risk or noncancer hazard quotient (HQ) associated with each chemical in soil. Cancer risks and
noncancer HQs were calculated for the residential scenarios for the COPC retained.
PRGs based on carcinogenicity are concentrations that correspond to a risk of 10"6. Therefore,
the cancer risk associated with the source concentration was estimated as follows:
Eq. 4.1
v * ivjcj
where:
ILCR = incremental lifetime cancer risk (unitless probability)
SC = source concentration (mg/kg)
PRGC = cancer-based residential PRO (mg/kg)
10"6 = cancer risk corresponding to the residential PRG.
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Residential PRGs based on noncancer effects are concentrations that correspond to a HQ of 1.
Therefore, the HQ associated with the source concentration was estimated as follows:
5C • • - Eq. 4.2
where:
HQ = hazard quotient for noncancer effects (unitless ratio)
SC = source concentration (mg/kg)
PRGn = noncancer-based residential PRO (mg/kg)
1.0 = HQ corresponding to the residential PRO.
The individual ELCRs are summed to estimate a total cancer risk associated with exposure to the
soil at the site of interest. Similarly, the individual HQs are summed to estimate a total non-
cancer HI for the site. The results of these analyses for all the sites evaluated in OU-5 are
presented in Table 4-2.
Chemicals selected as COPCs would be evaluated for both cancer and noncancer effects if they
are known to induce both the effects. Arsenic, which was the only compound selected as a
COPC (Table 4-2), is known to induce both cancer and noncancer effects. It was selected as a
COPC because its source-concentrations exceeded its cancer residential PRG of 0.32 mg/kg, and
not its noncancer residential PRG of 22 mg/kg (EPA, 1995). It may be noted that a risk range of
10"6 to 10~* and an HI less than 1 are generally considered acceptable under the EPA guidelines
used to evaluate risk (EPA, 1989; 1990).
The site-specific risk results are discussed in the following paragraphs.
Airfield USTs (ST-2S). No COPC were identified for this site; therefore, it can be concluded
that this site poses no unacceptable risk to human health or the environment.
Paint Shop Leach Held (WP-27). Arsenic was the only COPC selected at this site. From
Table 4-2, it can be seen that the screening level risk (3 x 10"5) and HI (0.4) for arsenic are within
acceptable limits (EPA, 1989; 1990). Because the conservative estimate of risk and HI are
within an acceptable range, it is concluded that this site poses no unacceptable risk to human
health or the environment.
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Table 4-2
Summary of Risk Evaluation for Sites in OU-5
Williams Air Force Base, Arizona
Chemical
(mg/kg)
Site: Airfield USTs
No COPC present
Source-Term
Concentration
Residential
PRGs
Cancer/
Noncancer
Target
Cancer Risk
Target
Hazard Index
ST-25)
Site: Paint Shop Leach Field (WP-27)
Arsenic
9.6
3.20E-01
c
3.00E-05
NA
Site: Prime Beef yard (SS-29)
Arsenic ] 6.3
3.20E-01
c
1.97E-05
NA
Site: Golf Course Maintenance Area (SS-31)
No COPC present
Site: Munitions Incinerator
Arsenic
5.8
3.20E-01
c
1.81E-05
NA
Site: Concrete Hardfill Drum Removal Area (Portion of LF-26)
No COPC present |
,
COPC - Chemical of potential concern
PRG = Preliminary remediation goals, EPA Region IX, 1995a
c = Cancer risk
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Prime Beef Yard (SS-29). Arsenic was the only COPC selected at this site. From Table 4-2,
it can be seen that the screening level risk (2 x 10~5) and HI (0.3) for arsenic are within acceptable
limits (EPA, 1989, 1990). Given that the conservative estimate of risk and HI are within an
acceptable range, it is concluded that this site poses no unacceptable risk to human health or the
environment.
Golf Course Maintenance Area (SS-31). No COPC were identified for this site; therefore,
it can be concluded that this site poses no unacceptable risk to human health or the environment.
Munitions Incinerator (Facility 1119, SS-34). Arsenic was the only COPC selected at this
site. From Table 4-2, it can be seen that the screening level risk (1.8 x 10s) and HI (0.3) for
arsenic are within acceptable limits (EPA, 1989; 1990). Given that the conservative estimate of
risk and HI are within an acceptable range, it is concluded that this site poses no unacceptable
risk to human health or the environment.
Concrete Hardfill Drum Removal Area (LF-26). No COPC were identified for this site;
therefore, it can be concluded that this site poses no unacceptable risk to human health or the
environment.
