EPA Superfund
Record of Decision:
PB96-964510
EPA/ROD/R09-96/153
December 1996
Williams Air Force Base,
Operable Unit 3, Chandler, AZ
6/8/1996
-------
-------
INSTALLATION RESTORATION PROGRAM
WILLIAMS AIR FORCE BASE, ARIZONA
FINAL
RECORD OF DECISION
OPERABLE UNIT 3 (OU-3)
CONTRACT NUMBER F41624-94-D-8047, ORDER D0007
RECORDS CTR
0465-00134
KW3187/WP3187.COV/01-22-96(9:15am)/DO/El
Project No. 409877
January 1996
-------
-------
Williams Air Force Base, Arizona
Final
Record of Decision
Operable Unit 3 (OU-3)
January 1996
Prepared for:
Air Force Center for Environmental Excellence
HSC/PKVCB
Headquarters Human Systems Center
Brooks Air Force Base, Texas 78235-5353
Delivery Order 0007
Prepared by:
IT Corporation
312 Directors Drive
Knoxville, Tennessee 37923
Project 409877
KN/3187/WP3187.COV/01-22-96(9:15am)/DO/El
-------
-------
REPORT DOCUMENTATION PAGE
FormApproved
QMB No. 0704-01BB
Public reporting burden tor this collection ot information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources.
gathering and maintaining the data needed, and completing and reviewing the collection o( information. Send comments regarding this burden estimate or any other aspect of this
collection of information, including suggestions tor reducing this burden, to Washington Headquarters Services, Drectcrate for information Operations and Reports, 1215 Jefferson
Davis Highway. Suite 1204. Arlington, VA 22202-1302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.
1. AGENCY USE ONLY (Leave blank)
2. REPORT DATE
January 1996
3. REPORT TYPE AND DATES COVERED
Final
4. TITLE AND SUBTITLE
Record of Decision, Operable Un'rt3 (OU-3), WilliamsAir Force Base, Arizona
6. AUTHOR
-------
-------
Table of Contents.
Page
List of Tables v
List of Figures vi
List of Acronyms vii
1.0 Declaration 1-1
1.1 Site Name and Location 1-1
1.2 Statement and Basis of Purpose 1-1
1.3 Assessment of the Site 1-1
1.4 Description of the Selected Remedy 1-1
1.4.1 Fire Protection Training Area No. 2 1-2
1.4.2 Southwest Drainage System 1-3
1.5 Statutory Determinations - Fire Protection Training Area No. 2 1-3
1.6 Declaration Statement - Southwest Drainage System 1-3
2.0 Decision Summary 2-1
2.1 Site Name, Location, and Description 2-1
2.2 Site History and Enforcement Activities 2-4
2.2.1 Fire Protection Training Area No. 2 2-7
2.2.1.1 Site Description and History 2-7
2.2.1.2 Investigations 2-8
2.2.1.3 Other Actions 2-9
2.2.2 Southwest Drainage System 2-9
2.2.2.1 Site Description and History 2-9
2.2.2.2 Other Actions 2-11
2.3 Highlights of Community Participation 2-14
3.0 Scope and Role of Operable Unit 3-1
4.0 Summary of Site Characteristics 4-1
4.1 Fire Protection Training Area No. 2 4-1
4.2 Southwest Drainage System 4-3
4.3 Contaminant Fate and Transport 4-4
4.3.1 Contaminant Persistence in the Environment 4-4
4.3.2 Site-Specific Applications 4-5
4.3.2.1 Fire Training Area No. 2 4-5
KN/31S7/WP3187.CON/01-22-96(10Kl2«nyD(VEl 1
-------
Table of Contents (Continued).
Page
4.3.2.2 Southwest Drainage System 4-6
4.3.2.3 Discussion 4-6
5.0 Summary of Potential Site Risks 5-1
5.1 Introduction 5-1
5.2 Identification of Chemicals of Potential Concern 5-1
5.2.1 Chemicals of Potential Concern for Groundwater 5-2
5.2.1.1 Fire Protection Training Area No. 2 5-2
5.2.1.2 Southwest Drainage System 5-2
5.2.2 Chemicals of Potential Concern for Soils 5-3
5.2.2.1 Fire Protection Training Area No. 2 5-3
5.2.2.2 Southwest Drainage System 5-3
5.2.3 Uncertainties 5-4
5.3 Exposure Assessment 5-4
5.3.1 Receptor Assessment 5-4
5.3.2 Identification of Potential Exposure Pathways 5-5
5.3.2.1 Fire Protection Training Area No. 2 5-5
5.3.2.2 Southwest Drainage System 5-5
5.3.2.3 Ingestion of Homegrown Fruits and Vegetables 5-6
5.3.3 Estimation of Exposure 5-6
5.3.3.1 Exposure Models 5-6
5.3.3.2 Exposure Parameters 5-7
5.3.3.3 Exposure-Point Concentrations . . 5-7
5.3.4 Uncertainties 5-9
5.4 Toxicity Assessment 5-9
5.4.1 Contaminant Toxicity 5-9
5.4.2 Dermal Toxicity Values 5-10
5.5 Risk Characterization 5-10
5.5.1 Carcinogens 5-11
5.5.2 Noncarcinogens 5-11
5.5.3 Chemicals With No Published Toxicity Values 5-12
5.5.4 Results of Risk Characterization 5-13
5.5.5 Vegetable Ingestion Pathway 5-15
5.5.6 Uncertainties 5-15
KN/3187yWP3187.CON/01-22-96(10K)2»myD(l/El ii
-------
Table of Contents (Continued).
Page
5.6 Ecological Assessment 5-17
5.7 Remedial Action Decision Summary for OU-3 5-17
5.7.1 Fire Protection Training Area No. 2 5-17
5.7.1.1 Soil 5-18
5.7.1.2 Groundwater 5-19
5.7.2 Southwest Drainage System 5-18
5.7.2.1 Soil 5-19
5.7.2.2 Groundwater 5-19
5.8 Summary and Conclusions 5-19
5.8.1 Current and Future Land Use 5-19
5.8.2 Baseline Human Health Assessment 5-20
5.8.3 Ecological Assessment 5-21
5.8.4 Remedial Action Decision Summary 5-21
6.0 Description of Alternatives 6-1
6.1 Alternative FT02-1: No Action 6-2
6.1.1 Source Treatment Component 6-2
6.1.2 Source Containment Component 6-2
6.1.3 Groundwater Component 6-2
6.1.4 General Components 6-2
6.1.5 Compliance with ARARs 6-3
6.2 Alternative FT02-4: Soil Vapor Extraction 6-3
6.2.1 Source Treatment Component 6-3
6.2.2 Source Containment Component 6-4
6.2.3 Groundwater Component 6-4
6.2.4 General Components 6-4
6.2.5 Compliance with ARARs 6-5
6.3 Alternative FT02-5: Bioventing 6-6
6.3.1 Source Treatment Component 6-6
6.3.2 Source Containment Component 6-7
6.3.3. Groundwater Component 6-7
6.3.4 General Components 6-7
6.3.5 Compliance with ARARs 6-8
7.0 Comparative Analysis of Alternatives 7-1
KN/3187AVP3187.CON/01-Z2-96{10K)2am)/DCVEl Ul
-------
Table of Contents (Continued).
Page
7.1 Overall Protection of Human Health and the Environment 7-1
7.2 Compliance with ARARs 7-1
7.3 Long-Term Effectiveness and Permanence 7-1
7.4 Reduction in Toxicity, Mobility, and Volume Through Treatment 7-2
7.5 Short-Term Effectiveness 7-2
7.6 Implementability 7-2
7.7 Cost 7-3
8.0 Selected Remedy 8-1
8.1 Major Components of the Selected Remedy 8-1
8.2 Implementation Concerns 8-2
8.3 Cost 8-3
9.0 Statutory Determinations 9-1
9.1 Protection of Human Health and the Environment 9-1
9.2 Attainment of ARARs 9-2
9.3 Cost Effectiveness 9-2
9.4 Utilization of Permanent Solutions and Alternative Treatment Technologies
of Resource Recovery Technologies to the Maximum Extent Possible ....... 9-2
9.5 Preference for Treatment as a Principal Element 9-3
10.0 Documentation of Significant Changes 10-1
11.0 Responsiveness Summary 11-1
11.1 Overview 11-1
11.2 Background on Community Involvement 11-1
11.3 Summary of Comments Received During the Public Comment Period
and Air Force Responses 11-2
11.4 Community Relations Activities at Williams Air Force Base 11-2
12.0 References , 12-1
Appendix A - Chemicals of Concern, Cleanup Levels, and Remedial Action Objectives
for OU-3 Soil and Groundwater
Appendix B - Cost Tables for Fire Protection Training Area No. 2 (FT-02) Remedial
Alternatives
Appendix C - Location-Specific and Action-Specific Applicable or Relevant and
Appropriate Requirements
KN/3187AVP3187.CONA)l-22-96(10K)2amyDO/El IV
-------
List of Tables.
Table Title Follows Page
2-1 Cities Surrounding Williams Air Force Base 2-1
4-1 Background Inorganic Species Concentrations in Soil and Groundwater 4-1
4-2 Analytical Data Summary, Fire Protection Training Area No. 2, Soils 4-2
4-3 Analytical Data Summary, Fire Protection Training Area No. 2,
Groundwater 4-2
4-4 Analytical Data Summary, Southwest Drainage System (SD-09), Soils 4-3
5-1 Analytical Data Summary, Fire Protection Training Area No. 2 (FT-02),
Groundwater 5-2
5-2 Analytical Data Summary, Fire Protection Training Area No. 2 (FT-02), Soils 5-3
5-3 Analytical Data Summary, Southwest Drainage System (SD-09), Surface Soils 5-3
5-4 Analytical Data Summary, Southwest Drainage System (SD-09), Subsurface Soils 5-3
5-5 Summary of Potential Exposure Pathways, Fire Protection Area No. 2 (FT-02) 5-5
5-6 Summary of Potential Exposure Pathways, Southwest Drainage System (SD-09) 5-5
5-7 Parameters Used to Estimate Exposure 5-7
5-8 Estimated Exposure-Point Concentrations for the Fire Protection Training
Area No. 2 5-7
5-9 Estimated Exposure-Point Concentrations for the Southwest Drainage System 5-7
5-10 Summary of Slope Factors 5-10
5-11 Summary of Reference Doses 5-10
5-12 Summary of Dermal Reference Doses and Dermal Cancer Slope Factors 5-10
5-13 Summary of Risk Characterization Results, Fire Protection Training Area No. 2 5-13
5-14 Summary of Risk Characterization Results, Southwest Drainage System 5-13
6-1 FT-02 Soil Alternatives for Inclusion in the Screening Process 6-1
7-1 Comparison of Cleanup Alternatives, Fire Protection Training Area No. 2
(FT-02), OU-3 7-1
7-2 Summary of Remedial Alternative Cost Estimates, Fire Protection Training
Area No. 2 (FT-02), OU-3 7^3
KN/3187/WP3187.CONA)l-22-96<10:02«myD
-------
List of Figures.
Figure Title Follows Page
1-1 Site Location Map . 1-1
1-2 Base Site Map, Williams Air Force Base 1-1
2-1 Fire Protection Training Area No. 2 (FT-02) Monitoring Well and Borehole
Locations 2-8
2-2 Site Map for the Southwest Drainage System (SD-09) 2-9
2-3 Southwest Drainage System (SD-09) Soil Boring Locations for Boreholes
Installed Prior to 1993 2-10
2-4 Sample Location Map, Southwest Drainage System (SD-09) 2-10
2-5 1993 Sample Location Map, Southwest Drainage System (SD-09) 2-12
4-1 Fire Protection Training Area No. 2 (FT-02) Selected Constituent
Concentration Map 4-2
4-2 Fire Protection Training Area No. 2 (FT-02) Vertical Extent of BTEX
Contamination in Soil; Cross-Section A-A' 4-2
4-3 Fire Protection Training Area No. 2 (FT-02) Vertical Extent of BTEX
Contamination in Soil; Cross-Section B-B' 4-2
4-4 SD-09 Ditch and Storm Line Lead Concentrations, 1993 Confirmatory
Sampling 4-3
5-1 Conceptual Exposure Model for OU-3 5-5
6-1 Initial Screening - Soils at FT-02 6-1
6-2 Secondary Screening - Soils at FT-02 6-1
6-3 Remedial Alternative Evaluation Criteria 6-1
6-4 Soil Vapor Extraction (SVE) System Conceptual Flow Diagram,
Fire Protection Training Area No. 2 (FT-02) Soils 6-3
6-5 Bioventing System Conceptual Flow Diagram, Fire Protection Training
Area No. 2 (FT-02) Soils 6-6
KN/3187/WP3187.CON/01-22-96(10:02anyiXyEl VI
-------
List of Acronyms.
ADEQ
ADWR
AFB
ARAR
ATC
AV
bgs
BTEX
Btu
CERCLA
CFR
COC
COPC
CRDL
DOD
DOE
DP-13
EE/CA
Energy Systems
EPA
ES
FFA
FT-02
ESP
FT-03
GAF
HAZWRAP
HBGL
HEAST
HI
HNUS
HQ
HSP
Arizona Department of Environmental Quality
Arizona Department of Water Resources
Air Force Base
applicable or relevant and appropriate requirements
Air Training Command
AeroVironment, Inc.
below ground surface
benzene, toluene, ethyl benzene, and xylene
British Thermal Units
Comprehensive Environmental Response, Compensation, and Liability Act
Code of Federal Regulations
chemical of concern
chemical of potential concern
contract-required detection limit
U.S. Department of Defense
U.S. Department of Energy
Pesticide Burial Area
engineering evaluation/cost assessment
Martin Marietta Energy Systems, Inc.
U.S. Environmental Protection Agency
Engineering-Science
Federal Facilities Agreement
Fire Protection Training Area No. 2
field sampling plan
Fire Protection Training Area No. 1
gastrointestinal absorption factor
Hazardous Waste Remedial Actions Program
health-based guidance levels
Health Effects Assessment Summary Tables
hazard index
Halliburton NUS Corporation
hazard quotient
health and safety plan
KN/3187/WP3187.CON/01-22-96(10^2«myDO/El
Vll
-------
List of Acronyms (Continued).
ffiUBK
ILCR
IRIS
IRP
IT
JP-4
kg
LF-04
MEK
Q
mg/m
mg/kg
msl
NCP
O&M
OU
OWS
PAH
PRG
psig
QAPP
RAB
RAO
RCRA
RD/RA
RfD
RI/FS
RME
ROD
RW-11
RWCD
SARA
scfm
Integrated Exposure Uptake Biokinetic Model for Lead in Children
incremental lifetime cancer risk
Integrated Risk Information System
Installation Restoration Program
IT Corporation
jet petroleum grade 4
kilogram
Landfill
methyl ethyl ketone
micrograms per deciliter
micrograms per liter
milligrams per cubic meter
milligrams per kilogram
mean sea level
National Contingency Plan
operation and maintenance
Operable Unit
oil/water separator
polyaromatic hydrocarbon
preliminary remediation goals
pounds per square inch gage
quality assurance project plan
Restoration Advisory Board
remedial action objective
Resource Conservation and Recovery Act
remedial design/remedial action
reference doses
remedial investigation/feasibility study
reasonable maximum exposure
Record of Decision
Radioactive Instrumentation Burial Area
Roosevelt Water Control District
Superfund Amendment and Reauthorization Act
standard cubic feet per minute
KN/3187/WP3187.CON/01-22-96(10.-02«nyDO/El
Vlll
-------
List of Acronyms (Continued).
SD-09 Southwest Drainage System
SD-10 Northwest Drainage System
SF slope factors
SS-01 Hazardous Materials Storage Area
ST-12 Liquid Fuels Storage Area
SVE soil vapor extraction
SVOC semivolatile organic compound
TCLP Toxicity Characteristic Leaching Procedure
TPH total petroleum hydrocarbon
TRC Technical Review Committee
TVH total volatile hydrocarbon
USAF United States Air Force
USGS U.S. Geological Survey
UST underground storage tank
VOC volatile organic compounds
KN/3187AVP3187.CON/01-22-96(10K)2amyD(VEl IX
-------
-------
1.0 Declaration
1.1 Site Name and Location
Williams Air Force Base (AFB) is located in Maricopa County, Mesa, Arizona (Figure 1-1).
The Fire Protection Training Area No. 2 (FT-02) and the Southwest Drainage System (SD-
09), shown on Figure 1-2 make up Operable Unit (OU)-3. The deep soils at the Liquid Fuels
Storage Area (ST-12) were originally part of OU-3, but the remedy for ST-12 will be
addressed in an amendment to the OU-2 Record of Decision (ROD).
1.2 Statement and Basis of Purpose
This ROD presents the selected remedial action for the sites that compose OU-3 at Williams
AFB. The ROD was developed in accordance with the Comprehensive 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
operable unit.
The U.S. Environmental Protection Agency (EPA) and the State of Arizona concur with the
selected remedy for OU-3.
1.3 Assessment of the Site
Benzene, chloroform, and 1,4-dichlorobenzene are present in FT-02 soils at concentrations
above cleanup levels. Existing conditions at the site have been determined to pose a total
incremental lifetime cancer risk (ILCR) of 3.4 x 10"5 for future residential exposures and 2.0 x
10"5 for current occupational exposures to contaminated soils. The most significant exposure
pathway is inhalation of fugitive dust. The organic contaminants represent a potential future
threat to groundwater at the site due to their concentration and distribution within the soil.
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in this ROD, may present an imminent and
substantial endangerment to public health and the environment.
1.4 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.
KN/3187/WP3187.1/05-03-96(239pmVDl/El 1-1
-------
ro
O
o
i/i
LJ
o
m
oo
01
o
«
O
6
o
O)
o
Tf
6
-3
O
cr
o.
o
<
o
a:
a.
>-
m
APACHE
JUNCTION
a:
o
SKY HARBOR
INTL. AIRPORT
o
c
to
SCALE
FIGURE 1-1
SITE LOCATION MAP
WILLIAMS AIR FORCE BASE
PHOENIX, ARIZONA
10 MILES
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
OTECTION
5 AREA No.2
X
WtfB-10
N832000
PRIMARY ROAD
SECONDARY ROAD
RUNWAYAAXIWAY/APRON
RAILROAD
FENCE
BASE BOUNDARY
HISTORICAL BOUNDARY
BENCHMARK
ROAD TEXT
PERMANENT BUILDING
SEMI-PERMANENT BUILDING
TEMPORARY BUILDING
BUILDING NUMBER
GRID LINE
GRID COORDINATE
POND
BASE PRODUCTION MONITORING WELL
SCALE:
F
0 600 1200 FEET
FIGURE 1-2
BASE SITE MAP
WILLIAMS AIR FORCE BASE
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
40987715 09/13/95 0:10pm Jiubbard
STARTING DATE: 9/13/95
DRAWN BY: J. HUBBARD
DATE LAST REV.:
DRAWN BY:
INITIATOR: W. ANDERSON
PROJECT MGR.: W. CARTER
DRAWING NO.: 4-09877-D-15
PROJECT NO.: 409877
\.
);.."«':£;;>- <« ..**< \f *&"*$ -s -.-.f.siMM:: ...*, ?&.**/ ->w -» J5 *!* ;:s^\»i:» ?* ; i . \
rf "if| f * rl ESgJfii5-pSti[ii2v"t:-;f 4^s^ir^-^----i. \ \
',;>'-
'x '"si!..! yr u//
/Al,, %x
/y _ j -\:^ jyi_;ff
^ ^xF^-IJT^ -tf*^f*"
V\'i I >-X/
^/ ,/" k j r'i--^
-------
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)
- Underground storage tanks (UST) at four areas (ST-05, ST-06, ST-07, ST-08).
OU-2 addresses soil to a depth of 25 feet and groundwater at the Liquid Fuels
Storage Area (ST-12). Soil from a depth of 25 feet to groundwater will be
added to OU-2 in a ROD 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).
OU-4 addresses investigations of contamination at 11 sites.
OU-5 addresses removal actions at eight sites.
The USAF in conjunction with EPA and the State of Arizona have selected cleanup remedies
for OU-1 and OU-2. The deep soils at ST-12 (unsaturated soils below 25 feet) will be
addressed in a future amendment to the OU-2 ROD. Sites FT-02 and SD-09 are the subject
of this ROD. Investigations or removal actions have not yet been initiated for OU-4 or OU-5
because the sites associated with these OUs were only recently identified as areas of potential
contamination.
The description of the selected remedy for each of the OU-3 sites is presented in the
following sections.
1.4.1 Fire Protection Training Area No. 2
The selected remedy for FT-02 involves in situ treatment of approximately 25,000 cubic yards
of soil contaminated with benzene, chloroform, and 1,4-dichlorobenzene at concentrations
above risk-based cleanup levels. A bioventing treatment system will be constructed to inject
air into the subsurface soils, thereby stimulating the biodegradation of these organic contami-
nants to nontoxic compounds by indigenous soil microorganisms. The bioventing system is
comprised of an aboveground blower system and a series of air injection wells placed in the
KN/3187/WP3187.1/05-03-96(239pm)/Dl/El 1-2
-------
contaminated soils. The bioventing system will remain in operation until the concentrations
of benzene, chloroform, and 1,4-dichlorobenzene are reduced to cleanup levels.
A bioventing treatability system was installed and initial respiration tests were conducted in
August 1995. This gave indications of the destruction rate. A second round of respiration
tests began in January 1996.
7.4.2 Southwest Drainage System
No further action is recommended.
1.5 Statutory Determinations Fire Protection Training Area No. 2
The selected remedy is protective of human health and the environment, complies with
federal and state requirements that are legally applicable or relevant and appropriate to the
remedial action, and is cost effective. This remedy uses permanent solutions and alternative
treatment (or resource recovery) technologies to the maximum extent practicable and satisfies
the statutory preference for remedies that employ treatment that reduces toxicity, mobility, or
volume as a principal element. Because this remedy will reduce the concentration of
chemicals of concern (COC) to cleanup levels that permit unrestricted use of and unlimited
exposure to the site, a 5-year review will not be required unless the remedial action is not
fully complete within 5 years of its initiation.
1.6 Declaration Statement - Southwest Drainage System
Previous remedial actions at SD-09 have lowered the health risks associated with exposure to
contaminated soil at the site to an acceptable level as calculated under a residential exposure
scenario. Therefore, no further remedial action is required for SD-09 soil. Because the
limited residual soil contamination is distributed within the top few feet of soil, there is no
evidence of any future threat to groundwater. Therefore, no remedial action is required for
groundwater at the site. Because the residual soil contamination at SD-09 is within health
protective levels that permit unrestricted use of and unlimited exposure to the site, a 5-year
review will not be required for SD-09.
KN/3187/WP3187.1/05-03-96(2:59pm)/Dl/El 1-3
-------
This Record of Decision for Operable Unit Number Three at Williams Air Force Base,
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.
Alan K. Olsen, Director
U.S. Air Force, Base Conversion Agency
l5ate
Julie/Anderson, Director
/Federal Facilities Cleanup Office
U.S. Environmental Protection Agency, Region
Date
Russell F. Rhoades, Director
Arizona Department of Environmental Quality
Date
Rita Pearson, Director
Arizona Department of Water Resources
/ (J Date
KN/3187AVP3187.1/05-03-96(i59pm)/Dl/El
1-4
-------
-------
2.0 Decision Summary
2.1 Site Name, Location, and Description
Williams AFB was a flight training base located in Maricopa County, Arizona approximately
30 miles southeast of Phoenix and just east of Chandler (Figure 1-1). The Base, commis-
sioned as a flight training school, was constructed on 4,127 acres of government land in 1941.
Runway and airfield operations, industrial areas, housing, and recreational facilities are
located on the Base. Training activities started after construction, with jet aircraft training
beginning in 1949. The Base was closed September 30, 1993.
This ROD addresses remedial actions for OU-3, which is comprised of FT-02 and SD-09.
Williams AFB is relatively isolated from any large metropolitan area. It 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. 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.
During its active status, 3,029 military personnel and 869 civilian employees were stationed at
the Base. Many of the military personnel lived off Base in one of the surrounding areas.
The total population actually living on Base, including dependents, was approximately 2,700.
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).
A development plan for the region (Sunregion Associates, 1987), if implemented, will
dramatically 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 in the approximate location of the Town of Queen Creek. The plan is to
KN/3187/WP3187.2/01-22-96(2.-09pm)/D(VEl 2-1
-------
Table 2-1
Cities Surrounding Williams Air Force Base
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
18,100
90,533
29,188
288,091
2,667
141,865
893,983
aApril 1, 1990 Census, Public Law Tape 94-171.
KN/3187/WP3187.2-l/01-22-96(9:20aiODO/El
-------
develop the proposed area residentially and commercially for a 25-year period. If implement-
ed, this development will dramatically impact the demographics and population around the
Base. The closure of Williams AFB could also impact the region.
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.
Department of Housing and Urban Development, 1979). Storm drainage on the Base is
directed to a combination of open channels used to drain most of the Base and underground
drainage structures. 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.
There are at least 90 domestic permitted wells within a 3-mile radius of the Base. These
wells are not affected by the contamination at OU-3. The Base currently performs periodic
monitoring and sampling of groundwater wells on the Base in the vicinity of LF-04 and
ST-12.
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 approxi-
mately 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).
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
topography 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 Mountains, and to the west by South Mountain.
KN/3I87/WP31S7.2/01-22-96(2:09pmyDO/El 2-2
-------
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
crystalline 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 moun-
tains 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 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.
Geologic conditions beneath OU-3 have been characterized by fixed-interval soil sampling
and/or using a combination of continuous coring and geophysics. The deposits encountered
during drilling at OU-3 are correlative to the upper unit of Laney and Hahn (1986) and
possibly to the extreme upper section of their middle unit.
There are two major soil associations 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.
An extensive unsaturated (vadose) zone has been produced in the vicinity of Williams AFB
over the last 50 years by a declining water table caused by irrigation and water supply
withdrawals. However, due to decreased agricultural activity from urbanization and an
KN/3187/WP3187.2/01-22-96(2:09pm)/DO/El 2-3
-------
increased water supply derived from surface sources, groundwater extraction has been
reduced. Groundwater elevations at Williams AFB have been increasing over the last 3 to 4
years at a rate ranging from 2 to 4 feet per year.
Low yearly rainfalls and high evapotranspiration rate of the area reduce the potential for
recharge to occur through the vadose zone at the Base. However, several wet years over the
last decade have likely contributed to the rise of groundwater levels.
Groundwater beneath OU-3 sites is currently encountered at depths ranging from 200 to 235
feet below ground surface. IT Corporation (IT) and other contractors have placed monitoring
wells at two of the OU-3 sites (ST-12 and FT-02) to monitor groundwater quality in two
zones of the aquifer. At both sites, the aquifer comprises two zones, referred to as the upper
and lower portions of the aquifer. Groundwater beneath ST-12 is not a part of OU-3 and
therefore, will not be discussed here. Information regarding this can be found in the OU-2
Report (IT, 1992).
Recent groundwater elevation data (from 1993 to February 1995) indicate that groundwater
flows generally to the northeast at FT-02. This is consistent with previous report flow
directions, even though groundwater elevations have been observed to have risen approxi-
mately 10 feet over the last 5 years. Seasonal groundwater fluctuations can range from 5 to 8
feet between summer and winter months. At FT-02, recent hydraulic gradients range from
0.0023 to 0.0060. Because no site-specific aquifer tests have been conducted in these wells,
the hydraulic conductivity data from ST-12 is used to represent hydrogeologic properties
below FT-02. Using the hydraulic conductivity data from ST-12 and assuming an effective
porosity value of 0.30, the groundwater flow velocity is found to range between 0.05 and 0.2
feet per day.
Groundwater at SD-09 has not been investigated and no monitoring wells have been installed
at this site. However, the Landfill (in OU-1) is immediately south of SD-09 and groundwater
beneath the Landfill (LF-04) is presumably representative of groundwater beneath SD-09. At
LF-04, groundwater is currently measured between 180 to 205 feet below ground surface and
flows from west to east across the site.
2.2 Site History and Enforcement Activities
Williams AFB was a flight training base that opened in 1942. It was immediately commis-
sioned as a flight training school, and training activities with jet aircraft began in 1949.
KN/31g7AVP3187.2/01-22-96(2.-09pmyDO/El 2-4
-------
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 U.S. Department of
Defense (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 (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
Fire Protection Training Area No. 1
Fire Protection Training Area No. 2
Northwest Drainage System
Southwest Drainage System
Radioactive Instrumentation Burial Area
Pesticide Burial Area
Hazardous Materials Storage Area
Liquid Fuels Storage Area.
A second investigation (designated as Phase II) was conducted by AeroVironment, Inc. (AV)
from September 1984 to December 1985. This investigation was initiated to confirm the
information in the ES report and to verify the presence and quantify the extent of contamina-
tion. In 1987, AV 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. Some of the analytical data utilized in this
ROD were collected during this Phase n, Stage 2 investigation.
In 1987, as a result of AV investigations, IT, under a contract with Martin Marietta Energy
Systems, Inc. (Energy Systems) through the Hazardous Waste Remedial Actions Program
(HAZWRAP) (IT, 1987a), performed a simple remedial action. This activity involved
KN/3187/WP3187.2/01-22-96(2;09pm)/D(VEl 2-5
-------
designing soil cementing and a concrete cap for approximately 350 feet of the uppermost
portion of SD-02. 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 Energy Systems and its
subcontractor, IT, through the U.S. Department of Energy (DOE) to complete the remedial
investigation/feasibility study (RI/FS), proposed plan, and ROD at Williams AFB. As part of
these efforts, a work plan and quality assurance project plan (QAPP) (IT, 1991a), which
includes a health and safety plan (HSP), and a field sampling plan (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. The complete list of all Williams AFB
sites then consisted of the following:
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)
USTs at four areas (ST-05, ST-06, ST-07, ST-08).
Williams AFB was added to the 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
cooperative 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 Department of Environmental Quality (ADEQ), and the Arizona Department of
Water Resources (ADWR).
KN/3187/WP3187.2/01-22-%(ZO9pmyDO/El 2-6
-------
A ROD for OU-2 was signed in December 1992. The selected remedy for site ST-12
involves a combination of soil vapor extraction with bioenhancement to remediate affected
soils to a depth of 25 feet, and groundwater extraction and treatment via air stripping with
emission abatement to address the contaminated groundwater. The selected remedy will be
implemented until the COCs (that present an unacceptable risk to human health or the
environment in soil (benzene, 1,4-dichlorobenzene) and groundwater (benzene, naphthalene,
toluene) are reduced to concentrations below cleanup levels.
A ROD for OU-1 was signed in June 1994. The selected remedy for OU-1 involved
installing a permeable cap over the landfill to limit human exposure to dieldrin and beryllium
contaminated surface soils and control natural erosion processes. The remedy also included
measures to restrict access to the site such as warning signs and perimeter fencing, as well as
land-use restrictions to protect the integrity of the landfill cover and the operation of the
groundwater monitoring system.
History of past waste practices, environmental investigations, enforcement activities, and
remedial actions for each OU-3 site is presented in the following sections.
2.2.1 Fire Protection Training Area No. 2
2.2.1.1 Site Description and History
FT-02 is located on approximately 8.5 acres near the southern boundary of the Base (Figure
1-2). FT-02 was used for fire protection training exercises between 1958 and 1991. Waste
solvents, hydraulic fluids, oils, and fuel were burned at the area from 1958 until approxi-
mately 1968. Since 1968, jet petroleum grade 4 (JIM) has been used for training exercises.