4.5 Uncertainty Evaluation
4.5.1 Terminology
Generally, risk assessments carry two types of uncertainty. Measurement uncertainty refers to
the usual variance that accompanies scientific measurements, e.g., instrument uncertainty
(accuracy and precision) associated with constituent concentrations. The results of the risk
assessment reflect the accumulated variances of the individually measured values used to develop
it. A different kind of uncertainty, called informational uncertainty, stems from data gaps, i.e.,
the fact that additional information is needed to complete the database for the assessment. Often
the data gap is significant, such as the absence of information on the effects of human exposure
to a constituent or on the biological mechanism of action of an agent (EPA, 1992).
4.5.2 Sources of Uncertainty
As noted previously, uncertainties are associated with the information and data used in each
phase of the baseline risk assessment. Uncertainties associated with information and data are
evaluated in this section to provide a sound, balanced basis for evaluating the overall quality of
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the risk assessment results. Sources of uncertainty, as well as the direction of bias that results
(i.e., whether conservatism is increased or decreased) are presented in the following sections.
4.5.2.1 Selection and Quantification of COPC
Uncertainty associated with the selection process used to determine the COPC and estimation of
source-concentrations arises from the following:
• Surface soils were not collected from any of the sites evaluated; however, it is
believed that the nature of the contamination would be best reflected by sampling
subsurface soil because these sites were backfilled and covered with clean soil.
• Estimated summary statistics are uncertain and overconservative. For statistical
purposes, if a constituent is positively identified at a site and has at least a single
positive hit, all the samples with nondetects are assumed to have a value equal to
half the minimum detectable activity and are included in the data set. These pro-
cedures introduce a conservative bias into the risk assessment.
• Limited numbers of samples result in the calculation of wide confidence intervals
on the mean concentration and high source-concentrations. Ninety-five percent
UCLs on the mean could not be estimated at several sites due to too few samples.
Thus, the maximum concentrations were adopted as the source, introducing a
conservative bias into the risk assessment.
• Laboratory analytical techniques have a degree of uncertainty associated with them.
These uncertainties are documented by using data qualifiers to reflect the degree of
certainty of measurement. The direction of bias is unclear.
• The COPC selection was based on residential PRGs that may not reflect plausible
site-specific land use scenarios.
4.5.2.2 Exposure Point Concentrations
It was assumed that the source concentrations were also the exposure-point concentrations for the
purposes of the SLRA. However, it is unlikely that a residential receptor would be exposed to
subsurface soil. Hence, this assumption introduces a highly conservative bias into the risk
assessment.
4.5.2.3 Selection of Hypothetical Receptors and Potential Exposure Pathways
As previously noted, the selection of a residential receptor being exposed to subsurface soil
introduces a highly conservative bias into the risk assessment.
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4.5.2.4 Risk Characterization
The primary goal of this assessment was to conduct a screening level assessment. Therefore,
conservative biases exist at every phase of this assessment. These biases are additive, resulting
in overly conservative risk, or HQ, estimates.
This effort to identify potential uncertainties associated with each step of the risk assessment is
not intended to discredit the calculated results, but to point out that risks are calculated for
hypothetical receptors under a definite, strict method. Refinements of sampling plans, analytical
techniques, data statistical evaluation, exposure assessment models and parameters, hazard
evaluation, dose-response assessment, and risk characterization could reduce these uncertainties.
4.5 Risk Conclusions
No COPC were selected at LF-26, SS-31, and ST-25; the screening level target cancer risks at
WP-27, SS-29, and the munitions incinerator are within the acceptable risk range (10"* to 10"4).
In addition, no COPC were selected based on noncancer residential PRGs. Thus, it can be
concluded that the sites at OU-5 pose no unacceptable risk or hazard to human health or the
environment.
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5.0 Description of No-Action Alternative
The no-action alternative requires no further action at any of the OU-5 sites. With the
implementation of the OU-5 action memorandum, the soil with COPC identified at the sites
included in OU-5 were excavated and removed from the sites. Postremoval sampling results
confirmed that all constituents in soils at OU-5 sites are at levels that do not pose any
unacceptable risk or hazard to human health or the environment, as substantiated in Section 2.2.2
and Chapter 4.0. Therefore, no action is the only reasonable alternative.
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6.0 Documentation of Significant Changes
This section documents the reasons for any significant changes to the selected remedy after
receiving public comments on this document.
The public comment period for cleanup of soils at OU-5 was held from December 20, 1996 to
January 20, 1997. No written comments were received and there were no changes resulting from
the public comment period.