Until the mid-1970s, two to three fires were ignited per week. In more recent years, 8 to 12
fire training exercises per quarter have been typical (ES, 1984).
During the 1950s and 1960s, up to 1,000 gallons of flammable material was used per training
exercise. The volume of combustible material decreased to approximately 600 gallons per
event in the 1970s, and then to 300 gallons per exercise from the 1980s until 1991, when
facility use stopped. Extinguishing agents, used until the early 1970s, include protein foam
and chlorobromomethane. In more recent years, aqueous film-forming foam, halon, and dry
chemicals have been used (ES, 1984).
KN/3187/WP3187.2/01-22-96(2:09pmVDO/El 2-7
-------
The area initially used for training consisted of shallow pits on the ground where the
flammable material was placed for burning. Water was applied to the soil before each burn
to minimize the total impact of the waste application by hydrophobic repulsion. However,
not all flammable materials were burned during the fire training exercises. The remaining
material either volatilized or soaked into the ground (ES, 1984).
In 1983, the area was expanded from a single pit to two burn pits, a large pit and a small pit.
The pits were reconstructed to include a concrete liner, and the large pit was equipped with a
drain connected to a collection tank (ES, 1984).
Normally, water and the extinguishing agent used during training exercises filled the liner.
Material that flowed over the liner or that was blown over by wind either volatilized or
percolated into the ground.
2.2.1.2 Investigations
The Phase I document identified FT-02 as an area at Williams AFB where past activities may
have resulted in contamination (ES, 1984). During the Phase n, Stage 1 investigation (AV,
1986), 15 shallow soil borings were installed to a maximum depth of 25 feet (Figure 2-1).
An additional 22 borings were drilled to a maximum depth of 210 feet during Stage 2 work
(AV, 1987). Including geotechnical samples, AV collected 114 soil samples for analyses; of
these, 110 were analyzed for contaminant constituents.
AV installed and collected water samples from five groundwater monitoring wells at FT-02
during the Stage 2 activities (Figure 2-1).
As part of the ongoing RI, IT continued to sample the monitoring wells at FT-02 installed by
AV. Well FT-WS-06 was installed in 1989 to a depth of 225 feet to determine if two
aquifers were present at FT-02. This well was subsequently abandoned in 1991 because it
was dry. Also, IT collected soil samples from a boring that was installed at a 45-degree
angle underneath the large burn pit. The angle boring measured 110 feet along its length and
the bottom of the borehole was approximately 78 feet deep (vertical). This boring was started
at the edge of the large burn pit and drilled so that samples could be collected from below the
concrete liner to determine if contamination existed prior to liner installation. Figure 2-1
presents the locations of borings and wells installed at FT-02.
KN/3187/WP3187.2/01-22-96(Z-09pmyDO/El 2-8
-------
N835.500
f 2-02 (D)
LARGE
BURN PIT
FP-/4
FP-4
SUMP
DRAIN
LINES
I 1 1050
N835.000
1117
o o
1118
INOPERATIVE
LANDING MAT
-------
NOTES:
1. STAGE 1 BOREHOLES 1, 2 & 10
NOT SHOWN.
2.LOCATIONS OF FORMER FEED AND
DRAIN LINES AND SUMP ARE
APPROXIMATE.
F2-04 (D)
0
SMALL
BURN PIT
F2-02NE
F2-02M
F2-02SE
F2-I8
F2-/7
FT-WS-06 (S)
(^(ABANDONED)
FP-9
F2-33
F2-37
F2-36
F2-34
LEGEND:
-^'
FEED LINES
PUMP HOUSE
SCALE:
100
200 FEET
MONITORING WELL
SHALLOW MONITORING WELL
DEEP MONITORING WELL
ANGLED SOIL BORING
STAGE 1 SOIL BORING
STAGE 2 SOIL BORING
T 11050 FACILITY AND NUMBER
A SURFACE SOIL SAMPLE (1394)
FIGURE 2-1
FIRE PROTECTION TRAINING AREA
NO. 2 (FT-02) MONITORING WELL
AND BOREHOLE LOCATIONS
WILLIAMS AIR FORCE BASE
F2-OKD)
Hi
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
A sediment sample was collected in 1991 to further characterize the site. This sample was
collected from the sump that received fluids from both burn pits at FT-02, and was then
analyzed for dioxins and furans. Three surface soil samples were collected from FT-02 in
August 1994 and analyzed for polyaromatic hydrocarbon (PAH).
2.2.1.3 Other Actions
An engineering evaluation/cost assessment (EE/CA) for FT-02 was prepared in 1992 to
evaluate remedial alternatives (IT, 1993a). The first phase of the remedial action recom-
mended by this EE/CA was performed by Halliburton NUS Corporation (HNUS) from
February through April 1994. Phase I consisted of removal of the two fire pits, associated
structures, piping at FT-02, and incidental soil. The following activities were performed as
part of the removal action:
Removal and disposal of more than 5,000 gallons of fluid from the two fire pits
and associated piping
Excavation, removal, and disposal of two concrete fire pits and gravel fill
material; one concrete sump; one steel fuel/water separator; pump house and
slab; and associated steel, concrete, and asbestos piping
Removal and transport of two steel aboveground storage tanks formerly contain-
ing JP-4 and water for off-site destruction and disposal
Backfilling of excavations with clean fill material and restoration of surfaces to
their original condition.
Additional details concerning the removal of the FT-02 structures may be found in the site
activity report (HNUS, 1994). Current plans call for the initiation of bioventing treatability
studies at FT-02 in the latter part of 1995.
2.2.2 Southwest Drainage System
2.2.2.1 Site Description and History
SD-09 consists of the old and the existing southwest drainage ditch. This system has been
present since the Base was constructed in 1941 (AV, 1986). The old portion of SD-09, now
filled in, originated east of 5th Street and ran west-northwest through an area that was the
location of Base housing (Figure 2-2). Aerial photographs show that sometime between 1948
and 1954 the existing portion of this drainage ditch was constructed (IT, 1990).
KN/3187AVP3187^/01-22-96(2:09pm)/DO/El 2-9
-------
P° FORMER
'SOUTHWEST
DRAINAGE
DITCH
RETENTION
IMPOUNDMENT/^ §
-------
JlgBB67 a Jl
UULJUU1 J
RL
STORM LINE OUTFALL
(HEADWORKS OF
SD-03 DITCH)
SOUTHWEST
DRAINAGE
SYSTEM (SD-0S)
-MIDVALE SITE BOUNDARY
(NOTE 2)
STORM LINE
LEGEND:
STORM LINE AND SOIL-CEMENTED
PORTION OF SD-09
(APPROX.350 FT LONG),
REMOVED DECEMBER 1S93
SD-0S DITCH AND FLOW DIRECTION
NOTES:
1. AREA OF STORM LINE COLLAPSE
(REPAIRED 19S2).
2. STORM LINE CONTINUES NORTHWES"
ALONG SOUTH APRON, THEN WEST
ALONG MIDDLE APRON.
/>.
SCALE
iiff
0 200 400 FEET"
FIGURE 2-2
SITE MAP FOR THE SOUTHWEST
DRAINAGE SYSTEM (SD-0S)
WILLIAMS AIR FORCE BASE
I INTERNATIONAL
TECHNOLOGY
I CORPORATION
-------
SD-09 runs for approximately 4,000 feet along the southern edge of the Base housing. The
drainage ditch is a shallow V-shaped channel. The top width spans approximately 15 to 20
feet and the depth ranges from approximately 1 to 5 feet. Approximately 85 percent of this
open channel lies within 100 feet of Base housing.
Because the storm sewer system was connected to SD-09, the system has received rinse water
from the plating shop, aircraft washing wastes, and spills from miscellaneous aircraft and
vehicle maintenance operations. These materials include, but are not limited to fuel,
hydraulic fluid, solvents, oils, paints, and thinners. Drainage from the Hazardous Materials
Storage Area (SS-01) near Building 1080 may have released hazardous substances to SD-09,
and these substances could have traveled through a perforated drainage pipe that led south-
west from SS-01, then northwest, connecting to SD-09.
Investigations. The Phase I document identified SD-09 as an area at Williams AFB where
past hazardous material handling and disposal practices may have resulted in contamination
(ES, 1984). During the Phase n, Stage 1 investigation, AV installed six shallow soil borings
(SW-01 through SW-06) to a maximum depth of 40 feet (Figure 2-3) and collected and
analyzed 12 soil samples (AV, 1986).
In 1987, IT installed 32 shallow boreholes approximately 2 to 3 feet deep from which 32 soil
samples were collected and analyzed. Also, an additional 28 surface soil samples were
collected and analyzed. In 1989, IT installed 5 shallow boreholes (OT-01-SS-01 through OT-
Ol-SS-05) from which 15 subsurface soil samples and another 5 surface soil samples were
collected. The boring logs for these samples are presented in Appendix A of the OU-3 RI
report (IT, 1994). Among these samples, two were taken along the perforated drainage pipe
that led to SD-09 from SS-01. Two additional soil borings were installed in September 1991
(SWD-B-33 and SWD-B-34) to a depth of approximately 40 feet to more fully characterize
SD-09. Eight samples from these borings were analyzed. This addition brought the total
borings installed by IT during the OU-1 RI to 7 and samples analyzed to 23. Locations for
these borings are shown on Figure 2-3.
A total of 45 locations have been sampled during past investigations (through 1992) of the
SD-09. The locations shown in Figure 2-3 were sampled during several different sampling
events beginning with the Phase IE, Stage 1 soil borings in 1984 (AV, 1986).
KN/3187/WP3187^2/01-22-96(2.-09pmyDO/El 2-10
-------
SEWAGE TREATMENT
PLANT
-------
REET
SW-02
-------
Seven surface soil samples (H2353 through H2359) were collected (Figure 2-4) to fill data
gaps at various points along SD-09, including the retention impoundment in accordance with
the approved work plan and FSP addendums for OU-3 (IT, 1993b,c).
2.2.2.2 Other Actions
During Phase II, Stage 1, AV recommended that the soils from a 50-foot length of the
channel be excavated to a depth of 2 feet and removed (AV, 1986). A simple removal action
was performed on SD-09 to remediate a portion of the existing ditch. This removal action
was completed in 1988 and resulted in the upper 350 feet of the drainage channel being soil
cemented and covered with a 4-inch concrete cap.
In 1992, there was a collapse in the storm line upstream of the SD-09 drainage system
headworks (Figure 2-2). Approximately 65 feet of the line was replaced. Due to the
presence of volatile organic compounds (VOC) in the pipe that collapsed, it was determined
that the storm line beginning at Building 53 needed to be investigated. Based on agreement
of the parties to the FFA, the storm line and four oil/water separators (OWS) and associated
piping were added to SD-09 and this site was included in OU-3.
Work performed as part of the OU-3 RI at SD-09 was conducted from November 1993
through January 1994. Field investigation activities included the excavation, removal, and
disposal of the storm line, four OWSs and associated piping, and the capped portion of SD-09
so that samples could be collected from underlying soil. All excavations were backfilled with
clean material. Surface soil samples, along with samples collected from the bottom of the
excavations, were taken for analyses. In addition, composite soil samples and sludge/pipe
samples were collected for the purpose of waste characterization.
The OWSs and associated piping that led to the storm line were excavated and removed for
disposal. Fourteen soil samples were collected from the sides and the bottoms of the
excavations for confirmation that the source of contamination had been removed. Four
additional soil samples were collected along the OWSs discharge pipe trenches. An addi-
tional 2 feet of soil was excavated at these sampling points prior to collecting a undisturbed
sample for analyses. Additional composite soil samples were collected from the stockpiled
soil (H2407), and a sample was collected of the pipe contents for characterization of the
material for disposal. Some of the associated piping contained a sludge-like material with a
slight hydrocarbon odor. Composite samples of the sludge were also collected for analyses
(H2406 and Building 532 OWS-1 [ATI 312537-1]). Analyses performed for waste profile
KN/3187AVP3187.2A)l-22-96(i-09pmVDO/El 2-11
-------
FORMER SOUTHWEST
DRAINAGE DITCH\».
RETENTION
IMPOUNDMENT
-------
PARKING 5
JUUL
Vinnnnnnj
FORMER LOCATION OF
STORM LINE OUTFALL
(HEADWORKS OF SD-OS DITCH)
350 FT
SOIL-CEMENT CAP
(REMOVED)
SOUTHWEST
DRAINAGE
SYSTEM (SD-0S)
H2353
AND
H2354
ALE SITE BOUNDARY
LIQUID FUELS
STORAGE AREA
(ST-12)
(NOTE 2)
SD-0S
STORM LINE
LEGEND:
>353
H SURFACE SOIL SAMPLE (6-12 IN. BELOW
CENTERLINE OF SD-0S DITCH) AND
SAMPLE ID NUMBER.
STORM LINE, OWS PIPING AND CEMENTED
PORTION OF SD-0S (REMOVED)
SAMPLED DECEMBER 1SS3
NOTES:
1. SEE FIGURE 1-13 FOR LOCATION OF
SAMPLES COLLECTED UNDERNEATH
REMOVED SOIL-CEMENTED CAP,
STORM LINES. AND OWS PIPING
2. STORM LINE CONTINUES NORTHWEST
ALONG SOUTH APRON, THEN WEST
ALONG MIDDLE APRON.
SCALE
200 400 FEET
FIGURE 2-4
SAMPLE LOCATION MAP
SOUTHWEST DRAINAGE SYSTEM
(SD-0S)
WILLIAMS AIR FORCE BASE
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
consisted of analyses for ignitability, paint filter test (Method 9095), petroleum hydrocarbons
(Method 418.1), reactivity, Resource Conservation and Recovery Act (RCRA) metals by
Toxicity Characteristic Leaching Procedure (TCLP) (Method 1311), chlorinated hydrocarbons
(Method 8010), and aromatic hydrocarbons (Method 8020) analyses. Rpe containing any
sludge-like material was placed in a roll-off bin, crashed, and disposed of as a hazardous
waste at the licensed landfill owned by Laidlaw Environmental Services in Buttonwillow,
California. The soil and incidental concrete and pipe were disposed of at the Butterfield
Station Facility in Mobile, Arizona.
During excavation of the storm line, the soil was stockpiled on plastic along the sides of the
excavation in accordance with the approved work plan addendum. Initially, the soil was
excavated to the top of the pipeline so that the clean soil could be separated from the possibly
contaminated soil. Then, the pipeline was removed and an additional 2 feet of soil were
excavated and stockpiled. The soil was examined for evidence of contamination and field
screening measurements with an HNu. In addition, 22 soil samples were collected from the
bottom of the excavation (at an approximate 5.5- to 6.5-foot depth) at approximately 50-foot
intervals (Figure 2-5). Later, composite samples (H2408, H2409, and H2410) were collected
from the stockpiled soil for waste characterization. Samples were collected in accordance
with the approved work plan and FSP addendums for OU-3 (IT, 1993b,c). Results from the
stockpiled soil indicated that the excavated soil was contaminated but nonhazardous.
Consequently, the soil was transported to the Butterfield Station Facility in Mobile, Arizona
for disposal as a special waste.
The concrete cap and approximately 1 foot of soil underneath it were excavated, along 350
feet of SD-09 during December 8 through 14, 1993. The concrete cap had been installed as
part of the remedial action that occurred in 1987. Eight surface soil samples (H2396 through
H 2403) were then collected at approximately 50-foot intervals along the excavated 350-foot
section of the drainage ditch and analyzed in accordance with the approved work plan and
FSP addendums for OU-3 (IT, 1993b,c). Sample locations are shown on Figure 2-5. The
excavated material was segregated and stockpiled for characterization for disposal. Com-
posite samples were collected from the stockpiled soil (H2411) and concrete (SD-09 concrete
[ATI 312537-02]) to determine the waste profile for disposal. The excavation was backfilled
using clean material and the excavated material hauled off site for disposal. The excavated
soil and concrete were hauled to the Butterfield Station Facility in Mobile, Arizona for
disposal as a special waste.
KN/3187/WP3187i/01-22-96(Z-09pmyD
-------
innr
JULJl
H2375
H2376
H2380
H2385
H2390
NEW DIVERSION
STORM LINE
H2392
H2382
H2383
H2384
STORM LINE
(REMOVED)
ABANDONED
STORM LINES
FORMER LOCATION OF
STORM LINE OUTFALL
(HEADWORKS OF SD-09 DITCH)
350 FT SOIL-CEMENT CAP
(REMOVED)
ABANDONED
PERFORATED
STORM LINcS
H2353 AND H2354
SEE FIGURE 1-12
FOR CONTINUATION
OF SD-09 DITCH AND
SAMPLING LOCATIONS
-------
CONCRETE VALVING
STRUCTURE
'SURFACE WATER
RETENTION PONID
SCALE:
0
225
450 FEET
LEGEND:
H2365
B
A
SOIL SAMPLE LOCATION &
SAMPLE ID NUMBER.
STORM SEWER MANHOLE (SMH-XX)
OIL/WATER SEPARATOR
REMOVED SEPTEMBER, 1993
EXISTING STORM SEWER (REMAINING
IN SERVICE)
STORM SEWER ABANDONED AFTER
REMOVAL OF SOIL-CEMENTED CAP
AND CONNECTING STORM LINE
IN DECEMBER 1993
CEMENTED PORTION OF SD-09
(REMOVED) SAMPLED (SOIL)
DECEMBER 1993
STORM LINE & OWS PIPING (REMOVED
SAMPLED (SOL) DECEMBER 1993
| STORM SEWER CATCH BASIN
(SCB-XX)
532 BUILDING AND NUMBER
NOTES:
1. SOIL SAMPLES COLLECTED AT APPROX-
IMATELY 50 FOOT INTERVALS ALONG
AND BENEATH STORM LINE, OWS PIPING
AND SD-09 CONCRETE LINED DITCH
.AFTER REMOVAL OF PIPE AND CONCRETE.
2. A TOTAL OF EIGHT SOIL SAMPLES NOT
SHOWN WERE COLLECTED FROM BENEATH
THE OIL/WATER SEPARATORS AFTER
REMOVAL.
3. LOCATIONS OF BUILDINGS, ROADS, UTILITIES
ETC., AND SAMPLE LOCATIONS ARE
APPROXIMATE.
FIGURE 2-5
1993 SAMPLE LOCATION MAP
SOUTHWEST DRAINAGE SYSTEM (SD-09
WILLIAMS AIR FORCE BASE
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
A total of 49 soil samples were collected from SD-09, the storm line, the OWS, and associ-
ated piping excavations between September 29, 1993 and December 10, 1993 to better define
the nature and extent of contamination. In addition, six composite samples were collected
from the stockpiled soil for waste profiling prior to off-site disposal.
Eight soil samples were collected from the OWS excavations at Buildings 53, 532, and 533,
and four soil samples from underneath the removed associated discharge piping. Twenty-two
soil samples were collected from underneath the removed storm drain pipe between the
headworks at the SD-09 ditch and a location approximately 17 feet southwest of the new
manhole associated with the new diversion storm drain, south of Building 53. Eight surface
soil samples were collected from under the 350-foot-long concrete cap at SD-09 after
excavation of the concrete and approximately 1 foot of soil. An additional seven surface soil
samples were collected from the SD-09 ditch and surface impoundment.
Soils from the excavations were stockpiled and composite soil samples were collected to
establish a waste profile prior to off-site disposal. A pipe leading from the OWS at Buildings
53 and 532 to the storm line contained a material resembling sludge. This sludge material
had a hydrocarbon odor; however, no significant concentrations of contaminants were detected
with the HNu. Composite samples of the sludge were also collected for analyses to identify a
waste profile. Composite samples were analyzed by Analytical Technologies, Inc. and
Laidlaw Environmental Services.
A total of eight composite samples, including two sludge samples from the OWS piping and a
concrete sample, were collected by IT and analyzed by Analytical Technologies, Inc. An
additional two composite sludge samples from the OWS piping and a concrete sample were
collected by IT for analyses by Laidlaw Environmental Services for establishing the waste
profile. Analytical results for the waste profile samples are presented in Appendix G of the
OU-3 RI report (IT, 1994).
The excavated soils and concrete were ultimately disposed of off site as a special waste at the
Butterfield Station Facility in Mobile, Arizona. The sludge and associated piping were
disposed of as a hazardous waste at Laidlaw Environmental Services in Buttonwillow,
California.
KN/3187/WP3187.2/01-22-96(2.-09pmyD
-------
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 surrounding community through mailings, public announcements in the local newspaper,
public meetings, public comment periods, public service announcements, and the establish-
ment 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 IX, the ADEQ, ADWR, and the Maricopa County Depart-
ment of Health.
With the advent of Base closure, the TRC was expanded to include additional community
stakeholders 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
part 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-3. The removal action at site FT-02 (one of three
sites in OU-3) was described in an EE/CA released to the public in February, 1993.
Concurrently, these documents were made available to the public in the Administrative
Record. The notice of their availability was published in the Arizona Republic/Phoenix
KN/3187/WP3187^/01-22-96(2.-09pmyD(VEl 2-14
-------
Gazette on February 17, 1993, an action which coincided with the beginning of the 30-day
public comment period.
The USAF has met the community relations requirements of CERCLA Sections 113 and 117
in the remedy selection process for OU-3 through the following activities. The OU-3 RI/FS
was released for public review on June 26, 1995. This release was followed by an
announcement in the Arizona Republic/Phoenix Gazette of the issuance of an OU-3 proposed
plan for public comment and a public meeting. The 30-day public comment period on the
proposed plan began June 26, 1995 and a public meeting was held July 18, 1995 in the City
of Mesa, Arizona to discuss the proposed remedial alternatives. A fact sheet describing the
proposed plan was distributed at the public meeting, placed in the information repositories,
and to other interested individuals upon request. All written and oral comments received
during the public comment period and the corresponding USAF responses are included in the
Responsiveness Summary (Chapter 11.0).
KN/3187/WP3187^/Dl-22-96(i09pmyDO/El 2-15
-------
3.0 Scope and Role of Operable Unit
As with many Superfiind sites, the problems at Williams AFB are complex. As a result, the
USAF has organized the work into five operable units. These are described in Section 1.4.
OU-1 includes the contaminated soils and groundwater at ten sites. Of the ten sites within
OU-1, only the Landfill (LF-04) presents an unacceptable risk to human health and the
environment. Surface soils at LF-04 are contaminated with beryllium and the pesticide
dieldrin at concentrations above cleanup levels. The selected remedy for LF-04 involves the
installation of a permeable cap over the site to limit human exposure to dieldrin and beryllium
contaminated surface soils and control natural erosion processes. The remedy also includes
measures to restrict access to the site, such as warning signs and perimeter fencing, as well as
land-use restrictions to protect the integrity of the LF-04 cover and the operation of the
groundwater monitoring system.
The principal risks to human health and the environment at OU-2 result primarily from
contamination of soil and groundwater by JP-4 and its constituents (e.g., benzene, toluene),
although other organic compounds have also been detected at the site. The ROD for OU-2
was signed in December 1992. The selected remedy involves a combination of soil vapor
extraction with bioenhancement to remediate affected soils to a depth of 25 feet, and
groundwater extraction and treatment via air stripping with emission abatement to address the
contaminated groundwater. The remedial design/remedial action phase for OU-2 was
conducted with a pilot study/demonstration study on the treatment of contaminated ground-
water and a pilot study on the treatment of contaminated soils.
OU-3, addressed by this ROD, includes the contaminated soil at two sites, FT-02 and SD-09.
Of these two sites, only FT-02 requires remedial action to reduce the concentration of
benzene, chloroform, and 1,4-dichlorobenzene to cleanup levels. The principal threat at the
site is the potential migration of soil contaminants to groundwater.
Investigations at OU-4 and removal actions at OU-5 have been completed, and reports are
being prepared to document the work activities performed at these sites.
KN/3187/WP3187.3A)l-22-96(9:20amVDO/El 3-1
-------
-------
4.0 Summary of Site Characteristics
Chapter 4.0 provides an overview of the assessments conducted during the RI to characterize
each site within OU-3. This summary presents the following information:
Quantity, types and concentrations of hazardous substances
Estimated volume of contaminants
Lateral and vertical extent of contamination
Mobility of identified contaminants
Potential surface and subsurface pathways of contaminant migration.
Related information concerning site characteristics include suspected source areas at each site
(Sections 2.2.1 through 2.2.2) and risk evaluations, contaminant carcinogenicity and potential
routes of human and environmental exposures (Chapter 5.0).
Background concentrations have been developed for both soil and groundwater. For each
matrix, regional ranges and Base-specific ranges have been compiled for inorganic species.
Regional background ranges for soil and groundwater were developed from U.S. Geological
Survey (USGS) data. For groundwater, data was obtained from wells within a 10-mile radius
of the Base. For regional soil, USGS data for surficial soils were compiled from Maricopa
and adjacent counties. Table 4-1 provides the regional background ranges for inorganic
species for soil and groundwater.
Base-specific background concentration ranges for inorganics have been developed throughout
the course of the RI. Background soil ranges were obtained from surface soil samples
collected across the extent of the Base. Background groundwater ranges were compiled from
site-specific background monitoring wells at certain sites on Base. Only more recent
sampling data from background wells have been used to determine the Base-specific ranges
for inorganics. Base-specific background ranges are shown in Table 4-1. Additional
information concerning the development of the various background ranges for soil and
groundwater is available in the OU-3 RI report (IT, 1994).
4.1 Fire Protection Training Area No. 2
Soils. The boundaries of the large and small burn pits (site source areas) are defined and the
waste disposal practices are documented in Section 2.2.1. Soil samples were obtained
primarily from within and adjacent to the pits (Figure 2-1).
KN/3187/WP3187.4A)l-22-96(9:21am)/DO/El 4-1
-------
Table 4-1
Background Inorganic Species Concentrations
in Soil and Groundwater
Williams Air Force Base
Constituent
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
Groundwater <^g/L)
Base-Specific
Range3
NDe
ND
NA9
ND
ND
5.2 to 724'
NA
ND
ND
ND
40102160*
ND to 2.1j
ND
ND
ND to 13.3*
Regional
Rangeb
_f
1 to 44
7 to 150
<0.5 to 0.7
<1.0
-
<3to3
<10to30
<10 to 14
-
-
1 to 3
-
-
<3to38
Soil (mg/kg)
Base-Specific
Range0
ND (<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
Ranged
< 1
2 to 97
-
1.0 to 1.5
0.01 to 2.0h
15 to 100
-
15 to 200
10 to 100
0.01 to 0.5h
7 to 50
0.1 to 5h
0.01 to 8h
0.1 to 0.8h
25 to 150
aWells used to establish a Base-specific range: SS01-W-10, SS01-W-17, SS01-W-26, SS01-W-27, LF01-W-12
(September 1993 sampling).
bData obtained from U.S. Geolog'ical Survey WATSTORE Database using wells located within 10 miles of Williams AFB.
cThe average soil concentration represents the mean of nine surface soil samples plus one duplicate collected at
Williams AFB in September 1993. The range presents the tow and high values for the ten samples.
dData obtained from surficial soils in Gila, Maricopa, Pima, Final, and Yuma counties.
e ND = not detected.
'- = not available .
9NA = 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.
h Data obtained from B. J. Alloway, 1990.
'Wells used to establish a Base-specific range: SS01-W-10, SS01-W-17, SS01-W-26, SS01-W-27, LF01-W-12
(September 1993, December 1993, and March/April 1994 sampling). Range represents detected concentrations.
'Analyte concentration is between instrument detection limit (IDL) and contract-required detection limit (CRDL).
KN/3187/WP3187.4-lA>l-22-96(9:21«m)/DO/El
-------
Various VOCs were detected in soils in the area of the small burn pit during the Phase n,
Stage 2 sampling. Detected compounds include chlorinated benzenes at concentrations up to
120 milligrams per kilogram (mg/kg), benzene, toluene, ethyl benzene, and xylene (BTEX),
with a maximum benzene concentration of 310 mg/kg at a depth of 76 feet below ground
surface (bgs), and methyl ethyl ketone (MEK, or 2-butanone) at concentrations of 1,400
mg/kg. Total petroleum hydrocarbons (TPH) concentrations were also detected at a depth of
66 feet with concentrations of 84,000 mg/kg. Deep contamination is present only within the
small burn pit and in areas surrounding it (Figure 4-1). Only slight surface soil contamination
was found in the large burn pit. Low levels of various organic compounds, including
methylene chloride, acetone, and bis(2-ethylhexyl)phthalate, all common laboratory contami-
nants, were detected at the large bum pit.
The presence of relatively high concentrations of TPH at depth in the small burn pit suggests
that either a significant pathway exists for deep migration of chemicals at the small burn pit
or that fire fighting practices differed significantly between the two pits. Cross sections are
shown in Figures 4-2 and 4-3 which show the depths of contaminant detections at both burn
pits. A summary of constituents detected in FT-02 soil samples is presented in Table 4-2.
The estimated volume of impacted soils based on the area! extent and depth of contamination
is approximately 25,000 cubic yards in the small burn pit and 230 cubic yards in the large
burn pit
Inorganic concentrations in soil samples collected from both burn pits were compared to
background concentrations in Table 4-1. Mercury and cadmium were the only analytes that
exceeded their respective regional and Base-specific background ranges. Mercury was
detected in only one sample and appears to be an anomaly. Cadmium exceeded the normal
ranges in four samples with a maximum concentration of 5 mg/kg.
Groundwater. Five groundwater monitoring wells were installed during Phase n, Stage 2
activities. A summary of the detected constituents in groundwater is presented in Table 4-3.
Various VOCs have been reported in several groundwater samples at low concentrations
(maximum concentration of 6 micrograms per liter (|ig/L). TPH have been reported at
concentrations from 1,000 to 6,000 Hg/L but no BTEX components were detected in these
same samples. Recent groundwater samples collected in 1994 did not report any VOCs in the
groundwater.
KN/3187/WP3187.4/01-22-96(921am)/DO/El 4-2
-------
1
I
d
|
o
F2-02
CO
01
o
o
o
F2-1
BOREHOLE F2-17
BENZENE
CHLOROFORM
1 . 4 01 CHLOROBENZENE
DATE
10/86
10/86
10/86
2 FEET
U
U
u
6
FEET 11
20
U
11
FEET
U
U
32
?]
FEET
18
2
32
"I
FEET
U
U
U
UNI TS
MG/KG
MG/KG
MG/KG
BOREHOLF FP-18
BENZENE
CHLOROFORM
1 . 4 DI CHLOROBENZENE
DATE
10/86
10/86
10/86
2 FEET
7
U
5
6 FEET
U
1
U
11 FEET
U
U
U
21 FEE"
U
U
U
4! FEET UNI Tc
U MG/KG
1 MG/KG
U MG/KG
BOREHOLE F2-24
BENZENE
CHLOROFORM
1.4 DICHLOROBENZENE
DATE
10/86
10/86
10/86
2
FEET
U
U
U
6 FEET
U
U
U
11 FEET
U
U
U
21
FEET
U
U
u
41 FEET
U
U
U
UNITS
mg/kg
mg/kg
mg/kg
F2-03 (D)
LARGE
BURN PIT-
FHI
1049
SUMP I I
DRAIN
LINES
BOREHOLE F2-25
BENZENE
CHLOROFORM
1.4 DICHLOROBENZENE
DATE
10/86
10/86
10/86
2 FEET
10
U
12
6 FEET
3
U
2
11 FEET
U
U
u
21 FEET
U
U
U
41 FEET
U
U
U
UNITS
mg/kg
mg/kg
mg/kg
\/
i
BOREHOLE FT02-B-OKD)
BENZENE
CHLOROFORM
1,4 DICHLOROBENZENE
DATE
7/90
7/90
7/90
6 FEET
U
U
U
11 FEET
U
U
u
41 FEET
U
U
U
_ 61 FEET
U
U
U
86 FEET
U
U
U
106 FEET UNITS
U mg/kg
U mg/kg
U mg/kg
8
3
BOREHOLE F2-20
BENZENE
CHLOROFORM
1.4 DICHLOROBENZENE
DATE
10/86
10/86
10/86
2 FEET
U
U
U
6 FEET
U
U
U
11 FEET
U
U
2
. 21 FEET
U
U
U
41 FEET
U
U
2
UNITS
mg/kg
mg/kg
mg/kg
z
BOREHOLE F2-21
BENZENE
CHLOROFORM
1,4 DICHLOROBENZENE
DATE
10/86
10/86
10/86
2 FEET
U
U
U
6 FEET
U
U
3
11 FEET
U
U
U
26 FEET UNITS
U mg/kg
U mg/kg
U mg/kg
,O
o
c
IS
|v
|v
|
X
e\
a.