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7.0 Responsiveness Summary
7.1 Overview
The USAF published the proposed plan for a no-action alternative for OU-5, Williams AFB in
December 1996; the public comment period began December 20, 1996 and extended through
January 20, 1997. A public meeting was held at the Williams Gateway Airport, Building 1, 601
South Power Road in Mesa, Arizona to present the plan to the public on January 7, 1997. The
ROD recommends a no-action alternative for all OU-5 sites because there is no contaminant at
the sites that poses a unacceptable risk to human health and the environment.
The public meeting held on January 7, 1997 was attended by all members of the RAB and two
members of the public. There were few comments and no written questions received.
7.2 Background on Community Involvement
To date, the level of community interest and concern regarding the groundwater and soil
contamination at OU-5 in particular and environmental cleanup in general at Williams AFB can
be characterized as extremely low. In contrast, Base reuse issues have sparked great interest,
which in turn have created an indirect interest on what effect, if any, the environmental
contamination at the Base will have on future use or transfer of Base property.
The RAB has been briefed on the progress of environmental investigation all OUs and the
selected remedy identified in the ROD for OU-5. A notice was placed in the Tribune announcing
to the public that the proposed plan had been placed in the information repository at the Gilbert
Public Library and that there was an opportunity to offer input during the 30-day comment
period. A fact sheet describing the no-action remedy for cleanup of OU-5 was also placed in the
information repository and distributed at the public meeting. The notice announcing the public
comment period and the availability of the proposed plan for review contained the time, location,
and subject matter of the public meeting.
7.3 Summary of Comments Received During the Public Comment Period and
Air Force Responses
The public comment period on the proposed plan for cleanup of soils at OU-5 was held from
December 20, 1996 through January 20, 1997. No written comments were received.
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7.4 Community Relations Activities at Williams Air Force Base
Community relations activities at Williams AFB have been guided by a written community
relations plan. Design of the site-specific community relations plan was guided by the level and
types of concern expressed by local community members in one-on-one interviews conducted in
November 1989.
An information repository containing correspondence, fact sheets, and other pertinent documents,
such as the community relations plan, has been established and is currently maintained at the
Gilbert Public Library, 665 North Gilbert Road, No. 152, Gilbert, Arizona 85234, (602) 892-
3141.
A Technical Review Committee (TRC) provided review and comment on actions and proposed
actions with respect to releases and threatened releases of hazardous substances at Williams AFB
until it was replaced by the RAB in February, 1994. The purpose of the RAB (and the TRC
before it) is to serve as an advisory committee to the USAF on the IRP at Williams AFB. The
RAB, whose expanded membership includes representatives of the USAF, State of Arizona and
federal regulatory agencies, and community stakeholders, meets quarterly to discuss the results of
the field investigations and to discuss proposals for interim or final cleanup actions. In addition
to IRP issues, the RAB covers Base reuse topics.
Ten fact sheets have been written and distributed that describe planned, ongoing, and completed
activities under the IRP at Williams AFB. Six were information updates on progress of environ-
mental investigation. Four others described the proposed plans for cleanup of OU-1, OU-2, OU-
3, and OU-5.
A 35-millimeter slide presentation describing the IRP was developed for the Base Commander's
use with community and civic groups. Before the training wing was de-activated, the
Commander or his designee briefed numerous groups about environmental activities at Williams
AFB.
News releases and public notices have been submitted to the local papers announcing milestones
in the IRP. Topics include:
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• Signing of the FFA
• Availability for comment on engineering evaluation/cost analyses for the Radioac-
tive Instrumentation Burial Area, the Fire Protection Training Area No. 1, and the
Pesticide Burial Area
• Availability of the OU-1, OU-2, OU-3, and OU-5 RI reports for review
• Availability of the OU-1, OU-2, OU-3, and OU-5 proposed plans for public
comment
• Announcement of public meeting to present the proposed plans for OU-1, OU-2,
OU-3, and OU-5.
Fact sheets describing the proposed plans to clean up OU-1 and OU-2 were mailed to the mailing
list contained in the community relations plan, along with the announcement of the public
comment period and the public meeting. The broadcast media also received a public service
announcement giving the time and location of the public meeting. Notices in the Arizona
Republic/Phoenix Gazette announced the public comment periods for OU-1 and OU-2. The
Tribune carried notices for the public comment period for the OU-3 and OU-5 proposed plans.
Four public meetings have been held at the Mesa Conference Center Complex as part of the
community relations program at Williams AFB. Fifty to 75 citizens attended the first meeting
held on June 16, 1992 to present the proposed plan for cleanup of OU-2, and less than 20 citizens
attended the second and third public meetings held October 14, 1993 and February 10, 1994 to
present the proposed plan for cleanup of OU-1. Less than a half dozen bona fide community
members attended the public meeting held on July 18, 1995 to present the proposed plan for
OU-3. RAB members and two persons, one representing the State of Arizona and one
representing the Gila River Indian Community, attended the OU-5 public meeting.