-------
IDLE F2-16(D)
NE
iOFORM
CHLOROBENZENE
N
\
DATE 7 FEET
10/86 83
10/86 U
10/86 56
\
BOREHOLE F2-23 (D)
BENZENE
CHLOROFORM
1.4 DICHLOROBENZENE
\
16 FEET
54
U
31
\
DATE
10/86 ;
10/86 ;
10/86
26 FEET
24
- U
22
2 FEET
22
u
34
41
13
U
18
6 FEET
5
U
38
FFFT 56 FEET
55
U
23
11 FEET
12
U
26
66 FEET
310
U
120
26 FEET
22
U
22
76 FEET
52
U
23
41 FEET
41
U
34
86 FEET 101 FEET UNITS
U
U
U
56 FEET UNIT"
43 mg/kg
U mg/kg
31 mg/kg
\ 0F2-04 (D) % \
\ . i ji . . i
U mg/kg
U mg/kg
U mg/kg
3.
BOREHOLE F2-?7
BENZENE
CHLOROFORM
1.4 DICHLOROBENZENE
DATE
10/86
10/86
10/86
fi FFFT 11 FFET 41
U
U
u
u
2
U
FFFT 51 FEFT UNITS
U
U
6
U
U
U
mg/kg
mg/kg
mg/kg
F2-36
F2-35 (D)
'F2-34
FEED
LINES-
F2-/2
PUMP HOUSE
ri M
:ET
21 FEET
8
u
23
41 FEET
3
U
3
51 FEET UNITS
6 MG/KG
U MG/KG
2 MG/KG
F2-J/ 1
:T
j
j
13
6 FEET
2
U
16
11 FEET
U
U
U
26 FEET
U
U
11
UNITS
mg/kg
mg/kg
mg/kg
BOREHOLE F2-32 DATE 1.5 FEET
BENZENE
1.4 DICHLOROBENZENE
10/86
10/86
17
12
UNITS
mg/kg
mg/kg
LEGEND:
MONITORING WELL
ANGLED SOIL BORING
STAGE 1 SOIL BORING
STAGE 2 SOIL BORING
NONE DETECTED
SHALLOW MONITORING WELL
DEEP BORING OR
MONITORING WELL
IZ-fe-EI PATH OF ANGLE BORING
NOTES:
1. STAGE 1 SOIL BORINGS FP-01,
FP-02, AND FP-10 (NOT SHOWN)
ARE SOUTH OF F2-26 AND WERE
NOT ANALYZED FOR THE SELECTED
CONSTITUENTS PRESENTED.
2. BORINGS SHOWN WITHOUT DATA
EITHER HAD NO DETECTS OR WERE
NOT ANALYZED FOR THE
CONSTITUENTS PRESENTED.
SCALE
100
200 FEET
FIGURE 4-1
FIRE PROTECTION TRAINING
AREA NO. 2 (FT-02) SELECTED
CONSTITUENT CONCENTRATION MAP
WILLIAMS AIR FORCE BASE
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
i
A'
HVO
(CM
BOTTOM OF SOIL
"
BOnoMOFSOIL
CONTAWIMATION '
APPfWXIMATE DEPTH TO onOUNOWATER
^.EGEND:
H-3t SOIL BORIM3 NtMBER
«OllSAMPLEANM.VTICALReSU.T
FOHBENZOJE/tOTALBTEX(pf>m)
K> COUPOUND(S) NOT DETECTED
FIGURE 4-2
FIRE PROTECTION TRAINING
AREA NO. 2 (FT-02)
VERTICAL EXTENT OF BTEX
CONTAMINATION IN SOIL;
CROSS-SECTION A-A'
WILLIAMS AIR FORCE BASE
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
B*
BOTTOM OF SOU.
CONTAMINATION
APPROXIMATE DEPTH TO QROUNDWATER
LEGEND:
FJ 27 SOIL BORINQ NUMBER
BOIL SAMPU AHALYT1CM. RESULT
FOR BENZENE/TOTAL BTEXtaxn)
HO COMPOUNDS) NOT DETECTED
SCALE:
FIGURE 4-3
FIRE PROTECTION TRAINING
AREA NO. 2 (FT-02)
VERTICAL EXTENT OF BTEX
CONTAMINATION IN SOIL;
CROSS-SECTION B-B1
WILLIAMS AIR FORCE BASE
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
Table 4-2
Analytical Data Summary
Fire Protection Training Area No. 2, Soils
Williams Air Force Base
(Page 1 of 2)
Analyte
Frequency of
Detection
Range of Detection
Limits
(mg/kg)
Range of Detected
Concentrations
(mg/kg)
Arithmetic
Mean8
(mg/kg)
Base-Specific
Range of
Background*3
(mg/kg)
Regional Range of
Background0
(mg/kg)
Organlcs
1,1,1 ,2-Tetrachloroethane
1,1-Dichloroethene
1 ,2-Dichlorobenzene
1 ,3-Dichlorobenzene
1 ,4-Dichlorobenzene
Acetone
Benzene
Bromoform
Bis(2-ethylhexyl)phthalate
Chlorobenzene
Chloroform
Ethyl benzene
Methyl ethyl ketone
Methylene chloride
Toluene
Xylenes
1/64
1/70
24/118
7/182
31/118
6/6
25/115
1/70
5/9
1/179
4/70
39/115
22/70
32/70
28/115
41/115
1.0
0.005 to 1.0
0.34 to 1.0
0.34 to 1.0
0.34 to 1.0
0.011 to 0.01 2
0.005 to 2.0
0.005 to 1.0
0.34 to 0.40
0.005 to 1 .0
0.005 to 1.0
0.005 to 1.0
0.011 to 10.0
0.005 to 2.0
0.005 to 2.0
0.005 to 2.0
1.0
2.0
3.0 to 23.0
3.0 to 47.0
2.0 to 120.0
0.01 to 0.029
2.0 to 31 0.0
1.0
0.078 to 2.3
5.0
1.0 to 2.0
1.0 to 170.0
13.0 to 1400
0.075 to 11.0
3.0 to 260.0
2.0 to 640.0
1.0
2.0
10.5
16.6
22.3
0.017
33.9
1.0
0.97
5.0
1.5
15.9
215.5
5.1
34.8
69.5
NAd
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
KN/3187/WP3187.4-2/01-22-96(9:22am)/DO/El
-------
Table 4-2
Analytical Data Summary
Fire Protection Training Area No. 2, Soils
Williams Air Force Base
(Page 2 of 2)
Analyte
Frequency of
Detection
Range of Detection
Limits
(mg/kg)
Range of Detected
Concentrations
(mg/kg)
Arithmetic
Mean3
(mg/kg)
Base-Specific
Range of
Background13
(mg/kg)
Regional Range of
Background0
(mg/kg)
Inorganics
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Zinc
5/6
6/6
6/6
159/186
1/6
4/6
6/6
1.0 to 2.0
3.0
6.0 to 7.0
0.6 to 10
0.3
9.0 to 20
5.0 to 6.0
1.0 to 5.0
4.0 to 24
13 to 44
4.0 to 70
5.3
13 to 28
33 to 100
3.2
13.8
24.7
17.0
5.3
19.5
62.3
ND(<1)
16.9 to 24.8
ND (<5)
10.4 to 19.4
ND (<0.2)
15.6 to 24.7
ND (<4)
0.01 to 2.0
15 to 100
15to200e
10 to 100
0.01 to 0.5e
7 to 50
25 to 150
a Only detected concentrations were used to compute the arithmetic mean.
b Base-specific range for inorganics from site-specific background soil samples collected at Williams AFB in September 1993. The range represents the highs and lows for the
ten samples collected.
c Data obtained from surficial soils in Gila, Maricopa, Pima, Pinal, and Yuma counties.
d NA = Not available or not used for comparison.
e Data obtained from B.J. Alloway, 1990.
NOTE: Total petroleum hydrocarbons (TPH) and oil and grease are not included in the risk assessment and are not summarized in this table. All data is presented
in Appendix G of the OU-3 FS report.
KN/3187/WP3187.4-2/01 -22-96(9:22am)/DO/El
-------
Lead and zinc have been the only metals reported for any groundwater sample collected at
FT-02. A summary is included in Table 4-3. Concentrations for both metals have exceeded
background ranges. The samples that contained these analytes were collected in or prior to
1989. Groundwater samples collected in 1994 reported an estimated lead concentration of 2.2
|ig/L (below detection limits) in one of four samples (zinc was not analyzed).
4.2 Southwest Drainage System
Soils. A total of 45 locations were sampled at SD-09 prior to 1993 (Figure 2-3), over
several sampling events. Both organic and inorganic constituents were detected in soil
samples collected. However, the organic results mainly reported common laboratory
contaminants, including acetone and phthalates. Phenol and TPH have also been reported at
relatively low concentrations.
Soil samples were collected in 1984, 1989, and 1991 for metals analysis at SD-09. Lead has
been frequently detected in soil samples at concentrations similar to its background ranges,
with limited exceptions. Additional information on this phase of work is discussed in the
OU-1 RI report (IT, 1992). In 1993, a total of 49 soil samples were collected during more
recent site work associated with storm line, OWS, and piping excavations along SD-09.
Sample locations are shown in Figure 2-5. A summary of the results from the 1993 work is
included in Table 4-4.
VOCs were reported in few samples collected in 1993. The highest detected concentration
was 0.011 mg/kg of toluene. SVOCs were also detected. Four phthalates were detected
relatively frequently, but at low concentrations. These compounds are suspected to have been
introduced by the sample handling equipment, or by the laboratory during analysis.
Seven metals were detected in more than 40 percent of the samples collected (Table 4-4).
Reported concentrations are generally within one order of magnitude of the Base-specific
background ranges (Table 4-1). Lead was detected 48 of 49 samples collected in 1993, at a
maximum concentration of 297 mg/kg. However, the 297 mg/kg detection is three times
greater than other surface and subsurface samples collected in this area and areas downstream
of the sample location. Therefore, this detection is considered to be an analytical anomaly.
Only 2 of the 49 samples reported lead concentrations above the Arizona health-based
guidance levels (HBGL) of 84 mg/kg. Figure 4-4 displays the majority of the lead detections
along SD-09 during the 1993 sampling work.
KJs'/3187/WP3187.4A)l-22-%(9:21jm)/DO/El 4-3
-------
Table 4-3
Analytical Data Summary
Fire Protection Training Area No. 2, Groundwater
Williams Air Force Base
Analyte
Frequency of
Detection
Range of Detection
Limits
Range of Detected
Concentrations
Background
Range3
Arithmetic
Meanb
Organlcs (u,g/L)
Acetone
Carbon disulfide
Methylene chloride
4/4
2/4
8/17
10.0
5.0
0.5 to 15.0
2.0 to 4.0
1.0 to 6.0
0.7 to 6.0
NAC
NA
NA
3.0
3.5
2.7
Inorganics (u.g/L)
Lead
Zinc
4/20
7/7
1.0 to 5.0
20.0
6.01021.0
340.0 to 3800.0
<10to 14
<3 to 38
10.05
1330.0
aData obtained from U.S. Geological Survey WATSTORE database using wells located within 10 miles of Williams AFB.
bArithmetic mean was calculated using only detected concentrations.
OK
CNA = Not available or not used for comparison.
KN/3187/WP3187.4-3/01 -22-96(9:22am)/DO/El
-------
Table 4-4
Analytical Data Summary
Southwest Drainage System (SD-09), Soils
OU-3 Rl, October - December 1993
Williams Air Force Base
(Page 1 of 2)
Compound
Frequency
of Detection3
Range of Detected
Concentrations
(mo/kg)
Base-Specific
Range for
Inorganics6
(mg/kg)
Organics: VOCs
1 ,1 ,1 -Trichloroethane
Chlorobenzene
Ethyl benzene
Toluene
Xylenes (total)
1/34
1/34
1/34
3/34
1/34
0.002 to 0.002
0.004 to 0.004
0.01 to 0.01
0.001 to 0.011
0.01 to 0.01
NAC
NA
NA
NA
NA
Organics: SVOCs
1 ,2,4-Trichlorobenzene
2-Methylnaphthalene
4-Chloro-3-methylphenol
Acenaphthene
Bis(2-ethylhexyl)phthalate
Di-n-butyl phthalate
Di-n-octyl phthalate
Diethyl phthalate
Pentachlorophenol
Pyrene
1/34
1/34
1/34
1/34
1/34
12/34
1/34
16/34
1/34
2/34
0.028 to 0.028
0.089 to 0.089
0.031 to 0.031
0.027 to 0.027
0.11 to 0.11
0.02 to 0.085
0.37 to 0.37
0.019 to 0.31
0.061 to 0.061
0.024 to 0.094
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Inorganics: Priority Pollutant Metals
Antimony
Arsenic
Beryllium
Cadmium
Chromium
2/49
34/43
28/49
18/49
49/49
8.5 to 11.1
0.46 to 5.7
0.5 to 2.2
0.95 to 6.3
15.1 to 49.8
NDd(<12)
2.3 to 4.3
1.0 to 1.6
ND(<1)
16.9 to 24.8
KN/3187/WP31 S7.4-4/01-22-96(9:23am)/DO/El
-------
Table 4-4
Analytical Data Summary
Southwest Drainage System (SD-09), Soils
OU-3 Rl, October - December 1993
Williams Air Force Base
(Page 2 of 2)
Compound
Copper
Lead
Nickel
Selenium
Silver
Zinc
Frequency
of Detection3
49/49
48/49
49/49
4/42
2/49
49/49
Range of Detected
Concentrations
(mg/kg)
7.1 to 47.8
8.6 to 297
9.5 to 31. 5
0.47 to 0.58
2.3 to 9.9
34.1 to 278
Base-Specific
Range for
Inorganics'3
(mg/kg)
ND(<5)
10.4 to 19.4
15.6 to 24.7
0.21 to 0.24
ND(<2)
ND(<4)
aRejected data not included in total number of samples.
blhe average soil concentration represents the mean of surface soil samples plus one duplicate collected
at Williams AFB in September 1993. The range represents the low and high values for the ten samples.
CNA = Not available or not used for comparison.
dND = Nondetect (value is below contract detection limit).
KN/31S7/WP3187.4-4/01-22-96(9:23am)/DO/El
-------
ORMER S
RAINAGE Dl
HOUSE NO.9553 THRU 95
VALIDATED Si
LEAD RESULT Nl
( MG/KG)
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
OIL/WATER SEPARATOR.
BLDG.
BLDG.
BLDG.
BLDG.
BLDG.
BLDG.
BLDG.
BLDG.
BLDG.
BLDG.
BLDG.
BLDG.
BLOC.
BLDG.
SD-0S-01. IN STORM DRAIN DITCH BEHIND 3LDG.
SO-09-01. IN STORM DRAIN DITCH BEHIND 3LDG.
SW STORM DRAIN
BEND IN DI TCH. S. OF HOUSINO AREA
NE CORNER OF IMPOUNDMENT AT SW END OF DITCH
SW CORNER OF IMPOUNDMENT AT SW END OF DITCH
SD-BS-eS. INTERSECTION 15TH k WASHINGTON STS.
OIL/WATER SEPARATOR. BLD 532. 2 FT BELOW BOTTOM OF IPE
OIL/WATER SEPARATOR AT BLD 532^.2 FT BELOW BOTTOM OF PIPE
OIL/WATER SEPARATOR. BLD 533. 2 FT BELOW BOTTOM OF PIPE
11 FT FROM SD01 HEAOWORKS (SCB-0I) AT STORMLINE
62 FT FROM SD05) HEftDWORKS (SCB-01) AT STORMLINE
NE OF S00<3 HEADWORKS (SCB-01) AT STORKL1 NE
H2334
H2335
H2336
H2338
H233S
H2340
H2341
H2343
H2344
H2345
H2347
H2348
H2349
H2350
H2353
H2354
H2355
H2356
H2357
H2358
H235S
H236I
H2362
H2363
H2365
H236B
H2367
EXCAVATION 1
EXCAVATION 1
STOCKP! LE
EXCAVATI ON
EXCAVATION
STOCKPILE
STOCKP:LE
STOCKPILE
EXCAVATION
EXCAVATION
STOCKPILE
STOCKPILE
RETENTION
IMPOUNDMENT
so-at-02.
SD-0<>-03.
SO- 09-04,
50-01-05.
-------
X \
JUULJUUUl^
PARKING
532
V H2362 >
innnnnnsw
H2391
H2392
H2382
H23S3
fHWEST
CH
521
SCB-15
522
NOTES:
HEADWORDS
H2366
H239S
H2397
H2398
H2399
H2400
H2401
H2402
I \ H2403
1. SAMPLES H2334, H2335. H2338.
H2339. H2343, H2344, H2346,
AND H2347 COLLECTED FROM
OWS EXCAVATIONS.
CEMENTED PORTION
OF SD-09 (REMOVED
DECEMBER 1993)
PRIMARY ROAD
DRAINAGE FLOW
FENCE
SOIL SAMPLE LOCATION &
SAMPLE ID NUMBER.
H23S3 AND H2354
2355
^SOUTHWEST DRAINAGE
SYSTEM (SD-09)
STORM SEWER MANHOLE (SMH-XX)
OIL/WATER SEPARATOR
REMOVED SEPTEMBER. 1993
STORM LINE & OWS PIPING
(REMOVED DECEMBER 1993)
a STORM SEWER CATCH BASIN
(SCB-XX)
] 532 BUILDING AND NUMBER
SCALE
fiWUt VHLIUHItU 1 1 1
UMBER
2368
2369
2370
2371
2372
2373
i2375
12376
12379
(2380
12382
12383
12384
12385
12386
12390
12391
12392
12393
12396
12397
12398
12399
12400
12401
12402
12403
H2404
DESCRIPTION
NE OF SD09 HEADWORKS (SC8-01) AT STORMUI NE
NE OF S009 HEADWORKS (SCB-01) AT STORMLI NE
NE OF SD09 HEAOWORKS (SCB-01) AT STORMLJI NE
NE OF S009 HEADWORKS (SCB-01) AT STORMLI NE
NE OF SD09 HEADWORKS 1 SCB-01 1 AT STORMLI NE
NE OF SD09 HEAOWORKS 1 SCB-01) AT STORMLI NE
STORMLI NE BETWEEN BLDG. 53 AND 533
STORMLI NE BETWEEN BLDG. 53 AND 533
STORMLI NE NEAR BLDG. 53
STORMLI NE BETWEEN BLDG. 5"* AND 533
STORMLI NE NEAR BLOG. 533
STORMLI NE NEAR BLDG. 533
STORMLI NE NEAR BLOG. 533
STORMLI NE NEAR BLOG. 533
STORMLI NE BETWEEN BLOG. 53 AND 533
STORMLI NE NEAR BLDG. 533
STORM.! NE NEAR BLOG. 533
STORMLI NE NEAR BLOG. 533
STORMLI NE BETWEEN BLDG. S 53 AND 533
SD-09 DRAINAGE 01 TCH
SD-09 DRAINAGE DITCH
SD-09 DRAINAGE DI TCH
SD-09 DRAINAGE DITCH
SD-09 DRAINAGE DI TCH
SD-09 DRAINAGE DITCH
SD-09 DRAINAGE DI TCH
SO- 09 DRAINAGE DI TCH
STORMLI NE. PIPING FROM OWS AT BLOG. 53
DEPTH
(FT)
6.0
5.5
6.0
6.0
6.5
6.0
6.5
6.0
6.0
6 0
5.5
5.5
5.5
6.0
6.5
6.0
6.0
6.0
6.0
0-0.25
0-0.25
0-0.25
0-0.25
0-0.25
0-0.25
a. 25
0-0.25
6.0
LEAD RESULT
( MG/KG)
8.
13.
11.
23.
8.
12.
10.
13.
16.
1 3
16.
10.
17.
27.
10.
31.
15.
17.
19.
70.
65.
71.
71.
63.
75.
71.
57.
11.
7
3
5
5
6
3
9
4
5
4
0
8
2
0
4
7
9
6
8
1
2
1
9
8
0
7
5
4
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
0 400 800 FEET
FIGURE 4-4
SD-09 DITCH AND STORM
LINE
LEAD CONCENTRATIONS
1993 CONFIRMATORY SAMPLING
WILLIAMS AIR FORCE BASE
J. 1 INTERNATIONAL
1 H H TECHNOLOGY
P T m CORPORATION
-------
Groundwater. Results of previous and current sampling programs at SD-09 indicate that no
extensive soil contamination exists along the length of the site. Therefore, groundwater
beneath SD-09 was not monitored because there was no evidence of a pathway to groundwa-
ter from the soils.
4.3 Contaminant Fate and Transport
Detailed discussions of contaminant fate and transport for organic and inorganic constituents
were presented in the OU-3 RI report (IT, 1994). A brief synopsis follows.
4.3.1 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 biologically 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 complexa-
tion/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/reduc-
tion potential (Eh), soil/water composition, infiltration rate, and chemical concentration.
KN/3187/WP3187.4/01-22-96(9:21«m)/DO/El 4-4
-------
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 biodegradation are all prominent processes. The behavior of 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.
4.3.2 Site-Specific Applications
A qualitative assessment of the transport potential based on chemical and physical properties,
including concentration for the organic and inorganic analytes is presented in the following
paragraphs for FT-02 and SD-09.
4.3.2.1 Fire Protection Training Area No. 2
Organic compounds detected in FT-02 soils are summarized in Table 4-2. Chemicals of
potential concern (COPC) for soil are listed in Section 5.2.3.1. Each of the COPCs were
detected at fairly deep zones at low concentrations. The fuel components BTEX were
detected more frequently and at generally higher concentrations than other compounds. The
deepest detection of a BTEX component was at 76 feet bgs, but not below this depth.
Processes such as sorption, dispersion, and biodegradation will retard the movement potential
of these organics. The activities at FT-02 have been stopped, thereby not adding any other
compounds to the soil. BTEX has not been detected in any groundwater sample collected at
FT-02.
Similar reasoning can be applied to other organic compounds detected in the soils. Com-
pounds including MEK, acetone, and dichlorobenzene have been detected at some depth but
at lower concentrations. Volatilization, sorption, degradation, and dispersion processes may
preclude other organics from reaching groundwater (depth of 215 feet bgs) at concentrations
that would exceed acceptable limits.
Inorganic analytes detected above background concentrations include cadmium, lead, and
mercury. Mercury was detected in only one sample, which appears to be an anomaly. Lead
was analyzed in soil samples collected from all FT-02 soil borings, whereas other metals were
KN/3187/WP3187.4A>l-22-96(9:21am)/DO/El 4-5
-------
only analyzed in one boring (FT02-B-01). The subsurface soil at FT-02, as at other sites at
Williams AFB contain high percentages of fine-grained sediments (silts and clays). Sorption
of these inorganics onto the silts and clays is expected to greatly reduce their vertical
migration potential.
4.3.2.2 Southwest Drainage System
Organic compounds detected at SD-09 are summarized in Table 4-4. Each compound was
detected at relatively low concentrations and at shallow depths. The more volatile compounds
were all detected at shallow depths. Below a depth of 20 feet, concentrations are very low
(generally less than 0.020 mg/kg). At these low concentrations, dispersion will result in
lower concentrations as any migration occurs. No impact to groundwater is anticipated based
on the travel depth to groundwater (200 feet) and the dispersion process.
Semivolatile organic compounds (SVOC) such as phthalates, phenol, and pyrene were also
detected between depths of 20 and 40 feet. Their physical properties such as low solubilities
and sorption potentials, coupled with the distance to groundwater and the dispersion process,
suggest that the overall impact to groundwater would be negligible or nonexistent.
Inorganic analytes were commonly detected in soil samples from SD-09. The potential for
sorption to the soil and various oxidation potentials will reduce the likelihood for migration of
metals to appreciable depths and at concentrations above background levels. Negative
impacts to groundwater are not anticipated to occur from the concentrations detected at
SD-09.
4.3.2.3 Discussion
Both FT-02 and SD-09 were in use for more than 30 years and it has been determined that
the depth of contamination is limited; at FT-02 it is less than 100 feet, and at SD-09,
approximately 40 feet. Introduction of any contaminants at either facility was sporadic in
nature so that no continuous source of contamination was present. Therefore, no saturated
conditions from the ground surface to the water table was likely to have ever existed.
FT-02 has been removed from use and any sources that could have contributed contaminants
through SD-09 are no longer in service. No additional sources will be added to the subsur-
face through these two areas. The lack of additional sources and the absence of a saturated
column will be the greatest inhibitors to any future downward migration of chemicals.
Additional factors that will preclude migration are dispersion of chemicals, adsorption to the
KN/3187/WP31S7.4/01-22-96(921am)/DO/El 4-6
-------
soil matrix and organic matter, biodegradation and biotransformation. Migration will cause a
redistribution of contaminants and because concentrations are presently relatively small,
concentrations will continue to decrease with any movement, as some will remain fixed on
the soil profile or within pore spaces.
KN/3187AVP3187.4/Dl-22-96(921am)/DO/El 4-7
-------
-------
5.0 Summary of Potential Site Risks
5.1 Introduction
This chapter summarizes the baseline risk assessment and the identification of chemicals
requiring remedial action for FT-02 and SD-09, which have been designated as part of OU-3.
The risk assessment and the identification of chemicals for remedial action were performed as
part of the RI/FS initiated by the USAF under the IRP. The details of the risk assessment
and identification of chemicals for remedial action are outlined in, respectively, Chapter 6.0
of the OU-3 RI report (IT, 1994), and Chapter 2.0 of the OU-3 FS report (IT, 1995). The
objective of this summary is to provide information to support the decision for a remedial
action, or alternatively, for the no-further-action alternative. The risk assessment was
conducted in accordance with the guidance documents: Risk Assessment Guidance for
Superfund, Human Health Evaluation Manual, Part A, Interim Final (EPA, 1989a) and Risk
Assessment Guidance for Superfund, Human Health Risk Assessment: EPA Region IX
Recommendations (EPA, 1989b).
5.2 Identification of Chemicals of Potential Concern
Data collected during the RI were evaluated for use in the risk assessment in accordance with
EPA guidelines. This process included evaluating the sample collection and analytical
methods used, evaluating the quality of the data, and comparing data to background. The
purpose of this selection process is to first identify those chemicals potentially harmful to
human health if present at the site, identify those chemicals that are likely to be site-related
and lastly, to evaluate the acceptability of the analytical data to be used in the quantitative
risk assessment (EPA, 1989a). Some chemicals found during the sampling effort were
eliminated from the list of COPCs based on the following criteria as recommended by the
EPA (1989a,b):
Frequency Of Detection: Chemicals 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. All remaining
chemicals were evaluated for possible health effects.
Background: Chemicals were eliminated from consideration if the range of
the site-influenced values was within the range of Base-specific background
values and the 95 percent upper confidence limit of the arithmetic mean concen-
tration was below the appropriate EPA Region DC Preliminary Remediation Goal
(PRO).
KN/3187/WP3187.5/01-22-96(9:23am)/DO/El 5-1
-------
Chemical Specificity: Chemicals were eliminated if they represented analyti-
cal results that were not specific for a particular compound (e.g., gross alpha,
gross beta, TPH).
All inorganic chemicals were compared to Base-specific background ranges. All inorganics
were selected as COPCs because site-related concentrations generally exceeded background
concentrations.
The following sections present COPCs in soils and groundwater, by site. Groundwater from
SD-09 was not sampled.
This evaluation and selection process is discussed in greater detail in Section 6.2 of the OU-3
RI report (EPA, 1994).
5.2.1 Chemicals of Potential Concern for Groundwater
5.2.1.1 Fire Protection Training Area No. 2
The effective precipitation for this area is small or nonexistent (Section 3.2, OU-3 RI report),
minimizing the likelihood that infiltration from natural precipitation would transport chemicals
to groundwater. The FT-02 area, however, was subjected to water application over a small
surface area during the fire training exercises. This water could increase the likelihood of the
downward transport of chemicals; therefore, groundwater beneath FT-02 was sampled.
Chemicals detected in groundwater samples from FT-02 are listed in Table 5-1. All chemi-
cals detected within FT-02 were selected as COPCs. The five COPCs for FT-02 are:
Acetone Lead Zinc
Carbon disulfide Methylene chloride
5.2.1.2 Southwest Drainage System
The groundwater beneath SD-09 was not sampled because soils data collected during previous
investigations indicate that there are no significant concentrations of chemicals present in the
deep soils and, consequently, it is unlikely that groundwater is affected (Section 5.4.3, OU-3
RI report). In addition, the effective precipitation for the area is small or nonexistent,
indicating that infiltration is an unlikely mechanism to transport soil contaminants to
groundwater.
KN/3187/WP3187.5/01-22-96{9:23am)/DO/El 5-2
-------
Table 5-1
Analytical Data Summary
Fire Protection Training Area No. 2 (FT-02), Ground water
Williams Air Force Base
Analyte
Frequency
of
Detection
Range of
Detection
Limits
(H9/L)
Range of
Detected
Concentrations
(W/L)
Regional
Background
Range3
(MQ/L)
UCL 95%
Concentration
(MO/L)
Organics
*Acetone
*Carbon disulfide
*Methylene chloride
4/4
2/4
8/13
10.0
5.0
0.5 to 5.0
2.0 to 4.0
1.0 to 6.0
0.7 to 6.0
NAb
NA
NA
4.3
6.4
2.9
Inorganics
*Lead
*Zinc
3/16
7/7
1.0 to 5.0
20.0
6.0 to 21.0
340.0 to 3800.0
<10to 14
<3to38
6.5
2500.0
aData obtained from U.S. Geological Survey WATSTORE database using wells tocated wrthin 10 miles
of Williams AFB.
bNA - Not available or not used for comparison.
* Chemical of potential concern.
KN/3187AVP31875-lA)l-22-96(9:24am)/DO/El
-------
5.2.2 Chemicals of Potential Concern for Soils
5.2.2.1 Fire Protection Training Area No. 2
Chemicals detected in soil samples from FT-02 are listed in Table 5-2.
The COPCs for soil in FT-02 are:
1,2-Dichlorobenzene Cadmium
1,4-Dichlorobenzene Copper
Acetone Chromium
Benzene Lead
Chloroform Mercury
Ethyl benzene Nickel
Bis(2-ethylhexyl)phthalate Zinc
Methylene chloride
Methyl ethyl ketone
Toluene
Xylenes
5.2.2.2 Southwest Drainage System
Chemicals detected in soil samples from SD-09 are listed in Tables 5-3 (surface soil) and 5-4
(subsurface soil). Chromium analytical data, and data analysis, have been updated since the
release of the OU-3 RI report; thus, chromium data presented in Table 5-3 reflect the most
recent values, and differ from those presented in the OU-3 RI report. The COPCs for soil in
SD-09 are:
1,1,1-Trichloroethane Antimony
Acetone Arsenic
Bis(2-ethylhexyl)phthalate Beryllium
Di-n-butyl phthalate Cadmium
Diethyl phthalate Chromium
Ethyl Alcohol Copper
Methylene Chloride Lead
Phenol Nickel
Pyrene Mercury
Toluene Selenium
Silver
Thallium
Zinc.
KN/3187/WP3187.5A>l-22-96(9:23am)/DO/El 5~3
-------
Table 5-2
Analytical Data Summary
Fire Protection Training Area No. 2 (FT-02), Soils
Williams Air Force Base
(Page 1 of 2)
Analyte
Frequency of
Detection
Value or Range
of Detection
Limits
(mg/kg)
Value or Range
of Detected
Concentrations
(mg/kg)
Base-Specific
Range of
Background8
(mg/kg)
UCL
Concentration
(mg/kg)
Reason for Exclusion
Organlcs
*1 ,2-Dichlorobenzene
1,3-Dichlorobenzene
1 ,4-Dichlorobenzene
Acetone
Benzene
*Bis(2-ethylhexyl)phthalate
Chlorobenzene
Chloroform
Ethyl benzene
Methyl ethyl ketone
Methylene chloride
Toluene
Xylenes
14/73
5/114
19/73
2/2
15/73
2/2
1/114
3/43
24/73
13/42
19/43
17/73
25/73
0.36 to 1.0
0.36 to 1.0
0.36 to 1.0
0.011 to 0.01 2
0.005 to 2.0
0.36 to 0.39
0.005 to 1.0
0.005 to 1.0
0.005 to 1.0
0.011 to 10
0.005 to 1.0
0.005 to 2.0
0.005 to 2.0
0.36 to 23
0.36 to 47
0.36 to 56
0.01 to 0.02
0.01 to 83
0.19 to 1.2
0.01 to 5.0
0.01 to 2.0
0.01 to 63
0.01 to 610
0.04 to 8
0.01 to 130
0.01 to 240
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
4.03
2.25
8.23
0.017
7.32
1.39
0.61
0.66
6.64
111.87
3.04
9.41
27.36
NR
Frequency of detection is £ 5%
NR
NR
NR
NR
Frequency of detection is £ 5%
NR
NR
NR
NR
NR
NR
Inorganics
"Cadmium
Chromium
1/2
2/2
2.0
3.0
2.0 to 4.0
14 to 16
ND(<1)
16.9 to 24.8
4.58
16.38
NR
NR
KN/3187/WP3187.5-2/01-22-96(9:25am)/DO/E1
-------
Table 5-2
Analytical Data Summary
Fire Protection Training Area No. 2 (FT-02), Soils
Williams Air Force Base
(Page 2 of 2)
Analyte
'Copper
Lead
'Mercury
'Nickel
Zinc
Frequency of
Detection
2/2
133/144
1/2
2/2
2/2
Value or Range
of Detection
Limits
(mg/kg)
6.0 to 7.0
0.7 to 10
0.3
9.0 to 10
5.0
Value or Range
of Detected
Concentrations
(mg/kg)
20
4.0 to 70
0.08 to 5.9
13 to 17
51 to 60
Base-Specific
Range of
Background9
(mg/kg)
ND (<5)
10.4 to 19.4
ND (<0.2)
15.6 to 24.7
ND (<4)
UCL
Concentration
(fig/kg)
20
17.99
7.01
17.77
61.74
Reason for Exclusion
NR
NR
NR
NR
NR
a The average soil concentration represents the mean of nine surface soil samples plus one duplicate collected at Williams AFB in September 1993. The range represents the low
and high value for the ten samples.
* Chemical of potential concern.
NA = Not available or not used for comparison.
ND = Not detected.
NR = Not relevant.
KN/3187/WP3187.5-2/01 -22-96(9:25am)/DO/E 1
-------
Table 5-3
Analytical Data Summary
Southwest Drainage System (SD-09), Surface Soils
Williams Air Force Base
(Page 1 of 3)
Analyte
Frequency
of
Detection
Value or Range
of Detection
Limits
(mg/kg)
Value or
Range of
Detected
Concentration
(mg/kg)
Base-
Specific8
Range of
Background
(mg/kg)
UCL
Concentration
(mg/kg)
Reason for Exclusion
Organ Ics
*1 , 1 , 1 -Trichloroethane
2-Butanone
4-Methyl-2-pentanone
"Acetone
Benzo(b)fluoranthene
*Bis(2-ethylhexyl)phthalate
Butyl benzyl phthalate
Di-n-octyl phthalate
*Diethyl phthalate
Dimethyl phthalate
*Ethyl alcohol
4/41
1/45
1/41
4/10
1/10
6/10
1/10
1/10
2/10
1/10
1/31
0.005 to 0.01
0.005 to 0.01 2
0.01 to 0.05
0.01 to 0.012
0.33 to 0.39
0.33 to 0.39
0.33 to 0.39
0.33 to 0.39
0.33 to 0.39
0.33 to 0.39
0.05
0 to 0.01 2
0 to 0.01 6
0 to 0.01 2
0.011 to 0.21
0 to 0.38
0.02 to 3
0 to 0.38
0 to 0.39
0 to 0.39
0 to 0.39
0 to 0.11
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.004
0.022
0.023
0.083
0.19
1.037
0.189
0.186
0.185
0.188
0.033
NR
Frequency of detection < 5% when
combined with subsurface soil samples
Frequency of detection £ 5% when
combined with subsurface soil samples
NR
Frequency of detection <, 5% when
combined with subsurface soil samples
NR
Frequency of detection £ 5% when
combined with subsurface soil samples
Frequency of detection < 5% when
combined with subsurface soil samples
NR
Frequency of detection < 5% when
combined with subsurface soil samples
NR
KN/3187/WP3187.5-3/01-22-96(9:25am)/DO/El
-------
Table 5-3
Analytical Data Summary
Southwest Drainage System (SD-09), Surface Soils
Williams Air Force Base
(Page 2 of 3)
Analyte
Fluoranthene
*Methylene chloride
Oil and Grease
*Pheno!
*Pyrene
*Toluene
Total organic halogens
Total petroleum
hydrocarbons
Frequency
of
Detection
1/10
4/10
2/4
1/14
1/10
4/44
3/4
4/4
Value or Range
of Detection
Limits
(mg/kg)
0.33 to 0.39
0.005 to 0.01
50
0.33 to 0.5
0.33 to 0.39
0.005 to 0.01
1
2
Value or
Range of
Detected
Concentration
(mg/kg)
0 to 0.39
0.011 to 0.1 3
0 to 100
Oto 1.1
0 to 0.38
Oto 0.01 2
Oto 7
3 to 49
Base-
Specific8
Range of
Background
(mg/kg)
NA
NA
NA
NA
NA
NA
NA
NA
UCL
Concentration
(mg/kg)
0.183
0.055
99.25
0.38
0.187
0.003
4.999
34.48
Reason for Exclusion
Frequency of detection £ 5% when
combined with subsurface soil samples
NR
Chemical specificity
NR
NR
NR
Chemical specificity
Chemical specificity
Inorganics
*Antimony
*Arsenic
*Beryllium
*Cadmium
* Chromium
5/16
10/18
19/25
25/31
28/28
12
2 to 3
1 to 2
0.2 to 2
2 to 5
1 1 to 68
Oto 5
0 to 2.2
Oto 90
17.6 to 49.8
ND (<12)
2.3 to 4.3
1.0 to 1.6
ND(<1)
16.9 to 24.8
30.2
2.5
1.22
12.39
33.2
NR
NR
NR
NR
NR
KN/3187/WP3187.5-3/01-22-96(9:25am)/DO/El
-------
Table 5-3
Analytical Data Summary
Southwest Drainage System (SD-09), Surface Soils
Williams Air Force Base
(Page 3 of 3)
Analyte
*Copper
"Lead
*Mercury
*Nickel
*Selenium
*Silver
*Thallium
*Zinc
Frequency
of
Detection
29/29
28/28
2125
25/25
4/18
4/25
2/18
25/25
Value or Range
of Detection
Limits
(mg/kg)
0.4 to 5
0.6 to 2
0.2
8
1 to 2
2 to 3
2 to 3
4
Value or
Range of
Detected
Concentration
(mg/kg)
14.1 to 47.8
10.9 to 96
Oto.19
13.2 to 31 .5
0 to 0.58
Oto13
0 to 0.9
52 to 278
Base-
Specific8
Range of
Background
(mg/kg)
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)
UCL
Concentration
(mg/kg)
33.32
53.39
0.11
25.8
0.675
2.52
1.149
152.522
Reason for Exclusion
NR
NR
NR
NR
NR
NR
NR
NR
"The average soil concentration represents the mean of nine surface soil samples plus one duplicate collected at Williams AFB on September 1993. The range
presents the low and high values for the ten samples.
bUpdated values, differing from value reported in Chapter 6 of OU-3 Rl (see section 5.2.3.2)
* Chemical of potential concern.
NA = Not available.
ND = Not detected.
NR = Not relevant.
KN/3187/WP3187.5-3/01-22-96(9:25am)/DO/El
-------
Table 5-4
Analytical Data Summary
Southwest Drainage System (SD-09), Subsurface Soils
Williams Air Force Base
(Page 1 of 2)
Analyte
Frequency
of
Detection
Value or Range
of Detection
Limits
(mg/kg)
Value or Range
of Detected
Concentration
(mg/kg)
Base-Specific8
Range of
Background
(mg/kg)
UCL
Concentration
(mg/kg)
Reason for Exclusion
Organlcs
*1,1,1-Trichloroethane
1 ,2,4-Trichlorobenzene
2-Methylnaphthalene
4-Chloro-3-methylphenol
Acenaphthene
'Acetone
Benzene
*Bis(2-ethylhexyl)phthalate
Bromodichloromethane
Butyl benzyl phthalate
Chlorobenzene
*Di-n-butyl phthalate
*Diethyl phthalate
*Ethyl alcohol
Ethyl benzene
*Methylene chloride
Oil and Grease
Pentachlorophenol
*Phenol
*Pyrene
1/82
1/51
1/51
1/51
1/51
16/51
1/86
16/51
1/83
1/51
1/118
13/51
17/51
5/32
1/86
17/51
1/4
1/51
8/55
2/51
0.005 to 0.013
0.33to1.7
0.33 to 1.7
0.33 to 1.7
0.33 to 1.7
0.01 to 0.025
0.005 to 0.013
0.33to1.7
0.005 to 0.013
0.33to1.7
0.005 to 0.01 3
0.33to1.7
0.33to1.7
0.05
0.005 to 0.013
0.005 to 0.013
50
0.8 to 8
0.33 to 1 .7
0.33 to 1.7
0 to 0.01 2
0 to 0.41
0 to 0.41
0 to 0.41
0 to 0.41
0 to 0.032
0 to 0.012
Oto18
0 to 0.01 2
0 to 0.41
0 to 0.01 2
0 to 0.4
0 to 0.41
0 to 0.11
0 to 0.01 2
0.005 to 0.11
0 to 130
Oto1
Oto 1
0 to 0.41
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.004
0.300
0.291
0.300
0.300
0.005
0.004
4.23
0.004
0.29
0.004
0.265
0.27
0.042
0.004
0.009
95.81
1.17
0.29
0.289
NR
Frequency of detection £ 5%
Frequency of detection £ 5%
Frequency of detection s 5%
Frequency of detection £ 5%
NR
Frequency of detection £ 5%
NR
Frequency of detection £ 5%
Frequency of detection <, 5%
Frequency of detection £ 5%
NR
NR
NR
Frequency of detection £ 5%
NR
Chemical specificity
Frequency of detection <, 5%
NR
NR
KN/3187/WP3187.5-4/01-22-96(9:26am)/DO/El
-------
Table 5-4
Analytical Data Summary
Southwest Drainage System (SD-09), Subsurface Soils
Williams Air Force Base
(Page 2 of 2)
Analyte
*Toluene
Total petroleum hydrocarbons
Xylenes (total)
Frequency
of
Detection
5/86
10/15
1/86
Value or Range
of Detection
Limits
(mg/kg)
0.005 to 0.013
2
0.005 to 0.01 3
Value or Range
of Detected
Concentration
(mg/kg)
0 to 0.01 2
Oto20
0 to 0.01 2
Base-Specific8
Range of
Background
(mg/kg)
NA
NA
NA
UCL
Concentration
(mg/kg)
0.004
8.71
0.004
Reason for Exclusion
NR
Chemical specificity
Frequency of detection £ 5%
Inorganics
'Antimony
*Arsenic
'Beryllium
*Cadmium
*Chromium
'Copper
*Lead
*Nickel
'Silver
'Thallium
'Zinc
15/34
42/52
16/51
7/55
57/57
54/55
54/55
51/51
2/51
1/51
51/51
12 to 20
2 to 5
1 to 3
0.2 to 3
2 to 5
0.4 to 6
0.6 to 2
8
2 to 5
2 to 30
4
Oto46
0 to 5.7
0 to 2.1
0 to 6.3
12 to 53
Oto61
8 to 87.4
9 to 25.9
0 to 9.9
0 to 0.95
28 to 233
ND (<12)
2.3 to 4.3
1.0to1.6
ND (<1)
16.9 to 24.8
ND (<5)
10.4 to 19.4
15.6 to 24.7
ND (<2)
ND (<2)
ND (<4)
21.64
2.52
0.78
1.08
21.77
19.15
22.87
18.09
1.62
3.45
64.8
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
aThe average soil concentration represents the mean of nine surface soil samples plus one duplicate collected at Williams AFB in September 1993. The range presents the low and
high value for the ten samples.
* Chemical of potential concern.
NA = Not available or not used for comparison.
ND = Not detected.
NR = Not relevant.
KN/3187/WP3187.5-4/01 -22-96(9:26am)/DO/E 1
-------
5.2.3 Uncertainties
Uncertainties associated with the collection and laboratory analysis of the sampling data may
impact the results of the selection process. These uncertainties result from the possible
contamination of samples during collection, preparation, or analysis, and normal variation in
the analytical techniques and could result in over- or underestimation of contaminant
concentrations. These uncertainties are minimized by the laboratory validation process.
5.3 Exposure Assessment
This section presents the estimation of potential exposures of human or environmental recep-
tors to chemicals 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, 1989a):
Characterization of exposure setting
Identification of potential exposure pathways
Quantification of exposure (where possible).
5.3.1 Receptor Assessment
The objective of the receptor assessment is to identify potential human and environmental
populations that may be exposed to site-related chemicals at the Base under current and future
land-use conditions. The assessment considers both on- and off-Base populations and their
relationship to the potential migration pathways for site-related chemicals.
On-Base Land Use. The Base is relatively small when compared to most USAF bases. It
was closed on September 30, 1993 and transitioned from the Air Force's ATC to the Air
Force Base Conversion Agency. This agency is working with the local community through
the RAB and the Williams Redevelopment Partnership. The Partnership will maximize reuse
for aviation, education, commercial, and industrial uses. The Base has been divided into
potential reuse parcels identified as airfield, commercial, aviation support, air cargo, general
industrial, education/research/training, institutional/medical, and schools. The golf course has
been leased. Leases are being negotiated for several industrial areas. Universities are also
considering establishing portions of their campuses at the Base. Because the Base is closed,
land use at the site could become residential, commercial, and/or agricultural.
KN/3187/WP3187.5/01-22-96{9:23am)/DO/El 5-4
-------
There are two categories of potential receptors: (1) occupational receptors are those poten-
tially exposed as a result of activities associated with duty assignments; (2) residential re-
ceptors are those potentially exposed as a result of living on the Base. The Base is fenced,
with security guards at the entrance, and is currently inaccessible to off-Base populations.
Future exposures to residential receptors will also be considered under the assumption that the
Base property will be developed for residential purposes now that the Base has closed. It is
assumed that future residential populations will also include sensitive subpopulations such as
infants, children, elderly persons, and pregnant and nursing women.
Off-Base Land Use. The Base is relatively isolated from any large metropolitan area.
Located in Maricopa County, it is surrounded mostly by agricultural land, which has had a
long history of intensive uses, predominantly production of citrus, cotton, and alfalfa. Smaller
urban areas such as the City of Mesa, the Town of Gilbert, and the City of Apache Junction
are located 5 to 15 miles northeast and northwest of the Base (Section 3.7.2, OU-3 RI report).
5.3.2 Identification of Potential Exposure Pathways
For exposures to occur, complete exposure pathways must exist A complete exposure path-
way requires (EPA, 1989a):
A source and mechanism for release of the chemical
An environmental transport pathway
A point of potential human contact
An exposure route at the exposure point
If any one of these four components is absent, then an exposure pathway is incomplete. The
conceptual exposure model for OU-3, providing a visual overview of all the potential
exposure pathways considered here, is presented in Figure 5-1. The following sections
describe the potential exposure pathways for each of the OU-3 sites evaluated at the Base.
5.3.2.1 Fire Protection Training Area No. 2
All potential pathways included in the risk assessment for current and future land use, off-
and on-base, are summarized in Table 5-5.
5.3.2.2 Southwest Drainage System
All potential pathways included in the risk assessment for current an future land use, off- and
on-base, are summarized in Table 5-6.
KN/3187AVP31875A)l-22-96(923am)/DO/El 5-5
-------
F
1
!
:
5
i
< 91
i-8
II
5° S"
1
T
1
6 I
-~ sf
< K
o ?
5§
^v
-^
^1-
,
]
1
,
,
i
*
S
SJ_
a
4k
CQ
O
P
,
?
M
>
f
1
M
O
B
4k
o
§
o>
O
P
£
ff
s
I
S- 5
11
f|
I
1
i?
ar
7
S"
B
0
n
s>
i
M
?
O
5*
1
^
S"
Kl
w
w
W
Occupational
Residential
Occupational
Residential
£i
o
en
H
0
2x
§3
:XPOSU
ROUTE
M
33
^
ff
S
= SL
I* 5
1-8 a
> S ««
W 2.
S?
1
-------
Table 5-5
Summary of Potential Exposure Pathways
Fire Protection Area No. 2 (FT-02)
Williams Air Force Base
(Page 1 of 3)
Potentially Exposed
Populations
Exposure Pathway
Inclusion in
Risk
Assessment
Reason for Selection or
Exclusion
CURRENT LAND USE
Groundwater
Base Residents/Base
Workers
Base Residents/Base
Workers
Base Residents/Base
Workers
Base Residents
Ingestion of groundwater
from downgradient wells
Inhalation of chemicals
volatilized from water
during home use
Dermal contact with
chemicals in water during
home use
Ingestion of vegetables
contaminated by irrigation
No
No
No
No
There are currently no production
wells in the contaminated area.
No route for exposure exists.
There are currently no production
wells in the contaminated area.
No route for exposure exists.
There are currently no production
wells in the contaminated area.
No route for exposure exists.
There are currently no production
wells in the contaminated area.
No route for exposure exists.
Soil
Base Residents
Base Residents
Base Residents
Base Residents
Base Residents
Base Workers
Base Workers
Base Workers
Base Workers
Incidental ingestion of soil
Dermal contact with soil
Inhalation of chemicals
volatilized from the soil
Inhalation of fugitive dust
Ingestion of vegetables
grown on contaminated soil
Incidental ingestion of soil
Dermal contact with soil
Inhalation of chemicals
volatilized from the soil
Inhalation of fugitive dust
No
No
No
No
No
Yes
Yes
Yes
Yes
Currently there are no residents
that have access to area soils.
Currently there are no residents
that have access to area soils.
Currently there are no residents
that have access to area soils.
Currently there are no residents
that have access to area soils.
Currently there are no residents
that have access to area soils.
Workers may be potentially
exposed during soil-moving or
other activities in the area.
Base workers may be potentially
exposed during soil-moving or
other activities in the area.
Base workers may be potentially
exposed during soil-moving or
other activities in the area.
Base workers may be potentially
exposed during soil-moving or
other activities in the area.
KN/3187/WP31873-5A)l-22-96(9:2&mi)/DO/El
-------
Table 5-5
Summary of Potential Exposure Pathways
Fire Protection Area No. 2 (FT-02)
Williams Air Force Base
(Page 2 of 3)
Potentially Exposed
Populations
Exposure Pathway
Inclusion in
Risk
Assessment
Reason for Selection or
Exclusbn
FUTURE LAND USE
Groundwater
Residents
Residents
Residents
Residents
Ingestion of groundwater
from downgradient wells
Inhalation of chemicals
volatilized from water
during home use
Dermal contact with
chemicals in water during
home use
Ingestion of vegetables
contaminated by irrigation
Yes
Yes
Yes
Yes
(Qualitative)
Application of water during fire
training exercises could have
leached constituents to ground-
water. The construction of a
production well in this area would
enable contact with the water.
Application of water during fire
training exercises could have
leached constituents to ground-
water. The construction of a
production well in this area would
enable contact with the water.
Application of water during fire
training exercises could have
leached constituents to ground-
water. The construction of a
production well in this area would
enable contact with the water.
Application of water during fire
training exercises could have
leached constituents to ground-
water. The construction of a
production well in this area would
enable contact with the water.
Soil
Residents
Residents
Incidental ingestion of soil
Dermal contact with soil
Yes
Yes
There is the potential for
residential devebpment of the
Base property after closure.
Therefore, contact with the soil
will be possible.
There is the potential for
residential development of the
Base property after closure.
Therefore, contact with the soil
will be possible.
KN/3187/WP3187.5-5/01-22-96(9:26am)/DO/El
-------
Table 5-5
Summary of Potential Exposure Pathways
Fire Protection Area No. 2 (FT-02)
Williams Air Force Base
(Page 3 of 3)
Potentially Exposed
Populations
Residents
Residents
Residents
Exposure Pathway
Inhalation of chemicals
volatilized from the soil
Inhalation of fugitive dust
Ingestion of homegrown
vegetables
Inclusion in
Risk
Assessment
Yes
Yes
Yes
(Qualitative)
Reason for Selection or
Exclusion
There is the potential for
residential development of the
Base property after closure. Low
levels of volatiles were detected
in soil. Increased disturbance of
son may result in exposure.
There is the potential for
residential development of the
Base property after closure. Low
levels of chemicals of potential
concern were identified.
Increased disturbance of soil may
result in exposure.
There is the potential for
residential development of the
Base property after closure.
Therefore, contact with the soil
will be possible.
KN/3187/WP31875-5/01-22-96(9:26»m)/DO/El
-------
Table 5-6
Summary of Potential Exposure Pathways
Southwest Drainage System (SD-09)
Williams Air Force Base
(Page 1 of 3)
Potentially Exposed
Populations
Exposure Pathway
Inclusion in
Risk
Assessment
Reason for Selection or
Exclusion
CURRENT LAND USE
Groundwater
Base Residents/Base
Workers
Base Residents/Base
Workers
Base Residents/Base
Workers
Base Residents
Ingestion of groundwater
from downgradient wells
Inhalation of chemicals
volatilized from water
during home use
Dermal contact with chemi-
cals in water during home
use
Ingestion of vegetables
contaminated by irrigatbn
No
No
No
No
There are currently no produc-
tion wells in the contaminated
area. No route for exposure
exists.
There are currently no produc-
tion wells in the contaminated
area. No route for exposure
exists.
There are currently no produc-
tion wells in the contaminated
area. No route for exposure
exists.
There are currently no pro-
duction wells in the contami-
nated area. No route for
exposure exists.
Soil
Base Residents
(Children)
Base Residents
(Children)
Base Residents
(Children)
Base Residents
(Children)
incidental ingestion of soil
Dermal contact with soil
Inhalation of chemicals
volatilized from the soil
Inhalation of fugitive dusts
Yes
Yes
Yes
Yes
Children may be potentially
exposed due to accessibility and
proximity of the area to Base
housing.
Children may be potentially
exposed due to accessibility and
proximity of the area to Base
housing.
Children may be potentially
exposed due to accessibility and
proximity of the area to Base
housing.
Children may be potentially
exposed due to accessibility and
proximity of the area to Base
housing.
KN/3187/WP3187^-6/01-22-96(9:27ajn)/IX)/El
-------
Table 5-6
Summary of Potential Exposure Pathways
Southwest Drainage System (SD-09)
Williams Air Force Base
(Page 2 of 3)
Potentially Exposed
Populations
Base Workers
Base Workers
Base Workers
Base Workers
Exposure Pathway
Incidental ingestion of soil
Dermal contact with soil
Inhalation of chemicals
volatilized from the soil
Inhalation of fugitive dust
Inclusion in
Risk
Assessment
Yes
Yes
Yes
Yes
Reason for Selection or
Exclusion
Workers may be potentially
exposed during soil-moving or
other activities in the area.
Workers may be potentially
exposed during soil-moving or
other activities in the area.
Workers may be potentially
exposed during soil-moving or
other activities in the area.
Workers may be potentially
exposed during soil-moving or
other activities in the area.
FUTURE LAND USE
Groundwater
Residents
Residents
Residents
Residents
Ingestion of groundwater
from downgradient wells
Inhalation of chemicals
volatilized from water
during home use
Dermal contact with chemi-
cals in water during home
use
Ingestion of vegetables
contaminated by irrigation
No
No
No
No
Transport of chemicals from the
soil to the groundwater is not
expected. Therefore, the
exposure route is not expected
to be complete.
Transport of chemicals from the
soil to the groundwater is not
expected. Therefore, the
exposure route is not expected
to be complete.
Transport of chemicals from the
soil to the groundwater is not
expected. Therefore, the
exposure route is not expected
to be complete.
Transport of chemicals from the
soil to the groundwater is not
expected. Therefore, the
exposure route is not expected
to be complete.
KN/3187/WP3187.5-6/01-22-96(9:27im)/DO/El
-------
Table 5-6
Summary of Potential Exposure Pathways
Southwest Drainage System (SD-09)
Williams Air Force Base
(Page 3 of 3)
Potentially Exposed
Populations
Exposure Pathway
Inclusion in
Risk
Assessment
Reason for Selection or
Exclusion
Soil
Residents
Residents
Residents
Residents
Residents
Incidental ingestion of soil
Dermal contact with soil
Inhalation of chemicals
volatilized from the soil
Inhalation of fugitive dust
Ingestion of homegrown
vegetables
Yes
Yes
Yes
Yes
Yes (Qualita-
tive)
There is the potential for
residential development of the
Base property after closure.
Therefore, contact with the soil
will be possible.
There is the potential for
residential development of the
Base property after closure.
Therefore, contact with the soil
will be possible.
There is the potential for
residential development of the
Base property after closure.
Increased disturbance of soil
may result in exposure.
There is the potential for
residential development of the
Base property after closure.
Increased disturbance of soil
may result in exposure.
There is the potential for
residential development of the
Base property after closure.
Therefore, contact with the soil
will be possible.
KN/3187/WP3187.5-6A>l-22-9«(9:27am)/DO/El
-------
5.3.2.3 Ingestion of Homegrown Fruits and Vegetables
Potential risk associated with the ingestion of homegrown fruits or vegetables irrigated with
groundwater and grown in site soil was evaluated qualitatively because it was concluded
(Section 6.3.2.3, OU-3 RI report) that it is unlikely that the Base would be used for
agricultural purposes.
5.3.3 Estimation of Exposure
This section describes the concentration estimation of individual site-related COCs that may
reach human receptors. The process involves:
Identifying applicable human exposure models and input parameters
Determining the concentration of each chemical in the identified environmental
medium at the point of human exposure
Estimating human intakes.
The methodologies and parameter values that will be used to quantitatively estimate chemical
intakes for the risk assessment are presented in the following sections. In general, the
magnitude of chemical intake depends on the exposure pathway and the variables that impact
the transmittal of chemicals via that pathway. These intake estimates will be used in
conjunction with chemical toxicity data to quantify the risks associated with each pathway.
For each identified pathway, a reasonable maximum exposure (RME) scenario has been
developed. This scenario gives a reasonable upper-bound estimate of the potential magnitude
of an individual exposure to chemicals from the site. The intent of the RME as defined by
the EPA (1989a; 1991a) is to estimate a conservative exposure case (i.e., well above the
average case) that is still within the range of possible exposures. This RME approach
replaces the previous EPA recommendation for evaluating both an average and worst-case
scenario. The RME is estimated from a combination of average and upper-bound exposure
assumptions to result in a reasonable maximum.
5.3.3.1 Exposure Models
The primary source for the exposure models used for this risk assessment is the Risk Assess-
ment Guidance for Superfund, Human Health Evaluation Manual, Part A, Interim Final
(EPA, 1989a). The magnitude of chemical intake via the following exposure pathways is
estimated by exposure models presented in detail in the RI report:
KN/3187/WP3187.5/01-22-96(9:23«m)/DO/El 5-6
-------
Ingestion of drinking water
Incidental ingestion of soil
Inhalation of fugitive dust or vapor phase organic compounds in soil
Inhalation of chemicals in indoor air due to volatilization from groundwater
Dermal contact with soil and water.
5.3.3.2 Exposure Parameters
A combination of RME and average exposure parameters has been used in each scenario to
result in a combined RME. The exposure parameters used and whether they are average or
upper-bound values are summarized in Table 5-7. Upper-bound values are generally 90th or
95th percentile values depending on availability for that parameter.
5.3.3.3 Exposure-Point Concentrations
The exposure-point concentration is the concentration of a chemical in an exposure medium
that may be contacted by a receptor. Determination of the exposure-point concentration
depends on factors such as:
Availability of data from which an exposure-point concentration can be deter-
mined
Statistical methodologies selected to determine the appropriate exposure-point
concentration
Potential contributions to chemical concentrations not attributed to the site
Contamination release and transport factors
Location of potential receptors.
Exposure concentrations for the COPCs in groundwater, soil, and air are listed in Tables 5-8
and 5-9 for the Fire Protection Training Area No. 2 and Southwest Drainage System,
respectively. A description of the approach used to estimate exposure concentrations is given
in the following paragraphs.
Groundwater. To estimate the potential risks associated with completing a production well
on the Base property, the upper 95th percent confidence limit of the arithmetic mean of the
monitoring data for each COPCs was used as the value to represent the RME concentration.
For samples with no detectable concentration of a chemical, a value of one-half the contract-
required detection limit (CRDL) was used as recommended by EPA (1989a) guidance.