At each public meeting, attendees were given an agenda, a fact sheet, and graphic representations
of cleanup alternatives as handouts. Copies of the FSs and proposed plans were available at each
public meeting for review. Press packets, including the handouts, hard copies of slides, and the
news releases, were available for media representatives who attended the first four meetings.
The presentation materials were provided all attendees of the OU-5 meeting.
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8.0 References
AeroVironment, Inc. (AV), 1986, Installation Restoration Program, Phase II Confirma-
tion/Quantification, Stage 1 Report, Williams AFB, AeroVironment Report AF-FR-84/593,
January 1986.
AeroVironment, Inc. (AV), 1987, Installation Restoration Program, Phase II Confirma-
tion/Quantification, Stage 2 Report, Williams AFB, AeroVironment Report AV-FR-87/536.
Alloway, B. J., 1990, Heavy Metals in Soils, John Wiley & Sons, New Jersey, 339 pp.
Cost Branch Controller Division, 1987, Community Economic Impact Statement, 82nd Flying
Training Wing.
Engineering-Science, Inc. (ES), 1984, Installation Restoration Program, Phase I - Records
Search, Williams AFB, Arizona, February 1984.
Gschwend, P. M. and R. A. Hites, 1981, "Fluxes of Polycyclic Aromatic Hydrocarbons to Marine
and Lacustrine Sediments in the Northeastern United States," Geochim. Cosmochim. Acta,
45:2359-67.
IT Corporation (IT), 1996, Final Remedial Investigation Report, Operable Unit 5 (OU-5),
Williams Air Force Base, prepared for Air Force Center for Environmental Excellence,
HSC/PKCVCB Headquarters Human Systems Center (AFMC), Brooks Air Force Base, Texas,
May 1996.
IT Corporation (FT), 1995a, Final Action Memorandum, Operable Unit 5 (OU-5), Williams Air
Force Base, Arizona, prepared for AFBCA, Williams Air Force Base, June 1995.
IT Corporation (FT), 1995b, Final Field Sampling Plan, Operable Unit 5 (OU-5), Williams Air
Force Base, Arizona, prepared for Air Force Center for Environmental Excellence, HSC/PK-
CVCB Headquarters Human Systems Center (AFMC), Brooks Air Force Base, Texas, June
1995.
IT Corporation (FT), 1995c, Final Report, Installation of Permeable Cap, Landfill LF-04,
Williams Air Force Base, Arizona, prepared for Air Force Center for Environmental Excellence,
HSC/PKCVCB Headquarters Human Systems Center (AFMC), Brooks Air Force Base, Texas,
October 1995.
FT Corporation (IT), 1994a, Final Remedial Investigation Report, Operable Unit 3, Williams
Air Force Base, Arizona, prepared for Air Force Base Conversion Agency, Williams Air Force
Base, Arizona, by IT Corporation, September 1994.
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IT Corporation (IT), 1994b, Final Remedial Investigation Report Addendum, Operable Unit 1,
Williams Air Force Base, Arizona, prepared for Air Force Base Conversion Agency, Williams
Air Force Base, Arizona, January 1994.
IT Corporation (FT), 1994c, Final Evaluation/Assessment Report, Williams Air Force Base,
Arizona, prepared for Air Force Base Conversion Agency, September 1994.
IT Corporation (FT), 1994d, Final Remedial Investigation Report Addendum, Operable Unit I,
Williams Air Force Base, Arizona, prepared for Air Force Base Conversion Agency, Williams
Air Force Base, Arizona, January 1994.
IT Corporation (IT), 1993a, Final Facilities Assessment Report, Williams Air Force Base,
Arizona, prepared for USAF Air Training Command, Randolph Air Force Base, Texas, March
1993.
FT Corporation (IT), 1993b, Final Field Sampling Plan Addendum, Operable Unit 3, Williams
AFB, Arizona, prepared for the USAF Air Training Command, Randolph Air Force Base, Texas,
August 1993.
IT Corporation (IT), 1993c, Final Work Plan Addendum, Operable Unit I, Williams AFB,
Arizona, prepared for the USAF Air Training Command, Randolph Air Force Base, Texas,
August 1993.
IT Corporation (IT), 1992a, Final Remedial Investigation Report, Operable Unit I, Williams
AFB, Arizona, prepared for the USAF Air Training Command, Randolph Air Force Base, Texas,
October 1992.