KN/3187/WP3187.5/01-22-96<9:23am)/DO/El 5-7
-------
Table 5-7
Parameters Used to Estimate Exposure
Williams Air Force Base
(Page 1 of 5)
Parameter
Range
Value Used
Rationale
Residential Exposure: Ingestlon of Groundwater from New Wells
Adult Water Ingestion Rate (LVday)
Exposure Frequency (days/year)
Exposure Duration (years)
Body Weight (kg)
Averaging Time for Noncarcinogenic Effects (days)
Averaging Time for Carcinogenic Effects (days)
1.4 Average
2 90th Percentile
350 Reasonable
365 Worst-Case
9 Average
30 90th Percentile
2
350
30
70
10,950
25.550
Standard exposure factor (EPA, 1 991 a)
Parameter accounts for time spent away from home (EPA, 1991 a)
Upper 90th percentile for time spent in one residence (EPA, 1991 a)
Standard exposure factor (EPA, 1989a)
30 years x 365 days/years - 10,950 days (EPA, 1989a)
70 years x 365 days/year » 25,550 days (EPA, 1989a)
Residential Exposure: Inhalation of Volatile Organic Compounds during Home Water Use (Water from New Wells)
Adult Inhalation Rate (m3/day)
Exposure Frequency (days/year)
Exposure Duration (years)
Body Weight (kg)
Averaging Time for Noncarcinogenic Effects (days)
Averaging time for Carcinogenic Effects (days)
350 Reasonable
365 Worst-Case
9 Average
30 90th Percentile
15
350
30
70
10,950
25,550
Standard exposure factor for this pathway (EPA, 19916)
Parameter accounts for time spent away from home (EPA, 1991 a)
Upper 90th Percentile for time spent in one residence (EPA, 1 991 a)
Standard exposure factor (EPA, 1 989a)
30 years x 365 days/year = 10,950 days (EPA, 1989a)
70 years x 365 days/year = 25,550 days (EPA, 1989a)
KN/3187/WP31S7.5-7/01-22-96(9:28am)/D)/El
-------
Table 5-7
Parameters Used to Estimate Exposure
Williams Air Force Base
(Page 2 of 5)
Parameter
Range
Value Used
Rationale
Residential Exposure: Dermal Contact with Chemicals In Water
Skin Surface Area Available for Contact (cm2)
Dermal Permeability Constant (cm/hr)
Exposure Time (hours/day)
Exposure Frequency (days/year)
Exposure Duration (years)
Adult Body Weight (kg)
Averaging Time for Noncarcinogenic Effects (days)
Averaging Time for Carcinogenic Effects (days)
19,400 -50th
Percentile
(Adult Males)
16,900 -50th
Percentile
(Adult Females)
0.1 7 to 0.25
350 Reasonable
365 Worst-Case
9 Average
30 90th Percentile
18.150
Chemical-specific
values
0.25
350
30
70
10,950
25,550
The 50th percentile values for total skin surface area are cited as
default factors for adults (EPA, 1 992a). Male and female values were
averaged.
Permeability values were obtained or derived as described by EPA,
1992a (See Table 6-1, OU-3 Rl report)
EPA. 1992a
Parameter accounts for time spent away from home (EPA, 1991 a)
Upper 90th percentile for time spent in one residence (EPA, 1991 a)
Standard exposure factor (EPA, 1989a)
30 years x 365 days/year = 10,950 days (EPA, 1989a)
70 years x 365 days/year = 25,550 days (EPA, 1989a)
Residential Exposure: Incidental Ingestlon of Soil (Juvenile)
Juvenile Soil Ingestion Rate (mg/day)
Fraction Ingested from Contaminated Source
(unitless)
200
1
Standard exposure factor for children 1 through 6 years old (EPA, 19-
91 a)
Represents the fraction of the ingestion rate that is attributable to the
source. Since the residence is the source, it is assumed that 100%
of the soils/dusts are from that area (EPA, 1989a)
KN/3187/WP3187.5-7/01-22-96(9:28am)/D)/El
-------
Table 5-7
Parameters Used to Estimate Exposure
Williams Air Force Base
(Page 3 of 5)
Parameter
Exposure Frequency (days/year)
Exposure Duration (years)
Juvenile Body Weight (kg)
Averaging Time for Noncarcinogenic Effects (days)
Averaging Time for Carcinogenic Effects (days)
Range
350 Reasonable
365 Worst-Case
Age-specific
duration
Age-specific
averaging times
Value Used
350
6
15
2,1 90 (juvenile)
25,550
Rationale
Parameter accounts for time spent away from home (EPA, 1991 a)
Standard exposure factor to be used with age-specific factors
throughout the calculation (EPA, 1991 a)
Average body weight for juveniles 1 through 6 years old (EPA,
1991 a)
6 years x 365 days/year = 2,190 days for juveniles (EPA, 1989a)
70 years x 365 days/year - 25,550 days (EPA, 1989a)
Residential Exposure: Dermal Contact with Soil (Juvenile)
Exposed Surface Area (cm2/event), Juvenile
Soil-to-Skin Adherence Factors (mg/cm2)
Absorption Factor (unitless factor)
Exposure Frequency (events/year)
Exposure Duration (years)
Juvenile Body Weight (kg)
Averaging Time for Noncarcinogenic Effects (days)
Averaging Time for Carcinogenic Effects (days)
0.17-1.5
350 Reasonable
365 Worst-Case
Age-specific
duration
1700
0.2
Chemical-specific
350
6
15
2,190 (juvenile)
25,550
Assumes 15-year-old receptors expose their hands, forearms, feet,
and lower legs to soil.
Average value (EPA, 1 992)
See Table 6-1, OU-3 Rl report
Parameter accounts for time spent away from home (EPA, 1991 a)
Standard exposure factor to be used with age-specific factors
throughout the calculation (EPA, 1991 a)
Average body weight for juveniles 1 through 6 years old (EPA,
1991 a)
6 years x 365 days/year = 2,190 days for juveniles (EPA, 1989a)
70 years x 365 days/year = 25,550 days (EPA, 1 989a)
KN/3187/WP3187.5-7/01-22-96(9:28am)/D)/El
-------
Table 5-7
Parameters Used to Estimate Exposure
Williams Air Force Base
(Page 4 of 5)
Parameter
Range
Value Used
Rationale
Residential Exposure: Inhalation of Volatlles/Fugltlve Dusts (Adult)
Adult Inhalation Rate (m3/day)
Exposure Frequency (days/year)
Exposure Duration (years)
Body Weight (kg)
Averaging Time for Noncarcinogenic Effects (days)
Averaging Time for Carcinogenic Effects (days)
350 Reasonable
365 Worst-Case
9 Average
30 90th Percentile
20
350
30
70
10,950
25,550
Standard exposure factor (EPA, 1 991 a).
Parameter accounts for time spent away from home (EPA, 1991 a).
Upper 90th percentile for time spent in one residence (EPA, 1991 a).
Standard exposure factor (EPA, 1989a)
30 years x 365 days/year = 10,950 days (EPA, 1989a)
70 years x 365 days/year « 25,550 days (EPA, 1989a)
Occupational Exposure: Incidental Ingestlon of Soil
Adult Soil Ingestion Rate (mg/day)
Exposure Frequency (days/year)
Exposure Duration (years)
Body Weight (kg)
Averaging Time for Noncarcinogenic Effects (days)
Averaging Time for Carcinogenic Effects (days)
25 years = the 95th
Percentile
50
250
25
70
9125
25,550
Standard exposure factor (EPA, 1991 a)
Assumes workers are exposed 5 days/Week, 50 weeks/year (EPA,
1991 a)
95th percentile (EPA, 1991 a)
Standard exposure factor (EPA, 1989a)
25 years x 365 days/year - 9125 days (EPA, 1989a)
70 years x 365 days/year = 25,550 days (EPA, 1 989a)
Occupational Exposure: Inhalation of Volatlles/Fugltlve Dusts
Adult Inhalation Rate (m3/day)
20
Standard exposure factor of 20 m3/8-hour work day (EPA, 1991 a)
KN/3187/WP3187.5-7/01 -22-96(9:28am)/D)/El
-------
Table 5-7
Parameters Used to Estimate Exposure
Williams Air Force Base
(Page 5 of 5)
Parameter
Exposure Frequency (days/year)
Exposure Duration (years)
Body Weight (kg)
Averaging Time for Noncarcinogenic Effects (days)
Averaging Time for Carcinogenic Effects (days)
Range
25 years - the 95th
Percentile
Value Used
250
25
70
9125
25.550
Rationale
Assumes workers are exposed 5 days/week, 50 weeks/year (EPA,
1991 a)
95th percentile (EPA, 1991 a)
Standard exposure factor (EPA, 1989a)
25 years x 365 days/year - 9,125 days (EPA, 1989a)
70 years x 365 days/year « 25,550 days (EPA, 1989a)
Occupational Exposure: Dermal Contact with Soil
Exposed Surface Area (cm2/event)
Soil to Skin Adherence Factor (mg/cm2)
Absorption Factor (unitless)
Exposure Frequency (events/year)
Exposure Duration (years)
Body Weight (kg)
Averaging Time for Noncarcinogenic Effects (days)
Averaging time for Carcinogenic Effects (days)
0.17-1.5
25 years - 95th
percentile
3100
0.2
Chemical-specific
250
25
70
9125
25,550
Assumes workers expose arms and hands to soil (EPA, 1992a)
Average value (EPA, 1992a)
See Table 6-1. OU-3 Rl report
Assumes workers are exposed 5 days/Week, 50 weeks/year (EPA,
1991 a)
95th percentile (EPA, 1991 a)
Standard exposure factor (EPA, 1989a)
25 years x 365 days/year = 9125 days (EPA, 1989a)
70 years x 365 days/year = 25,550 days (EPA, 1989a)
KN/3187/WP3187.5-7/01 -22-96(9:28am)/D)/El
-------
Table 5-8
Estimated Exposure-Point Concentrations for the
Fire Protection Training Area No. 2
Williams Air Force Base
(Page 1 of 2)
Constituent
Exposure-Point Concentration
Used
Rationale for Value Used
^ DeOTalofliactandl8ge^on « G«>asdwal4r , ' ,
Orqanics (uo/L)
Acetone
Carbon disulfide
Methylene chloride
Inorqanics (uq/L)
Lead
Zinc
4.3
6.4
2.9
6.5
2500
Upper 95% confidence limit on
the arithmetic mean from
groundwater data. A value of
one-half the detection limit was
used in the statistical
calculations for undetected
data.
- Hnl^dlfOD Of vOiSfil&Si PftifJi GfOulTOWicJf&f'
'. " ^^ -wTfTin- ..
Orqanics (mq/m3)
Acetone
Carbon disulfide
Methylene chloride
0.00215
0.0032
0.00145
Calculated from the upper 95%
confidence limit on the
arithmetic mean for
groundwater data using a
home water-use volatilization
model.
* S'&sml Contact are* foddfintal Ir^siKsi - Soil
Orqanics (mq/kq)
"\ ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Acetone
Benzene
Bis(2-ethylhexyl)phthalate
Chloroform
Ethyl benzene
Methyl ethyl ketone
Methylene chloride
Toluene
Xylenes
Inorqanics (mq/kq)
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Zinc
4.03
8.23
0.017
7.32
1.39
0.66
6.64
112
3.04
9.41
27.4
4.6
16.4
20
18
7.0
18
62
Calculated from the upper 95%
confidence limit on the
arithmetic mean for soil data.
A value of one-half the
detection limit was used in the
statistical calculations for
undetected data.
KN/3187/WP3187.5-9/01-22-96(9:28am)/DO/El
-------
Table 5-8
Estimated Exposure-Point Concentrations for the
Fire Protection Training Area No. 2
Williams Air Force Base
(Page 2 of 2)
Constituent
Exposure-Point Concentration
Used
Rationale for Value Used
fr&afetiGB of Fuglive Dust
Orqanics (mo/m3)
1,2-Dichlorobenzene
1,4-Dichlorobenzene
Acetone
Benzene
Bis(2-ethylhexyl)phthalate
Chloroform
Ethyl benzene
Methyl ethyl ketone
Methylene chloride
Toluene
Xylenes
Inorganics (mq/m3)
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Zinc
4.03 x 10'7
8.23 x10'7
1.70x1(T9
7.32 x10"7
1.39X10'7
6.60 xKT8
6.64 x 10'7
1.12x 10~5
3.04 x10'7
9.41 x 10"6
2.74 X10"6
4.60 x10'7
1.64 xlO'6
2.00 x 10"6
1.80X10"6
7.00 x 10"7
1.80 X10"6
6.20 x 10"6
Calculated from the upper 95%
confidence limit on the
arithmetic mean for soil data,
using a dust loading model.
?nhaia8on of Volatiies from Sol^
Volatile Oroanics (mg/m3)
Acetone
Benzene
Chloroform
1,2-Dichlorobenzene
1,4-Dichlorobenzene
Ethyl benzene
Methyl ethyl ketone
Methylene chloride
Toluene
Xylenes
2.44 x 10'5
4.20 x ID"4
9.34 X10"4
3.32 x 10'5
8.00 x 10'5
3.18 X10"4
4.96 x 10'2
8.48 X10"3
1.69X10"3
1.85 X10"3
Calculated from upper 95%
confidence limit on the
arithmetic mean for soil data
using a subsurface soil
volatilization model.
Kl-J/3187/WP3187.5-9/01-22-96(9:28in>)/DO/El
-------
Table 5-9
Estimated Exposure-Point Concentrations for the
Southwest Drainage System
Williams Air Force Base
(Page 1 of 3)
Constituent
Exposure-Point
Concentration Used
Rationale for Value Used
; Dertrial Cootaa anrf Jnckiertal Irige^sm * Soi
Orqanics (mq/kq)
1,1,1-Trichloroethane
Acetone
Ethyl Alcohol
Methylene Chloride
Toluene
Bis(2-ethylhexy!)phthalate
Di-n-butyl phthalate
Diethyl phthalate
Phenol
Pyrene
Inorqanics (mq/kq)
Antimony
Arsenic
Beryllium
Cadmium
Chromiumd
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
0.0043
0.0833
0.036b
0.063
0.004°
3.64b
0.25b
0.25b
0.38a
0.27*
30.23
2.5a
1.2a
12.4a
33.2a
3S.323
53.4a
0.113
25.8a
0.68a
2.5a
2.8b
152.53
Upper 95% confidence limit on the
arithmetic mean for soil data. A value
of one-half the CRDL was used in the
statistical calculations for undetected
data.
KN/3187/WP3187.5-9A>l-22-96(9:30am)/DO/El
-------
Table 5-9
Estimated Exposure-Point Concentrations for the
Southwest Drainage System
Williams Air Force Base
(Page 2 of 3)
Constituent
Exposure-Point
Concentration Used
Rationale for Value Used
iflNiJatloj* Of i^gifw* £usl
Oraanics (mo/m3)
1,1,1-Trichloroethane
Acetone
Ethyl Alcohol
Methylene Chloride
Toluene
Bis(2-ethylhexyl)phthalate
Di-n-butyl phthalate
Diethyl phthalate
Phenol
Pyrene
Inoraanics (mo/m3)
Antimony
Arsenic
Beryllium
Cadmium
Chromium*1
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
4.0 x10"10
8.3 x10~9
3.6 x10'9
6.0 x10'9
4.0 x 10'10
3.6 x10'7
2.5 X10"8
2.5 X10"8
3.8 X10"8
2.7X1Q-8
3.0 X10"6
2.5 x 10'7
1.2x10'7
1.2X10"6
3.3x10"*
3.3 x 10"6
5.3 X10"6
1.1 X10"8
2.6 x 10"6
6.8 X10"8
2.5 X10'7
2.8 x10'7
1.5 X10"5
Calculated from the upper 95%
confidence limit on the arithmetic mean
interval for soil data using a dust
loading factor of 6 x 10"4 g/m3.
KN/3187/WP3187.5-9A>l-22-9«(9:30«in)/DO/El
-------
Table 5-9
Estimated Exposure-Point Concentrations for the
Southwest Drainage System
Williams Air Force Base
(Page 3 of 3)
Constituent
Exposure-Point
Concentration Used
Rationale for Value Used
: lt*^HonofVolaSles^mSoli
Volatile Orqanics (mo/m3)
1 ,1 ,1 -Trichloroethane
Acetone
Ethyl Alcohol
Methylene Chloride
Toluene
0.00073
0.029
0.027
0.024
0.00022
Calculated from the upper 95%
confidence limit on the arithmetic mean
for soil data (samples from 0 to 1 foot)
using a surface soil volatilization
model.
aValue for surface soil data summary.
bValue from combination surface and subsurface soil data summary.
cValue from subsurface soil data summary.
dUpdated values, differing from values reported in Chapter 6 of OU-3 Rl.
KN/3187/WP3187.5-9A>l-22-96(9:30am)/DO/El
-------
SD-09 has no groundwater sample data; therefore no exposure-point concentrations are
calculated. Also, it was concluded that it would not be appropriate to use groundwater
contaminant fate and transport models as a means for obtaining exposure-point concentrations
for future land-use conditions (Section 6.3.3, OU-3 RI report). The primary reasons for
excluding modeling were due to the arid conditions in Arizona, resulting in negligible
precipitation driven chemical infiltration to the groundwater, and a detected decrease of COPC
concentrations in the soil borings with increasing depths.
For the groundwater sample data at FT-02, the upper 95th percent confidence limit of the
arithmetic mean of the current monitoring data was used as the future RME concentration. It
was expected that future concentrations in groundwater would be less than those represented
by the current exposure-point concentrations due to degradation and/or dilution during
transport. The use of current data for the RME excludes both the potential for increased
concentrations in the near future and decreased concentrations in the more distant future.
This assumption of steady-state conditions should result in a health-protective estimate
because exposure is not anticipated in the near future.
Indoor Air. The upper 95th percent confidence limit of the arithmetic mean of the ground-
water monitoring data was used to estimate the potential concentration of VOCs during home
o
use of groundwater. The concentrations of VOCs in air (milligrams per cubic meter [mg/m ])
are estimated by multiplying their concentrations in water (|J.g/L) by the volatilization factor
of 0.0005 L-mg/n.g-m3. Results are presented in Table 5-8.
So/7. FT-02 soil samples were analyzed from depths of 1 to 210 feet bgs. Because useable
samples were taken from the surface (0 to 1 foot), soil data from the first 25 feet bgs were
used in the risk assessment. Analytical results from the three surface soils samples, primarily
to define the extent of surface soil contamination with PAHs, were included. The data did
not indicate that the FT-02 surface soils were contaminated with PAHs.
SD-09 soil samples were analyzed from depths of 0 to 40.5 feet bgs. It was decided, due to
the nature of the site and chemicals detected, to include data only to 25 feet bgs. Data from
surface and subsurface soils were combined and, in most cases, the higher concentration
(more conservative) value was chosen as the exposure point concentration.
RME concentrations were estimated as the upper 95th percent confidence limit of the
arithmetic mean of the sampling data for each COPCs in each group. (For samples with no
KN/3187/WP3187.5/01-22-96(9:23am)/DO/El 5-8
-------
detectable concentration of a chemical, a value of one-half the CRDL was used.) RME will
tend to overestimate exposure to surface soils, especially in the future, because concentrations
are expected to decrease with time through weathering and volatilization.
Volatilization from Soils. Receptors in the site areas could potentially be exposed to
vapor-phase chemicals due to volatilization of organic compounds present in the surface or
subsurface soils. Volatilization and dispersion models were used to estimate air concentra-
tions of VOCs based on their concentrations in soil. First, a VOC flux from soil was
calculated, then air dispersion was modeled for on-site receptors. Model assumptions and
parameters are presented in great detail in Section 6.3.3 of the OU-3 RI report. The upper
95th percent confidence limit of the arithmetic mean of the soil data was used to estimate the
potential concentration of chemicals in the air because of volatilization.
Air Dispersion Model. Dispersion of volatiles into air was estimated using the Near Field
Box Model, which calculates the ambient air concentration based on the assumption that the
volatiles are uniformly distributed in a hypothetical box, of finite height, downwind from the
site.
Fugitive Dust. Estimating airborne concentrations of chemicals in the particulate phase
involves modeling resuspension and dispersion. Resuspension of hazardous chemicals were
estimated using a simple dust loading equation (DOE, 1989). This method is useful for
estimating exposure concentrations of chemicals in air for construction workers or those
involved in remediation activities at the contaminant release point.
5.3.4 Uncertainties
There are several sources of uncertainty in the exposure assessment process that may ult-
imately impact the risk assessment. These sources can be generally categorized as: current
and future land-use assumptions, media sampling and analysis, evaluation of exposure
pathways, and exposure parameter values.
5.4 Toxicity Assessment
5.4.1 Contaminant Toxicity
The toxicity assessment provides information regarding the type and severity of adverse
health effects that could result from exposure to COPCs and a measure of the dose-response
relationship for each chemical. These dose-response relationships for oral, inhalation, and
KN/3187/WP3187.5A>l-22-96<9:23ain)/DO/El 5-9
-------
dermal toxicity are expressed quantitatively as reference doses (RfD) and slope factors (SF),
which have been derived by the EPA. The sources of these values are the Integrated Risk
Information System (IRIS) (EPA, 1994a) and the Health Effects Assessment Summary Tables
(HEAST) (EPA, 1993), unless otherwise stated. This information is summarized in Tables 5-
10 and 5-11.
Slope factors, derived by the EPA, expressed in units of (mg/kg-day)"1, are multiplied by the
estimated intake of a potential carcinogen, in units of mg/kg-day, to provide an upper bound
estimate of excess lifetime cancer risks associated with exposure at that intake level. The
term "upper-bound" reflects the conservative estimate of risks calculated from the SF.
RfDs have been developed by the EPA for indicating the potential for adverse health effects
from exposure to chemicals exhibiting noncarcinogenic effects. RfDs, expressed in units of
mg/kg-day, are estimates of an average lifetime exposure levels for humans, including
sensitive individuals, not expected to result in adverse effects. Estimated intakes of chemicals
are compared to RfDs because exposure to a chemical above this average intake level is a
potential cause for an adverse health effect.
5.4.2 Dermal Toxicity Values
Dermal RfD values and SFs (Table 5-12) are derived from the corresponding oral values,
provided there is no evidence to suggest that dermal exposure induces exposure route-specific
effects that are not appropriately modeled by oral exposure data. In the derivation of a
dermal RfD, the oral RfD is multiplied by the gastrointestinal absorption factor (GAP),
expressed as a decimal fraction. The resulting dermal RfD, therefore, is based on absorbed
dose. The RfD based on absorbed dose is the appropriate value with which to compare a
dermal dose, because dermal doses are expressed as absorbed rather than exposure or contact
doses. The dermal SF is derived by dividing the oral SF by the GAF. The oral SF is divided,
rather than multiplied, by the GAF because SFs are expressed as reciprocal dose.
5.5 Risk Characterization
This section provides a characterization of the potential health risks associated with the intake
of chemicals at OU-3. The methods for estimating risk from carcinogenic and noncarcino-
genic COPCs are presented in this section, followed by a qualitative discussion of risks from
COCs with no available toxicity data. The results of the risk assessment are presented for
FT-02 and SD-09, followed by a discussion of uncertainties in risk characterization.
KN/3187/WP31875/01-22-96(923am)/DO/El 5-10
-------
Table 5-10
Summary of Slope Factors
Williams Air Force Base
(Page 1 of 2)
Constituent
Acetone
Antimony
Arsenic
Benzene
Beryllium
Bis(2-ethylhexyl)phthalate
Cadmium
Carbon disulfide
Chloroform
Chromium
Copper
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Diethyl phthalate
Di-n-butyl phthalate
Ethyl alcohol
Ethyl benzene
Lead
Oral Slope Factor
(SF)
(mg/kg-day)"1
NA
NE
1.8
2.90 x 10'2
4.30
1.40X10'2
NL
NE
6.10 x 10"3
NL
NA
NA
2.40 x 10'2b
NA
NA
NE
NA
NL
Weight of
Evidence
D
NE
A
A
B2
B2
NL
NE
B2
NL
D
D
C
D
D
NE
D
B2
Type of Cancer
NA
NE
Skin
Leukemia
Total tumors
Liver
NL
NE
Kidney
NL
NA
NA
Liver
NA
NA
NE
NA
NL
Inhalation Slope
Factor (SF)
(mg/kg-day)"1
NA
NE
15a
2.90 x 10'2b
8.40b
NL
6.30a
NE
8.10 x 10'2b
4.10x101b
NA
NA
NL
NA
NA
NE
NA
NL
Weight of
Evidence
D
NE
A
A
B2
B2
B1
NE
B2
A
D
D
C
D
D
NE
D
B2
Type of Cancer
NA
NE
Lung
Leukemia
Lung
NL
Respiratory tract
NE
Liver
Lung
NA
NA
NL
NA
NA
NE
NA
NL
KN/3l87/WP3187,510/01-22-96(9:30am)/DO/El
-------
L.
Table 5-10
Summary of Slope Factors
Williams Air Force Base
(Page 2 of 2)
Constituent
Mercury
Methyl ethyl ketone
Methylene chloride
Nickel
Phenol
Pyrene
Selenium
Silver
Thallium compounds
Toluene
1,1,1-Trichloroethane
Xylenes
Zinc
Oral Slope Factor
(SF)
(mg/kg-day)"1
NA
NA
7.50 x 10"3
NL
NA
NA
NA
NA
NA
NA
NA
NA
NA
Weight of
Evidence
D
D
B2
NL
D
D
D
D
D
D
D
D
D
Type of Cancer
NA
NA
Liver
NL
NA
NA
NA
NA
NA
NA
NA
NA
NA
Inhalation Slope
Factor (SF)
(mg/kg-day)"1
NA
NA
1.65x 10"33
8.4 x 10"1b
NA
NA
NA
NA
NA
NA
NA
NA
NA
Weight of
Evidence
D
D
B2
A
D
D
D
D
D
D
D
D
D
Type of Cancer
NA
NA
Lung, liver
Respiratory tract
NA
NA
NA
NA
NA
NA
NA
NA
NA
aValue converted from unit risk estimate to slope factor using conversion method in Health Effects Assessment Summary Tables (HEAST) (EPA, 1993).
bValues obtained from HEAST.
NA - Not applicable.
NE - Chemical has not been evaluated for carcinogenicity.
NL - Not listed.
The source of the toxicity values is the Integrated Risk Information System (IRIS) (EPA, 1994a) unless otherwise indicated in the footnotes.
KN/3187/WP3187.510/01-22-96(9:30am)/DO/El
-------
Table 5-11
Summary of Reference Doses
Williams Air Force Base
(Page 1 of 3)
Constituent
Acetone
Antimony
Arsenic
Benzene
Beryllium
Bis(2-ethylhexyl)phthalate
Cadmium
Cadmium
Carbon disulfide
Chloroform
Chromium VI
Copper
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Diethyl phthalate
Oral Reference
Dose (RfD)
(mg/kg-day)
I.OOxKT1
4.00 x 10"4
3.00 x 10"4
NL
5.00 x 10'33
2.00 x10'2
5.00 x 10"4 (water)
LOOxlO^ffood)
1.00X10'1
1.00X10'2
5.00 x 1Q-3
NLd
9.00 x 10'2
NL
8.00 x 10'1
Target Organ
Kidney
Cardiovascular
system
Skin
NL
ND
Liver
Kidney
Kidney
Fetus
Liver
ND
Local
gastrointestinal
irritation
Liver
NL
ND
Uncertainty Factor
1000
1000
3
NL
100
1000
10
10
100
1000
500
NL
1000
NL
1000
Inhalation Reference
Dose (RfD)
(mg/kg-day)
NL
NL
NL
NL
NL
NL
NL
NL
2.90 x 10'3b>c
NL
NL
NL
4.00 x 10'2b
2.39 x 10"1b'c
NL
Target Organ
NL
NL
NL
NL
NL
NL
NL
NL
Fetus
NL
NL
NL
ND
Liver
NL
Uncertainty
Factor
NL
NL
NL
NL
NL
NL
NL
NL
1000
NL
NL
NL
1000
100
NL
KN/3187/WP3187.511/01-22-96(9:31am)/DO/El
-------
Table 5-11
Summary of Reference Doses
Williams Air Force Base
(Page 2 of 3)
Constituent
Di-n-butyl phthalate
Ethyl alcohol
Ethyl benzene
Lead
Mercury
Methyl ethyl ketone
Methylene chloride
Nickel
Phenol
Pyrene
Selenium
Silver
Thallium
Toluene
1,1,1-Trichloroethane
Oral Reference
Dose (RfD)
(mg/kg-day)
1.00X10'1
NL
1.00X10"1
NL
3.00 x 1Q~4b
6.00 X10'1
6.00 x 10'2
2.00 x 10'2b
6.00 x 10"1
3.00 x 10'2
5.00 x 10'3
5.00 x 10'3
6 x 10'56
2.00 x10'1
9.0 x 10'2f
Target Organ
ND
NL
Liver
NL
Kidney
Fetus
Liver
ND
Fetus
Kidney
Skin
Skin
Skin
Liver
Liver
Uncertainty Factor
1000
NL
1000
NL
1000
3000
100
300
100
3000
3
3
3000
1000
1000
Inhalation Reference
Dose (RfD)
(mg/kg-day)
NL
NL
2.86x10'1c
NL
8.6x10'5b>c
2.9 x 10"1
8.60 x 10'1c
NL
NL
NL
NL
NL
NL
1.10x10'1c
3.0 x 10"1f
Target Organ
NL
NL
Fetus
NL
Nervous system
Fetus
Liver
NL
NL
NL
NL
NL
NL
Nervous system
Liver
Uncertainty
Factor
NL
NL
300
NL
30
3000
100
NL
NL
NL
NL
NL
NL
30
1000
KN/3187/WP3187.511/01-22-96(9:3Um)/DO/El
-------
Table 5-11
Summary of Reference Doses
Williams Air Force Base
(Page 3 of 3)
Constituent
Xylenes
Zinc
Oral Reference
Dose (RfD)
(mg/kg-day)
2.00
3.00 x 10'1
Target Organ
Nervous system
Blood
Uncertainty Factor
100
3
Inhalation Reference
Dose (RfD)
(mg/kg-day)
NL
NL
Target Organ
NL
NL
Uncertainty
Factor
NL
NL
ND - Not determined.
NL - Not listed.
UF - Uncertainty factor.
The source of the toxicity values is the Integrated Risk Information System (IRIS) (EPA, 1994b) unless otherwise indicated in the footnotes.
aValue based upon soluble salts of beryllium.
bValue obtained from the Health Effects Assessment Summary Tables (HEAST) (EPA, 1993).
°Value converted from reference concentration (RfC) to inhalation RfD according to method in HEAST.
dAn RfD was not estimated from the drinking water standard for copper of 1.3 mg/L because the drinking water standard is based on acute effects and an RfD
derived therefrom may not be protective for chronic effects.
eDerived by analogy to thallium sulfate by adjusting for differences in molecular weight.
fTaken from 1992 HEAST (U.S. EPA, 1992b).
KN/3187/WP3187.511/01-22-96(9:31»m)/DO/El
-------
Table 5-12
Summary of Dermal Reference Doses
and Dermal Cancer Slope Factors
Williams Air Force Base
(Page 1 of 2)
Constituent
Acetone
Antimony
Arsenic
Benzene
Beryllium
Bis(2-ethylhexyl)phthalate
Cadmium
Carbon Disulfide
Chloroform
Chromium
Copper
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Diethyl phthalate
Di-n-butyl phthalate
Ethyl alcohol
Ethyl benzene
Lead
Mercury
Methyl ethyl ketone
Methylene chloride
Nickel
Phenol
Pyrene
GAFa
0.83d
0.058
0.95d
1.0f
0.01d
0.9g
0.05d
0.99
1.0f
0.05f
0.&
0.99
0.99
0.99
0.85f
0.9s
0.9f
0.1f
0.15d
0.95d
1.0f
0.1d
0.9g
0.99
Dermal Reference
Dose (RfD)
(mg/kg-day)b
8.3 x10'2
2.0 X10"5
2.9 X10"4
ND
5.0 X10'5
1.8 x10'2
2.5 x10'5
9.0 x 10'2
1.0X10'2
2.5 X10"4
ND
8.1 x 10'2
ND
7.2 x10'1
8.5 x10'2
ND
9.0 x10'2
ND
4.5 X10"5
5.7 x 10"1
6.0 x10'2
2.0 X10"3
5.4 x 10'1
2.7 x 10'2
Dermal Slope
Factor (SF)
(mg/kg-day)'1c
ND
ND
1.9
2.9 x 10'2
430
1.6 x10'2
ND
ND
6.1 x 10"3
ND
ND
ND
2.7 X10'2
ND
ND
ND
ND
ND
ND
ND
7.5 xlO"3
ND
ND
ND
KN/3187/WP31S7512A)l-22-96(9:32ain)/DO/El
-------
Table 5-12
Summary of Dermal Reference Doses
and Dermal Cancer Slope Factors
Williams Air Force Base
(Page 2 of 2)
Constituent
Selenium
Silver
Thallium
Toluene
1,1,1 -Trichloroethane
Xylenes
Zinc
GAFa
0.6f
NAh
0.059
1.0d
0.9g
0.9d
0.25d
Dermal Reference
Dose (RfD)
(mg/kg-day)b
3.0 xlO"3
ND
3X10"6
2.0 x10'1
8.1 x 10'*
1.8x10°
7.5 x10'2
Dermal Slope
Factor (SF)
(mg/kg-day)"1c
ND
ND
ND
ND
ND
ND
ND
aGAF = Gastrointestinal absorption factor.
bDermal RfD is derived by multiplying the oral RfD by the GAF (Section 5.4.2).
cDermal SF is derived by dividing the oral SF by the GAF (Section 5.4.2).
dEPA, 1993b.
eDefault value: metals tend to be poorly absorbed by the gastrointestinal tract (EPA, 1989a).
fJones and Owen, 1989.
9Default (Section 6.4.3, OU-3 Rl report).
hDermal contact with silver induces local skin discoloration, and oral exposure to silver induces silver
accumulation in internal organs; therefore, oral exposure is not an acceptable model for dermal exposure,
and dermal toxicity values are not derived from oral toxicity values.
ND = Not derived.
NA = Not applicable.
KN/3187/WP31S7.512/01-22-96(9:32ajnVDO/El
-------
5.5.1 Carcinogens
ILCR were estimated for each chemical. ILCR is expressed in terms of additional cancers
that might be anticipated as a result of specific exposure to an external influence. Thus, a
10~6 ILCR indicates that one additional person in one million is likely to develop some form
of cancer or that an exposed individual has an additional one-in-one-million chance of
developing cancer. ILCR is estimated by multiplying a chemical's SF, in (mg/kg-day)'1, by
its intake value, in mg/kg-day (EPA, 1989a).
In evaluating acceptable residential exposures to potentially carcinogenic compounds, the EPA
recommends the use of an acceptable risk range of 10"4 to 10"6 for CERCLA sites (EPA,
1990a). EPA also uses an incremental lifetime risk level of one in one million as the bottom
of the acceptable range for developing drinking water standards (EPA, 1987). The maximum
acceptable ILCR recommended by the EPA for drinking water is 10"4 (EPA, 1987).
5.5.2 Noncarcinogens
Chemicals that produce health effects other than cancer were evaluated in terms of their
relative hazard when compared to acceptable exposure levels. The hazard quotient (HQ),
used to quantify noncancer health hazards, for exposure to noncarcinogens is the ratio of the
estimated daily intake to the RfD for that chemical (EPA, 1989a). The HQ does not address
intake-response relationships and its numerical value should not be construed to be a
probabilistic estimate of risk. It is a numerical proximity to acceptable limits of exposure or
the degree to which acceptable exposure levels are exceeded. If this index exceeds unity,
concern for the potential hazard of the chemical increases. Exceeding unity does not in itself
imply a potential hazard; however, it does suggest that a given situation should be more
closely scrutinized.
The sum of all hazard quotients for a given pathway or medium is the hazard index (HI).
EPA (1989a) advocates the use of total HI for a mixture of components based on the
assumption of response additivity. Summation of the individual HQs could result in an HI
that exceeds 1, even if no single chemical exceeds its acceptable level. Mechanistically, it is
not appropriate to sum HQs unless the chemicals that compose the mixture have similar
modes of action on the identical organ. Consequently, the summing of HQs for a mixture of
compounds that are not expected to induce the same type of effects could overestimate the
potential risk. The EPA recommends that if the total HI is greater than unity, the components
of the mixture should be grouped by critical effect (target organ) and separate His should be
KN/3187/WP3187.5A>l-22-96<9:23amyDO/El 5-11
-------
derived for each effect. Critical effects are described in the HEAST and in IRIS (EPA, 1993,
1994a) and are summarized in Table 5-11.
5.5.3 Chemicals with No Published Toxicity Values
Copper. EPA (1993) notes that the current drinking water standard for copper is 1.3 mg/L.
The data, however, based on gastroenteritis arising from acute exposure, are not sufficient for
derivation of an oral RfD. Copper was not detected in FT-02 groundwater. The 95 percent
upper confidence level on the mean concentrations in FT-02 soils (20 mg/kg), SD-09 surface
soils (50 mg/kg) and SD-09 subsurface soils (19 mg/kg), although above the Base-specific
background concentration (<5 mg/kg), were within or below the regional background
concentration range (30 to 50 mg/kg), and were also below the EPA Region DC PRO for
residential soil of 2900 mg/kg (EPA, 1994b), and are not expected to induce adverse effects.
Ethyl Alcohol. In the absence of toxicity values, the potential toxicity of ethyl alcohol was
evaluated qualitatively. Ethyl alcohol was detected in one out of 31 surface soil samples and
in five of 32 subsurface soil samples from SD-09. The 95 percent upper confidence level on
the mean concentration was 0.033 mg/kg in surface soil and 0.042 mg/kg in subsurface soil.
The exposure pathways that were investigated for SD-09 include: incidental ingestion of
soils, dermal contact with soil, inhalation of volatiles from soils, and inhalation of fugitive
dusts. Given the frequency of samples in which alcohol was detected and the relatively low
soil concentrations, the effects of ethyl alcohol associated with the SD-09 surface soils are
expected to be negligible.
Lead. There are no oral RfD or inhalation RfC/RfD values for lead, primarily because
effects may occur at doses so low as to appear to be without thresholds, and because lead is
ubiquitous in all environmental media so that the contribution to total body intake from one
exposure pathway (e.g., ingestion of contaminated soil) cannot be quantified (EPA, 1990b;
1994b).
Version 99D of the Integrated Exposure Uptake Biokinetic Model for Lead in Children
(IEUBK) (EPA, 1994c) was used to evaluate lead in drinking water and soil for FT-02, and
lead in soil for SD-09, although the latest EPA guidance (1994d) does not recommend further
evaluation if soil lead levels are below 400 mg/kg. The IEUBK integrates lead uptake from
inhalation, drinking water, diet, soil and dust ingestion, and ingestion of incidental sources
KN/3187/WP3187J/01-22-96(923iin)/DO/El 5-12
-------
such as chips of lead-based paint, and estimates blood lead concentrations over the first 7
years of a child's life. The BEUBK was run for FT-02 groundwater and SD-09 soils.
In all cases, modeled blood lead concentrations were less than or equal to 10 micrograms per
deciliter (p.g/dL) for 95 percent of hypothetically exposed children (i.e., that blood lead
concentrations exceeded 10 fig/dL for less than 5 percent of hypothetically exposed children,
which conforms to the latest [EPA, 1994d] guidance on lead in soil).
Characterization of health hazards due to lead is discussed in greater detail in section 6.5.3 of
the OU-1 RI.
5.5.4 Results of Risk Characterization
When the FT-02 risk assessment was first performed and published as part of the OU-1 RI
report, the Base was operating. Since then, the Base-specific background range for inorganics
has been established and the Base has closed. This report presents the addition of five
inorganic chemicals (chromium, copper, lead, nickel, and zinc) to the original list of COCs in
soil because of the Base-specific background results. The SD-09 risk assessment, however,
represents a more complete update incorporating additional soil analytical data. In addition,
all default exposure parameter values and toxicity values used in the original risk assessment
were evaluated and updated in this version. Also, the newer (EPA, 1992) dermal exposure
assessment guidance was used to quantify uptake of chemicals from dermal exposure to
water, and the EPA (1991b) model for inhalation of volatiles from household water was used.
Risk results are summarized in Tables 5-13 and 5-14 and are computed to three significant
figures. In the text, however, risk results are expressed as two significant figures to more
realistically reflect the uncertainty inherent in risk calculations.
Fire Protection Training Area No. 2. Risk characterization results for FT-02 are
summarized in Table 5-13.
The current occupational scenario was evaluated for exposure to soil by the pathways
presented in Table 5-13. No pathway had an HI exceeding 1, or an ILCR exceeding the
target range of 10"6 to 10"4. The total receptor HI, 5.7 x 10"2, was well below 1. The total
receptor ILCR, 2.0 x 10"5, was within the target range of 10"6 to 10"4.
KN/3187/WP3187.5/01-22-96(9:23am)/DO/El 5-13
-------
Table 5-13
Summary of Risk Characterization Results
Fire Protection Training Area No. 2
Williams Air Force Base
Exposure Pathway
Total Hazard Index
Primary Contributor(s)
Total ILCR
Primary Contributor(s)
Current Occupational Scenario - Soil
Ingestion of Soil
Dermal Contact with Soil
Inhalation of Volatiles from Soil
Inhalation of Fugitive Dust from Soil
1.61 x 10'*
4.51 x 1Q-4
3.89 x ID'2
1.61 x 10"3
Mercury, Cadmium, Chromium
Ethyl benzene, Chloroform
Methy ethyl ketone
Mercury
7.97 x 10"8
1.62x 10'7
1.48X 10'5
5.01 x 10"6
Benzene
1 ,4-Dichlorobenzene
Benzene chloroform
Chromium
Total Occupational HI or ILCR: 5.70 x 10~2 2.01 x 10'5
Future Residential Scenario - Groundwater
Ingestion of Groundwater
Dermal Contact with Groundwater
Inhalation of Volatiles from Groundwater
2.33 x 10'1
3.50 X10"4
2.27 X10'1
Zinc
Carbon disutfide
Carbon disutfide
2.55 x 10'7
7.76 x 10'9
2.11 x10'7
Methylene chloride
Methylene chloride
Methylene chloride
Total Groundwater HI or ILCR: 4.60 x 10~1 4.74 x 10"7
Future Residential Scenario - Soil
Ingestion of Soil
Dermal Contact with Soil
Inhalation of Volatiles from Soil
Inhalation of Fugitive Dust from Soil
4.20 X10'1
1.62 x 10"3
5.44 X10'2
2.25 x 10"3
Mercury
Ethyl benzene
Methyl ethyl ketone
Mercury
5.00 X10'7
1.40X1Q-7
2.48 x 10"5
8.42 x 10"6
Benzene
1 ,4-Dichlorobenzene
Benzene
Chromium
Total Soil HI or ILCR: 4.80 x 10'1 3.40 x 10'5
Total Residential HI or ILCR: 9.40 x10"1 3.40 x10'5
KN/3187/WP3187.513/01-22-96(9:32am)/DO/El
-------
Table 5-14
Summary of Risk Characterization Results
Southwest Drainage System
Williams Air Force Base
Exposure Pathway
Total Hazard Index
Primary Contributor(s)
Total ILCR
Primary Contributor(s)
Current Occupational Scenario - Soil
Ingestion of Soil
Dermal Contact with Soil
Inhalation of Volatiles from Soil
Inhalation of Fugitive Dust from Soil
7.48 x10'2
3.53 x10'5
6.33 X10"3
2.50 x10"5
Antimony, Thallium
Pyrene
Methylene chloride
Mercury
1.70X10"6
7.97 x10'10
2.77 X10"6
1.05x10'5
Beryllium, Arsenic
Bis(2-ethylhexyl)phthalate,
Methylene chloride
Methylene chloride
Chromium
Total Occupational HI or ILCR: 8.12 x 10'2 1 .50 x 10'5
Current and Future Residential Scenario - Soil
Ingestion of Soil
Dermal Contact with Soil
Inhalation of Volatiles from Soil
Inhalation of Fugitive Dust from Soil
1.95X10403
1.26 X10"4
8.86 X10"3
3.50 x10'5
Antimony, Thallium, Chromium,
Cadmium, Arsenic
Pyrene
Methylene chloride
Mercury
1.06X10"5
6.86 x 10'10
4.65 x 1Q-6
1.76x10"5
Beryllium, Arsenic
Bis(2-ethylhexyl)phthalate,
Methylene chloride
Methylene chloride
Chromium
Total Residential HI or ILCR: 1.96 x 10+0a 3.29 x 10"5
aThis HI, although it exceeds 1.0, does not represent unacceptable intakes, as explained in Section 5.5.4.
KN/3187/WP3187.514/01-22-96(9:33am)/DO/El
-------
The future residential scenario was evaluated for exposure to groundwater and soil by the
pathways presented in Table 5-13. No pathway had an HI exceeding 1, or an ILCR
exceeding the target range of 10"6 to 10"4. The total ILCR for the future residential scenario,
3.4 x 10~5, was within the target range of 10"6 to 10"4. The total HI for this receptor was 9.4
x 10'1.
Southwest Drainage System. Risk characterization results for SD-09 are summarized in
Table 5-14. HI and ILCR values in Table 5-14 were computed to reflect the most recent
chromium data, as was noted in Section 5.2.2.2, and, therefore differ marginally from results
presented in the OU-3 RI report.
r\
For the current occupational scenario, the total receptor HI was 8.1 x 10 , suggesting that
there is little concern regarding adverse noncancer effects. The total ILCR is 1.5 x 10 ,
within the target risk range of 10"6 to 10"4.
For the current and future residential scenarios, the total receptor HI was 1.9, due primarily to
antimony (50 percent of total receptor HI). The only significant pathway of concern was
incidental soil ingestion by the resident child. Base subsurface soil sampling results after
1989 have not shown high concentrations of antimony (Chapter 4.0, OU-3 RI report), and it
was concluded that the unusually high source-term concentration of antimony used in this
evaluation was due to laboratory error. The remainder of the HI for incidental ingestion of
soil is due primarily to arsenic, cadmium, chromium, and thallium.
The evaluation of incidental ingestion of soil for SD-09 can be limited to arsenic, cadmium,
chromium, and thallium because together these metals contribute 97 percent of the remaining
HI (i.e., the total HI minus that due to antimony). The skin is the target organ for arsenic and
thallium; therefore, the HI for the skin is the sum of the HI values for arsenic and thallium.
The target organ for chromium has not been determined. The target organ for cadmium is the
kidney. None of the target organ HI values exceed 1, suggesting that the total HI for the
current and future residential receptor in Table 5-14 was overly conservative.
The total ILCR for the current and future residential scenario for SD-09 was 3.3 x 10"5,
within the target risk range of 10"6 to 10"4.
KN/3187/WP3187.5/01-22-96(9:23am)/DO/El 5-14
-------
5.5.5 Vegetable Ingestion Pathway
Terrestrial uptake of contaminants into vegetables is dependent on the mobility and persis-
tence of contaminants and the type of vegetation. Any contaminant with a significant
biotransfer factor could pose a greater risk through the terrestrial food chain pathway than
through the direct soil ingestion pathway, primarily because the ingestion rate of homegrown
vegetables is roughly 500 to 1,000 times higher than the rate of incidental soil ingestion.
Exposure through the food chain would also be higher than exposures through dermal contact
with soil and through inhalation of fugitive dust, primarily because the contaminant intake is
significantly less through these pathways.
Homegrown fruit and vegetable ingestion may significantly increase the risk from exposure to
mercury for the future resident exposed to FT-02. Analysis for SD-09 raises concern
regarding the uptake of arsenic and cadmium by homegrown fruits and vegetables. The
following table by Sauerback (1988) provides a qualitative guide for assessing heavy metal
uptake into a number of plants (EPA, 1991a).
Plant Uptake of Heavy Metals
High
Lettuce
Spinach
Carrot
Endive
Cress
Beet and beet leaves
Moderate
Onion
Mustard
Potato
Radish
Low
Corn
Cauliflower
Asparagus
Celery
Berries
Very Low
Beans
Peas
Melon
Tomatoes
Fruit
5.5.6 Uncertainties
A risk assessment of a site is ultimately an integrated evaluation of historical, chemical,
analytical, environmental, demographic, and lexicological data that are as site-specific as
possible. Uncertainty plays a major role in the final results of a risk assessment and exists at
every stage of the risk assessment Following is a list of some of the primary sources of
uncertainty in a risk assessment
Source-term concentrations, due to variations in the sample analytical results
Input values for exposure assessment models
KN/3187/WP31 S7.5A>l-22-96<9:23am)/DO/El
5-15
-------
Accuracy with which the models themselves represent environmental processes
High-to-low dose and interspecies extrapolations for dose response relationships.
It is not possible to eliminate all uncertainty; thus, to minimize the possibility of underesti-
mating risk, each step is biased toward health-protective estimations. For example, using the
95 percent upper confidence limit of the average contaminant concentrations in the risk
calculations is done purposely so that risk will be over- rather than underestimated. The 95
percent upper confidence limit on the mean concentration was used even when it exceeded
the maximum detected concentration. Newer EPA guidance indicates that the maximum
detected concentration could have been used in these cases, because little confidence can be
placed in an upper confidence limit that exceeds the maximum detected concentration.
Similarly, the RME scenario uses upper-bound values for environmental medium contact rates
(e.g., soil ingestion, air inhalation, and dermal contact rates), exposure frequency and
exposure duration, ensuring risk estimates that are biased toward conservatism.
The toxicity values are also biased toward conservatism. Worst-case assumptions are used
regarding human sensitivity and the adversity of observed effects in the derivation of RfDs
for noncancer effects. The SFs for cancer reflect an upper limit on the dose-effect relation-
ship, resulting in an upper-bound estimate on risk.
Additional conservatism accompanies the nature of contamination observed at each of the
individual sites. The cancer risk at FT-02, for example, is "driven" largely by a few VOCs
and chromium. However, the VOC concentrations will decrease with time due to volatili-
zation and biodegradation, so that cancer risk will also decrease with time. The chromium
risk was calculated assuming that all the chromium was present in the hexavalent (carci-
nogenic) state, although it is well established that hexavalent chromium in the environment
tends to be reduced to the trivalent (noncarcinogenic) state.
SD-09 cancer risks are driven by arsenic, beryllium, chromium, and methylene chloride. As
previously discussed, chromium was assumed to be present entirely in the hexavalent state,
although this is very unlikely and exaggerates the estimated risk. Also, concentrations of
methylene chloride will decrease with time due to volatilization and biodegradation.
Although arsenic and beryllium are major contributors to total cancer risk, their upper
confidence limits are within the range of Base-specific background, i.e., the cancer risk from
KN/31S7/WP3187.5/01-22-96{9:23ain)/DO/El 5-16
-------
exposure to these naturally-occurring metals at some uncontaminated off-site location would
be similar to the risks from exposure to SD-09.
Because each step builds on the previous one, this biased approach mathematically com-
pounds, and should more than compensate for, risk assessment uncertainties. In addition,
these calculations do not represent currently existing or expected future exposure or health
risks. Rather, they are estimates of potential risk only if all of the conservative exposure
assumptions are realized.
This qualitative discussion of uncertainty is not intended to discredit the calculated results, but
to point out that risks are calculated for a hypothetical scenario under well defined con-
straints. Recognition of uncertainties is fundamental to the proper use of these results in
guiding remedial action decision making.
5.6 Ecological Assessment
At FT-02, adverse effects are highly unlikely due to a lack of ecological receptors. Direct
mechanical stress has eliminated all habitats and community structure, leading to a lack of
ecological receptors at this study site. Small mammal or terrestrial arthropod species could
come into contact with contaminated FT-02 soils as they transit the area, but frequency of
exposure under these circumstances is presumed to be low. There is no suitable habitat at
FT-02 to encourage actual occupation of the study site by these species.
At SD-09, periodic, ongoing maintenance mowing holds the channel alignment and lagoon
basin in a permanent state of arrested secondary succession. Invertebrate and mammalian
receptors extant in communities that have formed despite these chronic disruptions could have
experienced, or could be experiencing, acute or chronic toxic effects due to the presence of
the constituents detected in soils or surface waters at SD-09. For additional details concern-
ing the findings of the baseline ecological risk assessment, consult the final report (IT,
1993d).
5.7 Remedial Action Decision Summary for OU-3
During the FS, PRGs were determined for chemicals in soil and groundwater at each OU-3
site. The PRGs for soil at sites FT-02 and SD-09 were established by considering base-
specific background concentrations, EPA Region IX PRGs, and Arizona HBGLs for soil.
Background concentration ranges for each chemical in soil were determined from surface soil
sampling at areas of the Base away from known or suspected contamination. The EPA
KN/3187/WP3187J/01-22-96(923«m)/DO/El 5-17
-------
Region DC PRGs are health-based concentrations that correspond to either a one in one
million (10"6) cancer risk or a chronic noncancer HQ of one, whichever is lower. Because
the ultimate land use of the OU-3 sites is unknown, the EPA Region IX PRGs selected for
use were based on a residential land-use scenario. This land-use scenario provides for the
most health-protective PRGs.
PRGs for groundwater at FT-02 were established by considering base-specific background
concentrations, federal and state primary and secondary drinking water standards. EPA
Region DC PRGs, and Arizona HBGLs.
After PRGs were determined for chemicals in the applicable environmental media at the OU-
3 sites, an analysis was performed to determine if these chemicals were present at concentra-
tions requiring remedial action. This evaluation involved comparing the upper confidence
limit (UCL) concentration of each chemical in soil and groundwater to its respective PRG.
Those chemicals with UCL concentrations exceeding the PRG were determined to be COCs
requiring remedial action. The PRGs for compounds determined to be COCs are enforceable
cleanup levels under this ROD.
A more detailed description of the process used to establish PRGs and identify COCs
requiring remedial action is presented in the Chapter 2.0 of the OU-3 FS report. Tables
summarizing the determination of COCs and their respective cleanup levels in soil and
groundwater for FT-02 and SD-09 are presented in Appendix A.
Sections 5.7.1 and 5.7.2 discuss the remedial action objectives (RAO), COCs, and cleanup
levels for soil and groundwater at FT-02 and SD-09. A summary of RAOs for OU-3 is
presented in Appendix A, Table A-4.
5.7.1 Fire Protection Training Area No. 2
5.7.1.1 Soil
Remedial action will be required for FT-02 soil. Three organic compounds (benzene,
chloroform, and 1,4-dichlorobenzene) were determined to be COCs for FT-02 soil because the
UCL concentration of each compound was greater than its respective PRG. Benzene,
chloroform, and 1,4-dichlorobenzene were detected in FT-02 soil at UCL concentrations of
7.3, 0.66, and 8.2 mg/kg, respectively. Benzene and chloroform are both VOCs. Benzene is
known to cause cancer in humans, and chloroform is categorized as a probable human
KN/3187/WP3187J/01-22-96(923ani)/DO/El 5-18
-------
carcinogen based on data from animal studies. 1,4-dichlorobenzene is an SVOC that is
categorized as a possible human carcinogen based on limited evidence of carcinogenicity in
animals. Based on the risk-based analyses presented in the OU-3 Rl/FS documents, the
following RAOs was established for FT-02 soil:
Protect human health and the environment by reducing the concentration of
benzene, chloroform, and 1,4-dichlorobenzene in FT-02 soils to 1.4, 0.53, and
7.4 mg/kg, respectively. The residual total ILCR for all chemicals in soil
summed across all exposure pathways will be within the acceptable risk range of
10"6 to 10"4. The reduction in organic contaminants will prevent the future
migration of contaminants to groundwater.
The concentrations listed in the RAO for each COCs are cleanup levels enforceable under the
ROD.
Actual or threatened releases of hazardous substances from this site, if not addressed by the
preferred alternative or one of the other active measures considered, may present a current or
potential threat to public health, welfare, or the environment.
5.7.1.2 Groundwater
Remedial action is not required for FT-02 groundwater because the UCL concentration of all
chemicals detected in groundwater were below PRGs. Therefore, no RAOs or cleanup levels
were established for FT-02 groundwater.
5.7.2 Southwest Drainage System (SD-09)
5.7.2.1 Soil
Remedial action is not required for SD-09 soil because the UCL concentration of all chemi-
cals detected in soil were below PRGs. Because the limited residual soil contamination is
distributed within the upper few feet of soil at the site, there is no evidence of a threat to
groundwater and remedial action is not required to protect groundwater. Therefore, no RAOs
or cleanup levels were established for SD-09 soil.
5.7.2.2 Groundwater
Remedial action is not required for SD-09 groundwater because there is no evidence of any
current or potential future environmental impact on groundwater based on the low concentra-
tion and shallow distribution of contaminants in the overlying soil. Therefore, no RAOs,
COCs, or cleanup levels were established for SD-09 groundwater.
KN/3187/WP31875y01-22-96(923am)/DO/El 5-19
-------
5.8 Summary and Conclusions
5.8.1 Current and Future Land Use
The Base closed on September 30, 1993 and is currently under control of the Air Force Base
Conversion Agency. The agency is working with the local community to maximize reuse for
aviation, education, commercial, and industrial purposes. The Base has been divided into
potential reuse parcels identified as airfield, commercial, aviation support, air cargo, general
industrial, education/research/training, institutional/medical, and schools. The golf course has
been leased; and other areas have been leased to the Williams Gateway Airport Authority and
the Arizona State University. Leases are being negotiated for several industrial areas. More
definitive reuse information is not available at this time.
5.8.2 Baseline Human Health Assessment
HI values greater than unity were estimated only for the SD-09, and were due almost entirely
to incidental ingestion of soil (current and future residential scenarios). The major contri-
butors were antimony, and to a lesser extent, arsenic, cadmium, chromium, and thallium.
However, as noted in Section 5.5.4, the contribution to the total HI due to antimony may be
disregarded as a laboratory artifact Also, the remaining HI, 9.9 x 10"1, was less than unity.
The total HI for individual target organs is also less than 1.0. As discussed in Section 5.5.6,
the chromium present was assumed to exist entirely in the hexavalent state, which is unlikely
for chromium released into the environment. The RfD for trivalent chromium (1 mg/kg-day)
is more than two orders of magnitude higher (less restrictive) than the RfD for hexavalent
chromium (5 x 10"3 mg/kg-day), suggesting that the HI for chromium is overly conservative.
None of the sites evaluated resulted in an BLCR for any one pathway greater than the upper
limit of the target risk range of 1 x 10~6 to 1 x 10"4. The following sites resulted in pathway
ILCRs within the target risk range:
Fire Protection Training Area No. 2 (FT-02)
- Inhalation of volatiles and fugitive dust from soil (future residential and
current occupational scenarios)
Southwest Drainage System (SD-09)
- Incidental ingestion of soil (current and future residential and current occupa-
tional scenarios)
KN/3187/WK187.5/01-22-%<9:23am)/DO/El 5-20
-------
- Inhalation of volatiles and fugitive dust (current and future residential and
current occupational scenarios).
When summed across pathways for a given medium (groundwater or soils) or for all media,
none of the receptors had a total ILCR greater than 1 x 10"4.
The primary contributors to risk in groundwater and soils include the following COPCs:
Groundwater
- Carbon disulfide, methylene chloride, zinc (FT-02)
SoU
- Benzene, chloroform, mercury, MEK (FT-02)
- Arsenic, beryllium, cadmium, chromium, thallium (SD-09).
The potential for future development of production wells in the plume is small even with the
Base decommissioned. A future residential scenario has been evaluated to provide an upper-
bound estimate of potential risks associated with exposure to this groundwater. These
potential risks exist only if a residential well is completed within FT-02 and a resident used
the water at the levels assumed in the exposure assessment for 30 years.
5.5.3 Ecological Assessment
There are extensive mechanical stresses at SD-09 related to maintenance mowing that have
held the area in a permanent state of arrested secondary succession with little native habitat.
Based on the data presented, and taking into consideration the uncertainties inherent in the
ecological assessment, the probability for adverse ecological effects occurring at the Base are
judged to be insignificant. It can be concluded that alteration of habitat by direct mechanical
stresses has had a more profound effect on areas at the Base than the COPC. A comprehen-
sive discussion of the findings of the baseline ecological risk assessment is presented in its
final report (TT, 1993d).
5.8.4 Remedial Action Decision Summary
It was determined that further remedial action is required for soil at FT-02 to reduce the
concentration of benzene, chloroform, and 1,4-dichlorobenzene in soils to health protective
levels, and reduce the total concentration of organic contaminants in soil to prevent any
KN/3187AVP3187^/01-22-96(923am)/DO/El 5-21
-------
potential future adverse impact to groundwater. It was determined that remedial action is not
required for FT-02 groundwater.
It was determined that no remedial action is required for SD-09 soils and groundwater.
KN/3187/WP3187.5A>l-22-96(9:23»m)/DO/El 5-22
-------
6.0 Description of Alternatives
Under CERCLA, a process has been established to develop, screen, and evaluate appropriate
remedial alternatives. A wide range of cleanup options were considered for remedial action
at FT-02. Remedial alternatives were not developed for SD-09 because this site does not
require remedial action.
The initial process options considered during the preliminary screening process are presented
in Figure 6-1. The process options were evaluated, and retained or eliminated from further
consideration on the basis of technical feasibility. Figure 6-1 presents the rationale for
eliminating process options.
A second screening step was then performed to evaluate the remaining process options on the
basis of implementability, effectiveness, and cost. The result of this screening process was
intended to select one representative process option for each technology type for detailed
analysis. The secondary screening was a two-step process. First, the process options retained
from preliminary screening were ranked according to the previously defined three criteria to
eliminate those options that were obviously inappropriate. The results of this step are
presented in Figure 6-2. The process options that remained after this step, shown in Table 6-
1, were then subjected to a more detailed evaluation based on the three criteria. After this
evaluation was completed, the following three alternatives for FT-02 soils were retained for
detailed analysis:
Alternative FT02-1: No Action
Alternative FT02-4: Soil Vapor Extraction
Alternative FT02-5: Bioventing.
These alternatives were developed based on site-specific needs and evaluated using the nine
criteria developed by EPA to address CERCLA requirements. The evaluation criteria
presented in Figure 6-3 are used to determine the most appropriate alternative. The following
sections present detailed descriptions of the two remedial alternatives for contaminated soils at
FT-02.
KN/3187/WP3187.6/01-22-96<9:33am)/DO/El 6-1
-------
General Response Action Technology Type
Process Option
Comments
No Action
Institutional Action
N/A
Land Use Restrictions
N/A
Deed Restrictions
Fencing, Signs
Containment
Capping
Impermeable Cap
Physical
Chemical
Rinlnffir.al
r
Soil Flushing
Soil Vapor Extraction
/ /Vjttij&afiory / /\
Oxidation
' / / tfy&ifof / /.
Rim/pntino
Not applicable below 30 feet
applicable for volatile organic contaminants
Excavation not practical at required depth
Excavation not practical at required depth
L
- Retained
\//////\ - Eliminated
Figure 6-1. Initial Screening - Soils at FT-02
-------
General Response Action Technology Type Process Option Implementabllity
NoAclion N/A N/A
1 Deed Restrictions
Institutional Action Land Use Restrictions
1 Fencing, Signs
Containment Capping I Impermeable La)
In Situ Treatment
| ' / f&\ F(H«hinp
H Physical
1 Soil Vapor Extrac
\//^///\ //j&p£f
Biological Bioventing
Easily implemented
Easily implemented
Easily implemented
er £a_ Implemcntable
/ / / of varying permeability. Will spread
soil and groundwater
Implementable. Field pilot
lo" test may be required.
/ '? '\ Potentially difficult to implement.
/ / /\ Difficult to transport oxidant
Oxidants will react with soils.
Implementable. Field pilot
tests required.
1 1 - Retained
Effectiveness
Not Effective
Somewhat Effective
Somewhat Effective
Somewhat Effective
Potentially effective. May require
injection of environmentally significant
chemicals to improve the solubility
of contaminants.
Effecive for remediation
of fuel hydrocarbons in reasonably
permeable soils.