IT Corporation (IT), 1992b, Final Remedial Investigation Report, Liquid Fuels Storage Area -
Operable Unit 2, Williams Air Force Base, Arizona, prepared for the USAF Air Training
Command, Randolph Air Force Base, Texas, January 1992.
IT Corporation (IT), 1992c, Final Feasibility Study Report, Operable Unit 2, Williams AFB,
Arizona, prepared for the USAF Air Training Command, Randolph Air Force Base, Texas, April
1992.
IT Corporation (IT), 1992d, Final Record of Decision Report, Operable Unit 2, Williams AFB,
Arizona, prepared for the USAF Air Training Command, Randolph Air Force Base, Texas,
December 1992.
IT Corporation (IT), 199la, Williams Air Force Base Final Work Plan and Quality Assurance
Project Plan, prepared for the USAF Air Training Command, Randolph Air Force Base, Texas,
February 1991.
IT Corporation (IT), 1991b, Williams Air Force Base Final Field Sampling Plan, prepared for
the USAF Air Training Command, Randolph Air Force Base, Texas, April 1991.
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IT Corporation (IT), 1991c, Williams Air Force Base Final Community Relations Plan,
prepared for the USAF Air Training Command, Randolph AFB, Texas, by IT Corporation.
FT Corporation (IT), 1987a, Task Report No. 4, Remedial Action Report for the Southwest
Drainage System, Williams AFB, Arizona, prepared for the USAF Air Training Command,
Randolph Air Force Base, Texas, June 10, 1987.
IT Corporation (IT), 1987b, Plans and Specifications for Remediation of the Southwest
Drainage System Ditch, Williams AFB, Arizona, prepared for the USAF Air Training
Command, Randolph Air Force Base, Texas, September 18, 1987.
Kawamura, K. and I. R. Kaplan, 1983, "Organic Compounds in the Rainwater of Los Angeles,"
Environ. Sci. Technol., 17:497-501.
LaFlamme, R. E. and R. A. Hites, 1978, "The Global Distribution of Polycyclic Aromatic
Hydrocarbons in Recent Sediments," Geochimica et Cosmochimica Acta, 42:289-303.
Laney, R. L. and M. E. Hahn, 1986, "Hydrogeology of the Eastern Part of the Salt River Valley
Area, Maricopa and Pinard Counties, Arizona," U.S. Geological Survey, Water Resources
Investigations Report, pp. 86-4147.
National Oceanic and Atmospheric Administration, 1977, Climatic Atlas of the United States,
National Climatic Center, Asheville, North Carolina.
Shuman, L. M., 1991, "Chemical Forms of Micronutrients in Soils," J. J. Montvedt (ed.).
Micronutrients in Agriculture, Soil Sci. Soc. Amer. Book Series No. 4, Soil Sci. Soc. Amer.,
Inc., Madison, Wisconsin.
Sunregion Associates, 1987, Maricopa Land Use Plan, Ocean Creek and East Mesa, Subarea
A2.
Thomas, W., 1986, Accumulation of Airborne Trace Pollutants by Arctic Plants and Soil, Water
Sci. Technol, 18:47-57.
U.S. Department of Housing and Urban Development, 1979, Firm Flood Insurance Rate Map,
Maricopa County, Arizona, Unincorporated Areas: Community, Panel No. 0400371600A.
U.S. Environmental Protection Agency (EPA), 1995, Region IX Preliminary Remediation
Goals (PRGs) First Half 199S, EPA Region DC, San Francisco, California, February 1, 1995.
U.S. Environmental Protection Agency (EPA), 1992, "Guidance on Risk Characterization for
Risk Managers and Risk Assessors," Memorandum from F. Henry Habicht 0, Deputy
Administrator, to Assistant Administrators, Regional Administrators, February 26.
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U.S. Environmental Protection Agency (EPA), 1990, National Oil and Hazardous Substances
Pollution Contingency Plan, Final Rule, FR Vol. 55, No. 46, March 8, 1990, available from
U.S. Government Printing Office, Washington, DC.
U.S. Environmental Protection Agency (EPA), 1989, Risk Assessment Guidance for Superfund,
Human Health Evaluation Manual, Part A, Interim Final, EPA/540/1-89/002, EPA, Office of
Emergency and Remedial Response, Washington, DC.
U.S. Environmental Protection Agency (EPA), 1988a, Laboratory Data Validation: Functional
Guidelines for Evaluating Inorganics Analysis, Office of Emergency and Remedial Response,
Washington, DC.
U.S. Environmental Protection Agency (EPA), 19885, Laboratory Data Validation: Functional
Guidelines for Evaluating Organics Analysis, Office of Emergency and Remedial Response,
Washington, DC.
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