Effectiveness as an in situ
process for treating organic
compounds in soil has not been
demonstrated.
Effectiveness depends on site-specific
characteristics such as microbial
population, soil moisture, pH, nutrients,
presence of toxicants. Effective for
for removal of biodegradable organic
compounds.
Economics
Low
Low
Low
Moderate
Expensive. Significant groundwater
extraction and treatment system
required.
Economical method of remediating
vadose zone. Normally requires
air pollution controls.
Potentially expensive. Large amounts
of oxidizing agents may be required.
Economical method of remediating
vadose zone. May not require
air pollution controls.
\ / / / / / A - Eliminated
Figure 6-2. Secondary Screening - Soils at FT-02
fig2-4fl2.drw/1ld/l2-21-94
-------
Table 6-1
FT-02 Soil Alternatives for Inclusion in the Screening Process
Williams Air Force Base
Alternative
FT02-1
FT02-2
FT02-3
FT02-4
FT02-5
Description
No action
Institutional action
Capping
Soil Vapor Extraction
Bbventing
KN/3187/WP31 87.6-l/01-22-96(9:35im)/DO/El
-------
THRESHOLD CRITERIA
OVERALL PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
Requires the assessment of alternatives to determine how they will
provide human health and environmental protection from the risks
present at a site by eliminating, reducing or controlling the
hazardous material detected during the Remedial Investigation.
COMPLIANCE WITH ARARs
Requires the assessment of alternatives to
determine how they meet the requirements
under federal environmental laws and state
environmental or facility siting laws.
PRIMARY BALANCING CRITERIA
LONG-TERM EFFECTIVENESS AND PERMANENCE
This criterion requires the evaluation of residual
risks remaining at a site after completion of the
remedial action.
SHORT-TERM EFFECTIVENESS
This criterion evaluates a remedial
alternative's impact on human health and
the environment during implementation.
REDUCTION OF TOXICITY. MOBILITY. AND VOLUME
This criterion addresses the statutory preference for selecting
remedial actions that permanently and significantly reduce the
toxicity, mobility, or volume of hazardous substances at a site by
evaluating the extent to which this is achieved by each alternative.
IMPLEMENTABILITY
This criterion evaluates both the
technical and administrative feasibility
of implementing an alternative including
the availability of key services and
material required during its implementation.
COST
Under this criterion, capital costs,
annual operation and maintenance
costs and the net present value of
capital O&M costs are assessed for
each alternative.
MODIFYING CRITERIA
STATE ACCEPTANCE
This criterion addresses the statutory requirement for
substantial and meaningful state involvement.
Evaluation of this criterion is conducted by U.S. EPA and
addressed during development of the Record of Decision.
COMMUNITY ACCEPTANCE
This criterion assesses the community's apparent
preference for, or concerns about, the remedial
alternatives. This process is conducted by U.S. EPA and
addressed during development of the Record of Decision.
KN/FIQ6-3.XLS/B-18-95/F
Figure 6-3. Remedial Alternative Evaluation Criteria
-------
6.1 Alternative FT02-1: No Action
6.1.1 Source Treatment Component
The alternative does not incorporate a treatment component that would result in a permanent
reduction of the toxicity or volume of soil contaminants. The no action alternative is
included in accordance with the NCP to serve as a baseline for comparison with other
alternatives. This alternative would leave approximately 25,000 cubic yards of contaminated
soils in place with no additional means to prevent human exposure or migration of contami-
nants to groundwater. FT-02 soils are contaminated with 2 to 310 mg/kg benzene, 1 to 2
mg/kg chloroform, and 2 to 120 mg/kg 1,4-dichlorobenzene. The alternative does include
annual groundwater monitoring for specified COPCs.
6.1.2 Source Containment Component
The alternative does not incorporate a containment component that would restrict the
migration of contaminants from soil to groundwater.
6.1.3 Groundwater Component
The remedial alternative does not incorporate a groundwater extraction and treatment
component.
The remedial alternative does provide for institution of a 30-year groundwater monitoring
program with data collected and analyzed annually to ensure the protection of public health
and the environment by confirming that groundwater quality is not being adversely affected
by the future migration of soil contaminants. A monitoring program would be established in
accordance to with the requirements of 40 Code of Federal Regulations (CFR) 264.91-100 to
analyze for specified constituents and/or indicator parameters. Annual groundwater moni-
toring data would be provided to the regulatory agencies. The details of the groundwater
monitoring program would be established during the remedial design/remedial action
(RD/RA) phase.
6.1.4 General Components
No institutional controls will be utilized in the implementation of this alternative. Ground-
water at the site would be sampled annually and analyzed for specified chemicals and/or
indicator parameters.
There are no implementation requirements of concern for this alternative.
KN/3187/WP3187.6/01-22-96<9:33«m)/DO/El 6-2
-------
The initial risk in implementing the remedial alternative is very low because no remedial
action would be taken at the site that could create potential exposures.
The residual risk for this alternative is higher than for the other alternatives because no action
would be taken to prevent the migration of contaminants to groundwater. Long-term
groundwater monitoring would be required to ensure that contaminants left in place do not
impact groundwater.
There are no capital costs associated with this alternative. Annual operation and maintenance
(O&M) costs are $0.04 million, which represents the cost of groundwater monitoring and 5-
year site reviews. The estimated net present worth of this alternative is $0.9 million.
Detailed cost information for Alternative FT02-1 is presented in Appendix B of this document
and Appendix E.I of the OU-3 FS report.
6.1.5 Compliance with ARARs
Because this alternative does not incorporate any active remedial measures, applicable or
relevant and appropriate requirements (ARAR) are not applicable.
6.2 Alternative FT02-4: Soil Vapor Extraction
6.2.1 Source Treatment Component
This alternative would volatilize contaminants from the subsurface by imposing a vacuum on
the subsurface soils through a series of vadose zone extraction wells. The contaminants in
the extracted soil gas would subsequently be destroyed by a fume incineration system. A
typical process flow diagram for a soil vapor extraction (SVE) system is presented in Figure
6-4.
The alternative would treat in situ approximately 25,000 cubic yards of soil contaminated
with benzene, chloroform, and 1,4-dichlorobenzene at concentrations in excess of cleanup
levels. The alternative would reduce the soil concentration of benzene to 1.4 mg/kg, chloro-
form to 0.53 mg/kg, and 1,4-dichlorobenzene to 7.4 mg/kg. This would result in the removal
of approximately 181 kilograms (kg) of benzene, 4 kg of chloroform, and 25 kg of 1,4-
dichlorobenzene from FT-02 soils. Other volatile components of JP-4 would also be extracted
and destroyed during the operation of the SVE system. The removal of organic contaminants
from the soil would prevent the migration of soil contaminants to groundwater.
KN/3187/WP3187.6/01-22-96(9:33am)/DO/El 6-3
-------
TREATED VAPOR
TO ATMOSPHERE
SUBMERSIBLE
PUMP
Q
1
VACUUM
BLOWER
COMBUSTION
AIR BLOWER
FUME
INCINERATOR
- AUXILIARY FUEL
(NATURAL GAS
OR PROPANE)
CONDENSED WATER
CONTAINER
(TO TREATMENT)
FIGURE 6-4
SOIL VAPOR EXTRACTION (SVE) SYSTEM
CONCEPTUAL FLOW DIAGRAM
FIRE PROTECTION TRAINING AREA
NO. 2 (FT-02) SOILS
OU-3. WILLIAMS AFB
CTm INTERNATIONAL
I H TECHNOLOGY
ImU CORPORATION
-------
Based on data currently available, the SVE system is expected to require the installation of
nine soil gas extraction wells at depths varying from 10 to 86 feet deep. One well at the
large burn pit would be connected to a vacuum blower rated for 40 standard cubic feet per
minute (scfm) at 10 inches of mercury vacuum. The remaining extraction wells to be located
at the small burn pit would be manifolded to a vacuum blower rated for approximately 500
scfm at 18 inches of mercury. The fume incinerator would be designed to treat the combined
emissions from both SVE blowers. The fume incinerator is estimated to be rated for 3
million British Thermal Units (Btu) per hour. The size and configuration of the SVE system
components would be finalized during remedial design after an SVE pilot test is completed at
the site.
6.2.2 Source Containment Component
The alternative does not incorporate a containment component that would restrict the
migration of contaminants from soil to groundwater. A containment component is not
required because the treatment component would effectively remediate the contaminated soils.
6.2.3 Groundwater Component
The remedial alternative does not incorporate a groundwater extraction and treatment
component because groundwater is not currently contaminated. Groundwater monitoring
would not be required after the concentration of COCs in soil are reduced to cleanup levels.
6.2.4 General Components
The initial cancer and noncancer risks for contaminated soils at FT-02 are within acceptable
levels. The total ILCR for future residents of the site from exposure to all chemicals in FT-
02 soil summed across all exposure pathways is 3.4 x 10"5. The total noncancer HI is 0.94.
However, the concentration and distribution of contaminants in the soil presents a future
threat to groundwater quality. The reductions in soil concentrations achieved through SVE
treatment would prevent the future migration of contaminants to groundwater.
There are no major implementation concerns associated with the construction and operation of
an SVE system. The units operate with limited operator attention. Periodic monitoring of the
fume incinerator emissions may be required to confirm compliance with Maricopa County air
quality standards.
No institutional controls would be required as a component of this alternative.
KN/3187/WP3187.6A>l-22-96<9:33am)/DO/El 6-4
-------
The alternative is expected to require 2 years to achieve cleanup levels in soil.
The initial capital cost of this alternative is estimated to be $0.8 million. Annual O&M costs
are estimated to be approximately $0.3 million. The net present worth cost of this alternative
is estimated to be $1.2 million. Detailed cost information for Alternative FT02-4 is presented
in Appendix B of this document and Appendix E.I of the OU-3 FS report.
6.2.5 Compliance with ARARs
No chemical-specific ARARs exist for COCs in soils. This alternative would meet all
applicable location- and action-specific ARARs listed in Appendix C.
The location-specific ARAR concerning the protection of significant archaeological artifacts is
a relevant and appropriate requirements. Prior to the initiation of any remedial activities at
the site, remedial plans will be reviewed with the State Historic Protection Officer (SHPO) to
obtain his approval. If any obvious archaeological artifacts are encountered during remedial
operations, work will be stopped and the SHPO will be consulted. Through these actions,
Alternative FT02-4 would comply with the archaeological ARAR.
The action-specific ARAR concerning surface water control is considered relevant and
appropriate. The alternative will meet this requirement by providing storm water collection in
areas where soil cuttings are stored.
The action-specific ARAR concerning on-site container storage is an applicable requirement.
The alternative will comply with the requirements of RCRA Section 40 CFR 264 concerning
the handing, inspection, and maintenance issues associated with the storage of soil cuttings
and water extracted from the subsurface by the SVE system.
The action-specific ARAR concerning air emissions during remediation is an applicable
requirement. This requirement will be met through the installation and use of a fume
incineration system to reduce the concentration of organic vapors in soil gas extracted by the
SVE system. The fume incinerator would be designed, operated, and maintained to ensure
compliance with this ARAR.
The action-specific ARAR concerning the treatment of extracted soil moisture will be met by
containerizing the water in a 55-gallon drum or a tote tank for subsequent transport to and
treatment by the ST-12 groundwater treatment system. Currently, the treated groundwater at
KN/3187/WP3187.6/01-22-96{9:33ajn)/DO/El 6-5
-------
ST-12 is discharged to the sanitary sewer and must comply with pretreatment limits in the
Base's permit with the local publicly owned treatment works. In the future, the treated water
may be reinjected at ST-12. At that time, the treated water would have to comply with
reinjection standards.
6.3 Alternative FT02-5: Bioventing
6.3.1 Source Treatment Component
This alternative delivers oxygen to contaminated soils by forced air injection to stimulate
aerobic metabolism of organic contaminants by indigenous soil microorganisms. A blower
would inject air into the soil through a series of air injection wells screened in the contami-
nated soil. The air would be supplied to the soil at rates that would provide sufficient oxygen
to stimulate biodegradation while minimizing volatilization and release of contaminants to the
atmosphere. A typical process flow diagram for a bioventing system is presented in Figure
6-5.
The alternative would treat in situ approximately 25,000 cubic yards of soil contaminated
with benzene, chloroform, and 1,4-dichlorobenzene at concentrations in excess of cleanup
levels. The alternative would reduce the soil concentration of benzene to 1.4 mg/kg, chloro-
form to 0.53 mg/kg, and 1,4-dichlorobenzene to 7.4 mg/kg. This would result in the removal
of approximately 181 kg of benzene, 4 kg of chloroform, and 25 kg of 1,4-dichlorobenzene
from FT-02 soils. Other biodegradable components of JP-4 would also be converted to
innocuous chemicals such as carbon dioxide and water. The removal of organic contaminants
from the soil would prevent the migration of soil contaminants to groundwater.
Based on data currently available, the bioventing system is expected to require the installation
of nine air injection wells at depths varying from 10 to 86 feet deep. All nine wells would be
connected to a 200 scfm blower rated for 10 pounds per square inch gage (psig) pressure.
Due to the proposed configuration of the bioventing system, it is estimated that air pollution
controls would not be required because the potential for volatile emissions is very low. The
bioventing system will use a low rate of air injection (less than 1 scfm per foot of vent well
screen). Because horizontal permeability is generally greater than vertical permeability, the
injected air will tend to move outward rather than upward. This will promote in-situ
biodegradation of organic vapors as they move slowly outward from the injection point.
KN/3187/WP3187.6/01-22-96(9:33am)/DO/El 6-6
-------
AMBIENT
AIR
BLOWER
AIR TO
CONTAMINATED
SOIL PORE SPACE
AIR INJECTION
WELL SYSTEM
SOIL CAS
MONITORING
MICROORGANISMS
DEGRADE CONTAMINANTS
FIGURE 6-5
BIOVENTING SYSTEM
CONCEPTUAL FLOW DIAGRAM
FIRE PROTECTION TRAINING AREA
NO. 2 (FT-02) SOILS
OU-3, WILLIAMS AFB
INTERNATIONAL
TECHNOLOGY
CORPORATION
-------
The size and configuration of the bioventing system components would be finalized during
remedial design after a bioventing pilot test is completed at the site.
6.3.2 Source Containment Component
The alternative does not incorporate a containment component that would restrict the
migration of contaminants from soil to groundwater. A containment component is not
required because the treatment component would effectively remediate the contaminated soils.
6.3.3 Groundwater Component
The remedial alternative does not incorporate a groundwater extraction and treatment
component because groundwater is not currently contaminated. Groundwater monitoring
would not be required after the concentration of COCs in soil are reduced to cleanup levels.
6.3.4 General Components
The initial cancer and noncancer risks for contaminated soils at FT-02 are within acceptable
levels. The total ILCR for future residents of the site from exposure to all chemicals in FT-
02 soil summed across all exposure pathways is 3.4 x 10 . The total noncancer HI is 0.94.
However, the concentration and distribution of contaminants in the soil presents a future
threat to groundwater quality. The reductions in soil concentrations achieved through
bioventing treatment would prevent the future migration of contaminants to groundwater.
There are no major implementation concerns associated with the construction and operation of
a bioventing system. The units operate with limited operator attention. Initial monitoring of
ambient air in the vicinity of the treated soils will be required to confirm compliance with
Maricopa County air quality standards.
No institutional controls would be required as a component of this alternative.
The alternative is expected to require 4 years to achieve cleanup levels in soil.
The initial capital cost of this alternative is estimated to be $0.6 million. Annual O&M costs
are estimated to be approximately $0.1 million. The net present worth cost of this alternative
is estimated to be $1.1 million. Detailed cost information for Alternative FT02-5 is presented
in Appendix B of this document and Appendix E.I of the OU-3 FS report.
KN/3I87/WP3187.6/01-22-96<9:33tnO/DO/El 6-7
-------
6.3.5 Compliance with ARARs
No chemical-specific ARARs exist for COCs in soils. This alternative would meet all
applicable location- and action-specific ARARs listed in Appendix C. The location-specific
ARAR concerning the protection of significant archaeological artifacts is a relevant and
appropriate requirement. Prior to the initiation of any remedial activities at the site, remedial
plans will be reviewed with the SHPO to obtain his approval. If any obvious archaeological
artifacts are encountered during remedial operations, work will be stopped and the SHPO will
be consulted. Through these actions, Alternative FT02-4 would comply with the archaeologi-
cal ARAR.
The action-specific ARAR concerning surface water control is considered relevant and
appropriate. The alternative will meet this requirement by providing storm water collection in
areas where soil cuttings are stored.
The action-specific ARAR concerning on-site container storage is an applicable requirement.
The alternative will comply with the requirements of RCRA Section 40 CFR 264 concerning
the handing, inspection, and maintenance issues associated with the storage of soil cuttings.
The action-specific ARAR concerning air emissions during remediation is an applicable
requirement. It is anticipated that emission controls will not be required to comply with this
ARAR because emissions from the bioventing system should be below limits specified by the
Maricopa County Air Pollution Control Division. To ensure compliance, a surface emission
monitoring program will be initiated following start-up. Surface emissions will be monitored
using flux chambers. Air samples collected will be analyzed for BTEX and total volatile
hydrocarbons (TVH) by EPA method TO-3. If total hydrocarbon emissions approach the 3-
pound per day limit, the air injection rate will be reduced.
The action-specific requirement concerning treatment of extracted soil moisture is not an
ARAR for the bioventing alternative because soil gas will not be mechanically extracted.
KN/3187/WP3187.6A>l-22-96(9:33am)/DO/El 6-8
-------
7.0 Comparative Analysis of Alternatives
The final phase in the evaluation of remedial alternatives involves a comparison of the
various alternatives. The advantages and disadvantages of each alternative are reviewed
relative to each of the nine EPA evaluation criteria presented in Figure 6-3. The following
sections present the evaluation process for FT-02. Site SD-09 does not require remedial
action and, therefore, is not discussed in this section. For each evaluation criterion discussed,
the apparent best alternative is identified first. Table 7-1 summarizes the results of the
remedial alternative evaluation process for FT-02.
7.1 Overall Protection of Human Health and the Environment
Both Alternatives FT02-4 and FT02-5 should reduce the soil concentrations of benzene,
chloroform, and 1,4-dichlorobenzene to cleanup levels. Treatability studies/pilot tests are
recommended to confirm the effectiveness of both technologies. SVE and bioventing would
both have the additional treatment benefit of reducing the concentrations of other organic
contaminants, thereby preventing the migration of contaminants to groundwater. The no-
action Alternative FT02-1 would not provide long-term protection of human health and the
environment because it would not reduce the concentration of contaminants in the soil.
7.2 Compliance with ARARs
Alternatives FT02-4 and FT02-5 should meet all applicable location-specific and action-
specific ARARs as presented in Appendix C. No chemical-specific ARARs exist for soils.
EPA does not consider Alternative FT02-1 to be a "remedial action" because no action is
being taken. Therefore, the requirements of CERCLA Section 121 concerning ARARs do not
apply to Alternative FT02-1, and ARARs are not identified.
7.3 Long-Term Effectiveness and Permanence
Because Alternatives FT02-4 and FT02-5 would both reduce the concentrations of COCs in
soil to cleanup levels, they would provide permanent and equivalent reductions in the residual
risks associated with the site, such as exposure to contaminated soil and migration of
contaminants to groundwater. The attainment of cleanup levels under either alternative would
reduce any residual risk to acceptable levels.
KN/3187/WP3187.7A>l-22-96(9:36am)/DO/El
-------
Table 7-1
Comparison of Cleanup Alternatives
Fire Protection Training Area No.2 (FT-02), OU-3
Williams Air Force Base
EPA Evaluation Criteria
Overall Protection of Human Health
and the Environment
Compliance with ARARs
Long-Term Effectiveness and
Permanence
Reduces Toxicity, Mobility or
Volume
Short-Term Effectiveness
Implementability
Cost (Present worth)
State Acceptance
Community Acceptance
Estimated Remedial Duration (years)
FT02-1 No Action
Not Protective
Not applicable
Not a permanent solution
No reduction
Not effective
Most implementable
$0.9 million
>30
FT02-4 Soil Vapor Extraction
Protective
Complies
Achieves a permanent and effective
solution
Reduces toxicity and mobility of
contaminants
Effective
Easily implementable
$1.2 million
--
--
2
FT02-5 Bioventing
Protective
Complies
Achieves a permanent and effective
solution
Reduces toxicity and mobility of
contaminants
Effective
Easily implementable
$1.1 million
Acceptable8
Acceptable3
4
aNo comments were received from the State of Arizona or the community concerning the implementation of the bioventing remedy at the public meeting or during
the public comment period.
KN/3187/WP3187.7-l/01-22-96(10:08«m)/DO/El
-------
Alternative FT02-1 would not provide any long-term effectiveness or permanence because
there would be no reduction in risk associated with human exposures or migration of
contaminants to groundwater.
7.4 Reduction in Toxicity, Mobility, and Volume Through Treatment
Alternative FT02-4 could provide greater reduction of chloroform concentrations than
Alternative FT02-5 because this compound is somewhat biologically resistant, but readily
volatilized. Although volatilization is not the primary pathway of contaminant removal for
bioventing, reductions in chloroform concentrations would occur via this route. Treatability
testing prior to the implementation of Alternative FT02-5 would verify the effectiveness of
bioventing in reducing chloroform and 1,4-dichlorobenzene concentrations. Both alternatives
should provide approximately equivalent reductions in benzene and 1,4-dichlorobenzene
concentrations. Although 1,4-dichlorobenzene is somewhat resistant to biological degradation
and, therefore, less amenable than nonchlorinated organics to treatment via bioventing, it is
also a semivolatile compound that is not as readily volatilized as VOCs such as benzene and
chloroform. Both alternatives provide a reduction in the concentration of other soil contami-
nants not requiring remedial action to meet cleanup levels, thereby preventing the migration
of contaminants to groundwater. Both Alternatives FT02-4 and FT02-5 are essentially equally
effective in reducing the mobility of soil contaminants. Alternative FT02-1 would provide no
reduction in the mobility of contaminants or the volume of contaminated soil, although some
reduction in toxicity could occur over time due to natural attenuation processes.
7.5 Short-Term Effectiveness
Alternative FT02-1 would pose no additional short-term risks to the general public, workers,
or the environment. Alternative FT02-5 would pose slightly fewer short-term risks than
Alternative FT02-4 because bioventing systems are designed to minimize the volatilization of
contaminants and, therefore, do not typically require emission controls. SVE promotes the
volatilization of contaminants, which would be drawn aboveground to be treated via fume
incineration or carbon adsorption prior to discharge to the atmosphere. The enhanced short-
term risk associated with SVE arises from the potential malfunction or failure of the air
pollution control equipment, which could result in increased exposure to VOC contaminants
by site workers and temporary noncompliance with air quality standards.
7.6 Implementability
Alternative FT02-1 has no attendant implementability concerns. Alternatives FT02-4 and
FT02-5 are both readily implementable, with FT02-5 projected to require an additional 2
KN/3187/WP3187.7A)l-22-96<9:36im)/DO/El 7-2
-------
years to complete over FT02-4. While O&M requirements are not significant for either
alternative, air pollution control equipment is not required for Alternative FT02-5; therefore,
O&M requirements for this alternative are correspondingly lower.
7.7 Cost
Table 7-2 summarizes the estimated capital costs, O&M costs, and present worth costs for the
three alternatives. At $0.9 million, the no-action Alternative FT02-1 has the lowest net
present worth. Between the two alternatives involving treatment, alternative FT02-5 has a net
present worth of $1.1 million, while Alternative FT02-4 has a net present worth of $1.2
million. Alternative FT02-5 is less expensive than Alternative FT02-4 because bioventing
does not require the installation of air pollution control equipment.
KN/3187AVP3187.7/Bl-22-96(9:36un)/DO/El 7-3
-------
Table 7-2
Summary of Remedial Alternative Cost Estimates
Fire Protection Training Area No. 2 (FT-02), OU-3
Williams Air Force Base
Cost Component3
Capital Cost
Annual Operating and
Maintenance Cost (O&M)
Present Worth Cost
FT02-1
No Action
($)
0
0.04
0.9
FT02-4
Soil Vapor Extraction
($)
0.8
0.3
1.2
FT02-5
Bioventing
($)
0.6
0.1
1.1
a All cost figures are reported in millions. A 5 percent discount rate and 30 years was used to
calculate present worth costs.
KN/3187/WP3187.7-2/01-22-96(10.-09am)/D(VEl
-------
-------
8.0 Selected Remedy
The selected remedy for FT-02 is Alternative FT02-5: Bioventing. The specific components
of this alternative are presented in Section 6.2 and described in this section.
Alternative FT02-5 satisfies the two threshold criteria, overall protection of human health and
the environment and compliance with ARARs, and provides the best balance of the nine
evaluation criteria presented in Figure 6-3. The selected remedy will provide the greatest
level of effectiveness that is technically and economically feasible. The criterion of protec-
tion of human health and the environment is appropriately balanced with both effectiveness
and technical/economic feasibility.
8.1 Major Components of the Selected Remedy
This alternative delivers oxygen to contaminated soils by forced air injection to stimulate
aerobic metabolism of organic contaminants by indigenous soil microorganisms. A blower
will inject air into the soil through a series of air injection wells screened in the contaminated
soil. The air will be supplied to the soil at rates that will provide sufficient oxygen to
stimulate biodegradation while minimizing volatilization and release of contaminants to the
atmosphere. Therefore, emission controls are typically not required with bioventing systems.
A typical process flow diagram for a bioventing system is presented in Figure 6-5.
The alternative would treat in situ approximately 25,000 cubic yards of soil contaminated
with benzene, chloroform, and 1,4-dichlorobenzene at concentrations in excess of cleanup
levels. The alternative would reduce the soil concentration of benzene to 1.4 mg/kg, chloro-
form to 0.53 mg/kg, and 1,4-dichlorobenzene to 7.4 mg/kg. These cleanup levels are based
on EPA Region DC PRGs, which are risk based. These contaminant reductions would result
in the removal of approximately 181 kg of benzene, 4 kg of chloroform, and 25 kg of 1,4-
dichlorobenzene from FT-02 soils. The residual human health risks remaining after remedial
action is complete at FT-02 will be within the 10"6 to 10"4 acceptable risk range. Other
biodegradable components of JP-4 would also be converted to innocuous chemicals such as
carbon dioxide and water. The general reduction in the concentration of organic compounds
in the soil will also prevent the migration of soil contaminants to groundwater.
Based on data currently available, the bioventing system is expected to require the installation
of nine air injection wells at depths varying from 10 to 86 feet deep. All nine wells will be
KN/3187/WP3187.8A)l-22-96<9:3&m)/DO/El 8-1
-------
connected to a 200 scfm blower rated for 10 psig pressure. Due to the proposed configura-
tion of the bioventing system, it is estimated that air pollution controls would not be required
because the potential for volatile emissions is very low. The bioventing system will use a
low rate of air injection (less than 1 scfm per foot of vent well screen). Because horizontal
permeability is generally greater than vertical permeability, the injected air will tend to move
outward rather than upward. This will promote in-situ biodegradation of organic vapors as
they move slowly outward from the injection point. The size and configuration of the
bioventing system components will be finalized during remedial design after a bioventing
pilot test is completed at the site.
Soil and soil gas monitoring will be conducted periodically during the operation of the
bioventing system to evaluate the effectiveness of the remedial action and determine when
RAO-based cleanup levels have been met for COCs. Respiration tests will be conducted
every 6 months to measure bioactivity as determined by the rate of oxygen consumption.
Soil gas samples will be collected annually and analyzed for BTEX and TVH by EPA method
TO-3. Soil samples will be collected annually adjacent to vent wells and at selected
monitoring points and analyzed for total recoverable petroleum hydrocarbons, VOCs, and
moisture content. The analysis for VOCs will include benzene, chloroform, and 1,4-dichloro-
benzene. Monitoring points in the vadose zone shall be determined during the RD/RA
process.
Because bioventing will reduce the concentration of soil contaminants such that the use of
and exposure to the site is not restricted, a 5-year review will not be required unless the
remedial action is not fully complete within 5 years of its initiation.
8.2 Implementation Concerns
There are no major implementation concerns associated with the construction and operation of
a bioventing system. The units operate with limited operator attention. Initial monitoring of
ambient air in the vicinity of the treated soils will be required to confirm compliance with
Maricopa County air quality standards. Periodic soil gas monitoring and in situ respiration
tests will be required to monitor the progress of remediation. Soil samples will be collected
and analyzed at the end of the remedial action to confirm that RAO-based cleanup levels have
been met for COCs. A bioventing pilot test will be conducted prior to remedial design.
Some changes may be made to the remedy as a result of additional information gathered
before, during, or after remedial design. However, these changes in general reflect modifica-
tions to the remedy resulting from the engineering design process.
KN/3187/WP31S7.8/01-22-96(9:36am)/DO/El 8-2
-------
The alternative is expected to require 4 years to achieve cleanup levels in soil.
8.3 Cost
The initial capital cost of this alternative is estimated to be $0.6 million. This cost includes
all equipment and installation costs associated with engineering, the bioventing pilot test, and
the installation of the air injection well network, associated piping, piezometers, and the
bioventing blower skid. Annual O&M costs are estimated to be approximately $0.1 million.
These costs represent primarily the operating labor, maintenance, utilities, and analytical work
necessary for the efficient operation of the bioventing treatment system. The net present
worth cost of this alternative is estimated to be $1.1 million. This relates to a total unit cost
of approximately $44 per cubic yard for the 25,000 cubic yards of contaminated soil treated
in situ.
KN/3187/WP3187.8A)l-22-96(9:36m)/DO/El 8-3
-------
-------
9.0 Statutory Determinations
Under Section 121 of CERGLA, the selected remedy must be protective of human health and
the environment and must comply with all ARARs. The selected remedy also must be cost-
effective and utilize permanent solutions and alternative treatment technologies to the
maximum extent practicable. Remedies that employ treatment that permanently and
significantly reduce the volume, toxicity, or mobility of hazardous wastes as a major part of
the remedy are preferable. How the selected remedy meets these requirements is discussed in
this chapter.
The State of Arizona and the communities surrounding Williams AFB were involved in the
determination of the selected remedy. The state was represented in the process by ADEQ and
ADWR, both of whom are parties to the FFA. They have been intrinsically involved in the
review and approval of all documents and decisions concerning the various stages of the
remedial process, including all work plans, RI/FS reports, proposed plans, and RODs.
The communities surrounding Williams AFB have been involved in the decision-making
process through the TRC, the RAB, and through public meetings and comment periods on
proposed remedies and removal actions. Chapter 11.0 of this document addresses the
communities' involvement in more depth.
Alternative FT02-5, bioventing, was chosen as the selected remedy. The selected remedy
represents the best balance among alternatives with respect to the pertinent criteria, given the
scope of this action.
9.1 Protection of Human Health and the Environment
The selected remedy protects human health by reducing the concentration of the three COCs
in FT-02 soils (benzene, chloroform, and 1,4-dichlorobenzene) via bioventing to cleanup
levels. The RAO for FT-02 sets the following cleanup levels for COCs in soils: 1.4 mg/kg
for benzene, 0.53 mg/kg for chloroform, and 7.4 mg/kg for 1,4-dichlorobenzene. These
cleanup levels ensure that the individual constituent ILCR for each chemical of concern will
be reduced to 10"6. The total residual ILCR remaining after the remedial action is complete,
determined for all chemicals summed across all exposure pathways, will be within EPA's
acceptable risk range of 10"6 to 10"4. The total residual noncancer HI for the site will be less
than 1.0. Bioventing the contaminated soils will also reduce the concentration of other
biodegradable constituents of JP-4, thereby preventing the future migration of organic soil
KN/3187/WP3187.9A)l-22-96{937am)/DO/El 9-1
-------
contaminants to groundwater. There are no short-term threats associated with the selected
remedy that cannot be readily controlled. In addition, no adverse cross-media impacts are
expected from the remedy.
9.2 Attainment of ARARs
The selected remedy will comply with all ARARs. These ARARs are presented in Appendix
C. A detailed discussion of how the remedy will comply with ARARs is presented in Section
6.3.5.
9.3 Cost Effectiveness
The selected remedy (bioventing) was evaluated for cost effectiveness against Alternative
FT02-1 (no action) and Alternative FT02-4 (SVE). Although the selected remedy is more
expensive than the no-action alternative, the no-action alternative is not protective of human
health and the environment, principally because of the potential future risk of contaminant
migration to groundwater. Bioventing was also determined to be more cost effective than
SVE because of its lower estimated present value cost.
9.4 Utilization of Permanent Solutions and Alternative Treatment Technologies
or Resource Recovery Technologies to the Maximum Extent Possible
The selected remedy (bioventing) utilizes permanent solutions and treatment technologies to
the maximum extent practicable. It is the remedial alternative that represents the optimum
balance among the alternatives with respect to the nine EPA evaluation criteria, especially the
balancing criteria of short-term effectiveness, implementability, and cost. Both bioventing
and SVE are approximately equivalent in terms of their long-term effectiveness and
permanence, and the degree to which they achieve reductions in the toxicity, mobility, or
volume of contamination through treatment. However, unlike an SVE system, a bioventing
treatment system will not extract contaminants from the subsurface for ultimate destruction in
an aboveground treatment unit, such as a fume incinerator. Therefore, site workers and the
public have a lower risk of exposure to uncontrolled emissions, in comparison to an SVE
system. Because air pollution controls are not required, a bioventing system is more easily
implemented than an SVE system. It requires less installation and start-up effort, as well as
less maintenance and emissions testing. The preferred remedy also has a lower present worth
cost than the SVE alternative. Although bioventing is estimated to require 2 years more than
SVE to remediate the site, the additional cost required for the SVE alternative is not
warranted because the current human health risks at the site are within acceptable levels, and
KN/3187/WP3187.9A)l-22-96(9:37ffln)/DO/El 9-2
-------
it is improbable that soil contaminants will impact groundwater over this additional 2-year
period.
The ADEQ and ADWR were involved at each step in the remedy selection process for OU-3,
reviewing and approving the EE/CA, RI/FS, proposed plan, proposed plan fact sheet, and the
ROD.
The public was invited to offer comment at each step in the process through public comment
periods advertised in local newspapers and at a public meeting. A fact sheet providing a
condensed version of the remedy selection process contained in the proposed plan was
distributed to the media along with a news release and to those who attended the public
meeting. In addition, the proposed plan and the proposed plan fact sheet were placed in the
information repository located at the Gilbert Public Library. The RAB was briefed on the
selected remedy for OU-3.
9.5 Preference for Treatment as a Principal Element
By treating the contaminated soils in situ via bioventing, the selected remedy addresses the
principal threats posed by the site through the use of a treatment technology. Therefore, the
statutory preference for remedies that employ treatment as a principal element is satisfied.
KN/3187/WP3187.9A)l-22-96(9:37im)/DOyEl 9-3
-------
-------
10.0 Documentation of Significant Changes
The proposed plan for OU-3 was released for public comment on June 26, 1995 and a public
meeting was held on July 18, 1995. The OU-3 proposed plan identified bioventing as the
preferred alternative for FT-02, and no further action as the preferred alternative for SD-09.
No written or verbal comments were received during the public comment period, and the
USAF, EPA, and the State of Arizona determined that no significant changes were necessary
to the preferred alternatives for the two sites, as originally identified in the proposed plan.
KN/3187/WP3187.10/01-22-96(1 ft04«m)/DO/El
-------
-------
11.0 Responsiveness Summary
11.1 Overview
The USAF published the proposed plan for cleanup of the groundwater and soil at Operable
Unit 3 (OU-3), Williams AFB in June 1995; the public comment period began June 26, 1995
and extended through July 25, 1995. A public meeting was held at the Centennial Con-
ference Center in Mesa, Arizona to present the plan to the public on July 18, 1995. The
preferred alternative specified in the ROD involves in situ treatment of the contaminated soil
via bioventing. The bioventing system will inject air into the subsurface soil to stimulate the
biodegradation of organic contaminants by indigenous soil microorganisms. The bioventing
system will be designed to comply with the applicable Maricopa County air quality require-
ment concerning volatile organic compounds emissions during remediation. The bioventing
system will operate until the concentrations of benzene, chloroform, and 1,4-dichlorobenzene
in the soils are reduced to cleanup levels.
The public meeting held on July 18, 1995 was poorly attended and no comments or questions
were received.
11.2 Background on Community Involvement
To date, the level of community interest and concern regarding the groundwater and soil
contamination at OU-3 in particular and environmental cleanup in general at Williams AFB
can be characterized as extremely low. In contrast, base re-use issues have sparked great
interest, which in turn have created an indirect interest on what effect, if any, the environ-
mental 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 at OU-3 and the
selected remedy identified in the ROD. An ad 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 selected remedy for cleanup of OU-3 was also placed in
the information repository and distributed at the public meeting. The ad 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. A news release was distributed to
the media listed in the community relations plan.
KN/31S7/WP3187.11/01-22-96(lfc05ain)/DO/El 11-1
-------
11.3 Summary of Comments Received During the Public Comment Period and
Air Force Responses
The public comment period on the proposed plan for cleanup of the groundwater and soils at
OU-3 was held from June 25 through July 26, 1995. No written comments were received.
11.4 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 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 JJRP at Williams AFB. The RAB,
whose expanded membership includes representatives of the USAF, State 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.
Nine 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 environmental investigation. Three others described the proposed plans for
cleanup of OU-1, OU-2, and OU-3.
A 35-millimeter slide presentation describing the IRP has been 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.
KN/3187/WP31S7.11A)l-22-96(l(M)5am)/DO/El 11-2
-------
News releases and public notices have been submitted to the local papers announcing
milestones in the IRP. Topics include:
Signing of the FFA
Availability for comment on engineering evaluation/cost analyses for the Radio-
active Instrumentation Burial Area, the Fire Protection Training Area 1, and the
Pesticide Burial Area
Availability of the OU-1, -2 and -3 RI reports for review
Availability of the OU-1, -2, and -3 proposed plans for public comment
Announcement of public meeting to present the Proposed Plan for OU-1, -2, and
-3.
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 -2.
The Tribune carried notices for the public comment period for the OU-3 proposed plan.
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. 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 of the four meetings for review. Press packets,
including the handouts, hard copies of slides, and the news releases, were available for media
representatives who attended the meeting.
KN/31S7/WP3187.11/01-Z2-96(l<«)5iin)/DO/El 11-3
-------
-------
12.0 References
AeroVironment, Inc. (AV), 1987, Installation Restoration Program, Phase II Confirma-
tion/Quantification, Stage 2 Report, Williams AFB, AeroVironment Report AV-FR-87/536.
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.
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.
Halliburton NUS Corporation (HNUS), 1994, Site Activity Report, Removal of Fire Training
Area Structures, Site FT-02, prepared for Air Force Base Conversion Agency, Williams Air
Force Base, Arizona, September 1993.
IT Corporation, 1995, Final Feasibility Study Report, Operable Unit 3, prepared for Air
Force Base Conversion Agency, Williams Air Force Base, Arizona, by IT Corporation, May
1995.
IT Corporation, 1994, Final Remedial Investigation Report, Operable Unit 3, prepared for
Air Force Base Conversion Agency, Williams Air Force Base, Arizona, by IT Corporation,
September 1994.
IT Corporation, 1993a, Final Engineering Evaluation/Cost Assessment, Fire Protection
Training Area No. 2, prepared for the USAF Air Training Command, Randolph Air Force
Base, Texas, October 1993.
IT Corporation, 1993b, Final Work Plan Addendum, Operable Unit 3, prepared for the
USAF Air Training Command, Randolph Air Force Base, Texas, August 1993.
IT Corporation, 1993c, Field Sampling Plan Addendum, Operable Unit 3, prepared for the
USAF Air Training Command, Randolph Air Force Base, Texas, August 1993.
IT Corporation, 1993d, Final Baseline Ecological Risk Assessment Report, Operable Unit 3
- Basewide, prepared for Air Force Base Conversion Agency, Williams Air Force Base,
Arizona, by FT Corporation, December 1993.
IT Corporation, 1992, Final Remedial Investigation Report, Operable Unit 1, prepared for
the USAF Air Training Command, Randolph Air Force Base, Texas, October 1992.
KN/3187/WP31S7.12/01-22-96(l(H)5am)/DO/El 12-1
-------
IT Corporation, 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, 199Ib, Williams Air Force Base Final Field Sampling Plan, prepared for
the USAF Air Training Command, Randolph Air Force Base, Texas, April 1991.
IT Corporation, 1991c, Williams Air Force Base Final Community Relations Plan, prepared
for the USAF Air Training Command, Randolph AFB, Texas, by IT Corporation.
IT Corporation, 1990, Final Decision Document, Southwest Drainage System (OT-01),
Williams Air Force Base, prepared for the USAF Air Training Command, Randolph Air
Force Base, Texas, September 1990.
IT Corporation, 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, 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.
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. Mortvedt (ed.).
Micronutrients in Agriculture, Soil Sci. Soc. Amer. Book Series No. 4, Soil Sci Soc. Amer.,
Inc., Madison, Wisconsin.
Sauerback, D., 1988, "Transfer of Heavy Metals in Plants," Technical Report No. 40, Hazard
Assessment of Chemical Contaminants in Soil, August 1990, European Chemical Industry
Ecology and Toxicology Centre, Brussels, Belgium, ISSN-0773-8072-40.
Sunregion Associates, 1987, Maricopa Land Use Plan, Ocean Creek and East Mesa,
Subarea A2.
U.S. Department of Energy (DOE), 1989, A Manual for Implementing Residual Radioactive
Material Guidelines, ANL/ES-160, DOE/CH/8901, Argonne National Laboratory, Argonne,
Illinois.
KN/3187/WP3187.12«>l-22-96(lft05«n)/DO/El 12-2
-------
U.S. Department of Housing and Urban Development, 1979, Firm Flood Insurance Rate
Map, Maricopa County, Arizona, Unincorporated Areas: Community, Panel No. 040037
1600A.
U.S. Environmental Protection Agency (EPA), 1994a, IRIS (Integrated Risk Information
System), On line, Environmental Criteria and Assessment Office, Cincinnati, Ohio.
U.S. Environmental Protection Agency (EPA), 1994b, Region IX Preliminary Remediation
Goals (PRGs) First Half 1994, EPA Region IX, San Francisco, CA, February 1, 1994.
U.S. Environmental Protection Agency (EPA), 1994c, Guidance Manual for the Integrated
Exposure Uptake Bioldnetic Model for Lead in Children, Office of Emergency and Remedi-
al Response, Publ. No. 9285-7-15-1, EPA/540/R-93/081, NTIS No. PB93-963510.
U.S. Environmental Protection Agency (EPA), 1994d, Revised Interim Soil Lead Guidance
for CERCLA Sites and RCRA Corrective Action Facilities, Office of Solid Waste and
Emergency Response (OSWER) Directive 9355.4-12, EPA/540/F-94/043.
U.S. Environmental Protection Agency (EPA), 1993, Health Effects Assessment Summary
Tables, Annual Update, FY1993, Including Supplement No. 1, July 1993, OHEA ECAO-
CIN-909, March 1993.
U.S. Environmental Protection Agency (EPA), 1992, Dermal Exposure Assessment:
Principles and Applications, Interim Report, Office of Research and Development, Washing-
ton, D.C., EPA/600/8-91/001B, including Supplemental Guidance, dated August 18, 1992.
U.S. Environmental Protection Agency (EPA), 1991a, Risk Assessment Guidance for
Superfund, Volume I: Human Health Evaluation Manual, Supplemental Guidance,
Standard Default Exposure Factors, Interim Final, EPA, Office of Emergency and Remedial
Response, Washington, DC.
U.S. Environmental Protection Agency (EPA), 1991b, Risk Assessment Guidance for
Superfund, Volume I: Human Health Evaluation Manual (Part B, Development of Risk-
Based Preliminary Remediation Goals), Interim, Office of Emergency and Remedial
Response, Washington, DC, Publication 9285.7-01B.
U.S. Environmental Protection Agency (EPA), 1990a, 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, D.C.
U.S. Environmental Protection Agency (EPA), 1990b, Technical Support Document for
Lead, Prepared by Syracuse Research Corporation under contract to the Environmental
Criteria and Assessment Office, Cincinnati, Ohio.
KN/3187/WP3187.12/01-22-96(l(h05am)/DO/El 12-3
-------
U.S. Environmental Protection Agency (EPA), 1989a, 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), 1989b, Risk Assessment Guidance for
Superfund, Human Health Risk Assessment: U.S. EPA Region IX Recommendations
(Interim Final).
U.S. Environmental Protection Agency (EPA), 1987, "National Primary Drinking Water
Regulations, Synthetic Organic Chemicals; Monitoring for Unregulated Contaminants,"
Federal Register 52:25690-25734.
KN/3187/WP3187.12/01-22-9«
-------
APPENDIX A
DETERMINATION OF CHEMICALS OF CONCERN, CLEANUP LEVELS,
AND REMEDIAL ACTION OBJECTIVES FOR OU-3
SOIL AND GROUNDWATER
KN/3187/WP3187 JVPP/01 -22-96(938am)/D(VEl
-------
-------
Table A-1
Determination of Chemicals of Concern (COC) and Cleanup Levels in Soil
Fire Protection Training Area No. 2 (FT-02), OU-3
Williams Air Force Base
Chemicals of Potential Concern
Value or Range
of Detection
Limits
(mg/kg)
~ Value or Range
of Detected
Concentrations
(mg/kg)
PRG
(mg/kg)
UCL
Concentration81
(mg/kg)
COC
Decision Basis
Organics
1 ,2-Dichlorobenzene
1 ,4*Dichterober*zen©i>
Acetone
Benzene*5 .
Bis(2-ethylhexyl)phthalate
Chloroform**
Ethyl benzene
Methyl ethyl ketone
Methylene chloride
Toluene
Xylenes
0.36 to 1
0,36 fcl
0.011 to 0.012
G.OOShJg
0.36 to 0.39
0,005 tot
0.005 to 1
0.011 to 10
0.005 to 1
0.005 to 2
0.005 to 2
3 to 23
2 to 120
0.01 2 to 0.029
\ 2 to 310
0.078 to 2.3
tta2
1 to 170
13 to 1400
0.075 to 11
3 to 260
2 to 640
2,300
j JrV* ' |
2,000
iA«
32
1 &53F 1
2,900
8,700
11
1,900
980
4
«*
0.017
J£
1.4
«B6
6.6
112
3
9.4
27
No
Ye$
No
; Yfcs
No
Yes
No
No
No
No
No
UCL below PRG
Requires action
to *neet PRG
UCL below PRG
Requires, action
to meet PRG
UCL below PRG
: Requires action
to meet PRG
UCL below PRG
UCL below PRG
UCL below PRG
UCL below PRG
UCL below PRG
Inorganic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Zinc
2
3
6to7
0.7 to 10
0.3
9 to 10
5
1 to5
4 to 24
13 to 44
4.0 to 70
5.9
13 to 28
33 to 100
38
210
2,800
400
23
1,500
23.000
4.6
16
20
18
7
18
62
No
No
No
No
No
No
No
UCL below PRG
UCL below PRG
UCL below PRG
UCL below PRG
UCL below PRG
UCL below PRG
UCL below PRG
aUCL Concentration is calculated for data collected from surface to 25 feet bgs.
bChemical of concern for FT-02 soil.
°CIeanup level.
KN/3187/WP3187 .APP/01 -22-96{9:38am)/DQ/El
-------
Table A-2
Determination of Chemicals of Concern (COC) and Cleanup Levels in Groundwater
Fire Protection Training Area No. 2 (FT-02), OU-3
Williams Air Force Base
Chemicals of Potential
Concern
Value or Range
of Detection
Limits (ug/L)
Range of
Detected
Concentrations
(ug/L)
Base-Specific8
Background
Range or
Value
(ng/L)
PRG
(ug/L)
UCL
(ug/L)
Decision Basis
COC
Organlcs
Acetone
Carbon Disulfide
Methylene Chloride
10
5
0.5 to 15
2.0 to 4.0
1.0 to 6.0
0.7 to 6.0
NAb
NA
NA
610
21
5
4.3
6.4
2.9
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
No
No
No
Inorganics
Lead
Zinc
1 to 5
20
6.0 to 2 1.0
340.0 to 3800.0
ND°
ND to 13.3d
15
5,000
6.5
2,500
UCL concentration below PRG
UCL concentration below PRG
No
No
aWells used to establish a Base-specific range: SS01-W-10, SS01-W-17, SS01-W-26, SS01-W-27, LF01-W-12 (September 1993 sampling).
bNA - Not available.
CND - Not detected.
dAnalyte concentration is between instrument detection limit (IDL) and contract-required detection limit (CRDL).
KN/3187/WP3187.APP/01-22-96(9:38am)/DO/E1
-------
Table A-3
Determination of Chemicals of Concern (COC) and Cleanup Levels in Soil
Southwest Drainage System (SD-09), OU-3
Williams Air Force Base
(Page 1 of 2)
Chemicals of
Potential Concern
Value or Range
of Detection Limits
(mg/kg)
Value or Range
of Detected
Concentrations
(mg/kg)
PRG
(mg/kg)
UCL
Concentration3
(mg/kg)
COC
Decision Basis
Organlcs
Acetone
Bis(2-ethylhexyl)phthalate
Di-n-butyl phthalate
Diethyl phthalate
Ethyl alcohol
Methylene chloride
Phenol
Pyrene
Toluene
1,1,1-Trichloroethane
0.010 to 0.025
0.330 to 1.700
0.33 to 1.7
0.33 to 1.7
0.05 to 0.05
0.005 to 0.013
0.3310 1.7
0.33 to 1.7
0.005 to 0.013
0.005 to 0.013
0.002 to 0.21
0.02 to 18
0.02 to 0.4
0.019 to 0.41
0.051 to 0.11
0.007 to 0.13
0.22to 1.1
0.024 to 0.41
0.001 to 0.012
0.002 to 0.012
2,000
32
6,500
52,000
NLb
11
39,000
2,000
1,900
3,200
0.018
3.6
0.25
0.25
0.036
0.016
0.29
0.27
0.004
0.004
No
No
No
No
No
No
No
No
No
No
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
Low UCL. No PRG available
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
Inorganics
Antimony
Arsenic
Beryllium
Cadmium
12 to 20
2 to 5
1 to 3
0.2 to 3
8.5 to 68
0.46 to 5.7
0.47 to 2.2
0.6 to 90
31
4.3
1.6
38
22
2.4
0.90
5.1
No
No
No
No
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
KN/3187/WP3187.APP/01-22-96(9:38am)/DO/E1
-------
Table A-3
Determination of Chemicals of Concern (COC) and Cleanup Levels in Soil
Southwest Drainage System (SD-09), OU-3
Williams Air Force Base
(Page 2 of 2)
Chemicals of
Potential Concern
Chromium
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
Value or Range
of Detection Limits
(mg/kg)
2 to 5
0.4 to 6
0.6 to 2
0.2 to 0.4
8 to 8
1 to 3
2 to 5
2 to 30
4 to 4
Value or Range
of Detected
Concentrations
(mg/kg)
12to53
0.4 to 61
8 to 96
0.1 7 to 0.1 9
9 to 31 .5
0.47 to 0.58
1.1 to 13
0.44 to 0.95
28 to 278
PRO
(mg/kg)
210
2,800
400
23
1,500
380
380
4.9
23,000
UCL
Concentration3
(mg/kg)
33
24
32
0.11
20
0.64
1.8
2.8
93
COC
No
No
No
No
No
No
No
No
No
Decision Basis
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
UCL concentration below PRG
aUCL concentrations calculated from combination surface and subsurface soils.
bNL = Not listed.
KN/3187/WP3187.APP/01 -22-96(9:38am)/DO/E 1
-------
Table A-4
Summary of Remedial Action Objectives, OU-3
Williams Air Force Base
Site
Remedial Action Objective
FT-02
Soil
Protect human health and the environment by reducing the concentration of
benzene, chloroform, and 1,4-dichlorobenzene in FT-02 soils to 1.4, 0.53, and
7.4 milligrams per kilogram (mg/kg), respectively. The residual total ILCR for
all chemicals in soil summed across all exposure pathways will be within the
acceptable risk range of 10"6 to 10"4. The reduction in organic contaminants
will prevent the potential future migration of contaminants to groundwater.
Groundwater
No RAOs were developed for groundwater because the UCL concentration of
all COPCs are below PRGs.
SD-09
Soil
No RAOs were developed for the soil because the UCL concentrations of all
COPCs are below PRGs.
Groundwater
There is no indication of groundwater contamination at SD-09; therefore, no
RAOs were developed.
KN/3187/WP3187 APP/01 -22-96(9:38am)/DQ/El
-------
-------
APPENDIX B
COST TABLES FOR FIRE PROTECTION TRAINING AREA
NO. 2 (FT-02) REMEDIAL ALTERNATIVES
KN/3187/WP3187.APP/01-22-96(9:38am)/D
-------
-------
TABLE B-l. NO ACTION FOR FT-02 SOILS
Annual Operation and Maintenance Costs
Williams AFB
Project-409877.010
KT - S8 - 03/29/95
COST COMPONENT
1. Monitoring labor
(for groundwater sampling,
1 sample at Western Pit,
3 samples at Eastern Pit,
2. Purchased services
Groundwater Monitoring (VOC)
1 sampling event per year,
1 sample at Western Pit,
3 samples at Eastern Pit,
3. Data evaluation/reporting
UNIT COST ($)
50
600
100
UNIT
hour (hr)
sample
hr
QTY UNITS/ PERIOD
32 hr per year
4 samples/event
32 hr/year
ANNUAL
COST ($)
1,600
2,400
3,200
TOTAL OPERATING COST 7,200
1. Insurance, permits, taxes
2. Rehabilitation costs
3. Contingency
4. Periodic site review (a)
4% operating
25% operating
300
NA
1,800
28,000
TOTAL ANNUAL OPERATING COST (-f50%, -30%) 37,300
a. Every 5 years, including groundwater modeling, cost shown is allocation for one year.
NA-not applicable
-------
TABLE B-2. SVE FOR FT- 02 SOILS
Initial Capital Costs
Williams AFB
Project-409877.010
KT-S6FTSV-03/29/95
COST COMPONENT
DESCRIPTION
COST ($)
DIRECT CAPITAL COSTS
1. Site Preparation
2. Extraction Wells
- Western Pit
- Eastern Pit
3 . Demobilization of operating wells
4. Nested pieziometers (PZ)
5. Piping system and foundation
(including surface sealing)
6. SVE Vacuum Skid-Mounted Systems
- Western Pit: One 40 scfin blower
- Eastern Pit: One 600 scfin blowers
7. Condensate transfer system (collected
in two 500 gal tanks on a trailer)
8. One Thermal Oxidation System with
catalytic module (no heat exchanger)
9. Electrical equipment
10. Shipping
3 acres
All wells are 4" diameter
1 well at 10 ft deep, 10 ft screen
3 wells at 86 ft deep, and 5 wells at
43 ft deep, each has 43 ft screen
After completion of the operation (9 wells)
2 piezometers at 86 ft, 1 PZ at 10 ft
Extraction well nearby can be used also
800 linear feet (4", 6 "and 10" diameter)
(underground construction cost is included)
Including air/water separator & instrumentation
10" Hg vacuum, 5 Hp motor
18" Hg vacuum, 125 Hp motor
Condensate from air/water separator will
be transported to the existing system
Skid mounted system, rated for 1,000 scfin
3 million (MM) BTU/hour, 1,400 deg F
Including installation, wiring, and
telemanager monitoring system
8% of hems 6 and item 8 (approx)
TOTAL DIRECT COSTS (TDC)
10,000
2,000
47,000
8,000
15,000
59,000
22,000
93,000
10,000
103,000
32,000
17,400
418,400
INDIRECT CAPITAL COSTS
1 . Engineering and related tech support
2. SVE Pilot Test
3. License, Permit, and Legal Fees
4. Start-up (sampling costs are included)
5. Contingency
20% TDC
Air permeability and pressure test
(well installation is not included)
2% TDC
25 % TDC
83,700
72,000
8,400
65,000
104,600
TOTAL INSTALLED COST (+50%, -30%) 752,100
NA - not applicable
-------
TABLE B-3. SVE FOR FT- 02 SOILS
Annual Operation and Maintenance Costs
Williams AFB
Project-409877.010
KT-S6FTSV- 03/29/95
COST COMPONENT
1. Operating labor (a)
2. Monitoring labor
3. Maintenance
4. Materials
5. Utilities
. Electric Power
2 Vacuum skids (125+5 Hp),
gas fens, and water pumps.
. Fuel for fume incineration.
6. Disposal
7. Purchased services:
a) Vapor samples analyses (b)
b) Water samples analyses
c) Soil Boring (b) (c)
d) Soil Monitoring (VOC)
(d)
8. Data evaluation
UNIT COST (S)
50
50
0.08
5.00
400
350
15,000
2,500
100
UNIT
hour (hr)
hour (hr)
Kwhr
MMBTU
sample
sample
sampling
event
sampling
event
hr
QTY UNITS/ PERIOD
8 hours per week
8 hours per month
2,775 Kwhr/day
16.8 million BTU/day
4 samples/month
2 samples/month
3 borings/2 years
1 sampling event
per 2 years
40 hr/3 months
ANNUAL
COST (S)
20,800
4,800
10,000
NA
81,000
30,700
NA
19,200
8,400
7,500
1,250
16,000
TOTAL OPERATING COST 199,650
1. Insurance, permits, taxes
2. Rehabilitation costs
3. Periodic site review (e)
4. Contingency
4% operating
25% operating
8,000
NA
NA
49,900
TOTAL ANNUAL OPERATING COST (+50%, -30%) 257,550
a. Operator is required to check system once per week (at 8 hours/trip)
b. Start-up sampling costs are not included.
c. 3 Borings with split spoon sampling.
d. Soil analysis includes a total of 5 samples.
e. Every 5 year; cost shown is allocation for one year.
NA-not applicable
-------
TABLE B-4. BIOVENTEVG FOR FT- 02 SOILS
Initial Capital Costs
Williams AFB
Project-409877.010
KT - S7FTBIO - 03/29/95
COST COMPONENT
DESCRIPTION
COST (S)
DIRECT CAPITAL COSTS
1. Site Preparation
2. Extraction Wells
- Western Pit
- Eastern Pit
3 . Demobilization of operating wells
4. Nested pieziometers (PZ)
5 . Piping system and foundation
(surface sealing is not included)
6. Bio-Air Injection Skid-Mounted Systems
- Combined Western Pit and
Eastern Pit
7. Condensate transfer system
8. Electrical equipment
9. Shipping
3 acres
All wells are 4" diameter
1 wells at 10 ft deep, 10 ft screen
3 wells at 86 ft deep, and 5 wells at
43 ft deep, each has 43 ft screen
After completion of the operation (9 wells)
2 piezometers at 86 ft, 1 PZ at 10 ft
Extraction well nearby can be used also
800 linear feet (4", 6 "and 10" diameter)
(underground construction cost is included)
One 200 scfin blower,
lOpsig, 20 Hp motor
Condensate from 1 air/water separator
will be pumped to the existing system
Including installation, wiring, and
telemanager monitoring system
Approximate
TOTAL DIRECT COSTS (TDQ
10,000
2,000
47,000
8,000
15,000
49,000
30,000
NA
20,000
4,000
185,000
INDIRECT CAPITAL COSTS
1 . Engineering and related tech support
2. SVE Pilot Test
3. Bioassessment, bio treatability test
4. License, Permit, and Legal Fees
5. Start-up (sampling costs are included)
6. Contingency
Air permeability and pressure test
(well installation is not included)
Insitu pilot bio treatability test
2%TDC
25%TDC
75,000
72,000
175,000
3,700
65,000
46,300
TOTAL INSTALLED COST (450%, -30%) 622,000
NA - not applicable
NI - not included
-------
TABLE B-5. BIOVENTING FOR FT- 02 SOILS
Annual Operation and Maintenance Costs
Williams AFB
Project-409877.010
KT - S7FTBIO - 03/29/95
COST COMPONENT
1. Operating labor (a)
2. Monitoring labor
3. Maintenance
4. Materials
5. Utilities
. Electric Power
1 Blower skid (20 Hp),
6. Disposal
7. Purchased services:
a) Vapor samples analyses (b)
b) Water samples analyses
c) Soil Boring (b) (c)
1 sampling event / 2 years
d) Soil Monitoring (VOC)
(d)
e) Soil Bio Monitoring
(3 bores, 5 samples)
8. Data evaluation
UNIT COST ($)
50
50
0.08
400
350
15,000
2,500
6,000
100
UNIT
hour (hr)
hour (hr)
Kwhr
sample
sample
sampling
event
sampling
event
sampling
event
hr
QTY UNITS/ PERIOD
8 hours per week
8 hours per month
358 Kwhr/day
4 samples/month
1 samples/month
3 borings/2 years
1 sampling event
per 2 years
1 sampling event
per 2 years
40 hr/3 months
ANNUAL
COST ($)
20,800
4,800
10,000
NA
10,500
NA
19,200
4,200
7,500
1,250
3,000
16,000
TOTAL OPERATING COST 97,250
1. Insurance, permits, taxes
2. Rehabilitation costs
3. Periodic site review (e)
4. Contingency
4% operating
25% operating
3,900
NA
NA
24,300
TOTAL ANNUAL OPERATING COST (450%, -30%) 125,450
a. Operator is required to check system once per week (at 8 hours/trip)
b. Start-up sampling costs are not included.
c. 3 Borings with split spoon sampling.
d. Soil analysis includes a total of 5 samples.
e. Every 5 year; cost shown is allocation for one year.
NA - not applicable
-------
-------
APPENDIX C
LOCATION-SPECIFIC AND ACTION-SPECIFIC
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
KN/3187/WP3187.APP/01 -22-96(938am)/D(VE1
-------
I
-------
Table C-1
Chemical-Specific Applicable or Relevant and Appropriate Requirements
Fire Protection Training Area No. 2 (FT-02), OU-3
Williams Air Force Base
Chemical of Concern
Benzene
Chloroform
1 ,4-Dichlorobenzene
UCL Concentration
(mg/kg)
7.3
0.66
8.2
Cleanup Level
(mg/kg)
1.4
0.53
7.4
Arizona HBGLa
(mg/kg)
47
220
57
Ab
RARC
FT02-4
FT02-5
FT02-4
FT02-5
FT02-4
FT02-5
aJune 1996, Arizona Health Based Guidance Levels (HBGLs) were adopted by ADEQ on December 15, 1995, through emergency rule, as soil cleanup
standards. These cleanup standards are undergoing final review prior to certification by the Arizona Attorney General. Once promulgated, the standards
will become applicable or relevant and appropriate requirements (ARARs).
bCriteria is applicable for alternatives listed.
°Criteria is relevant and appropriate for alternatives listed.
KN/3187/WP3187.APP/05-03-96(8:38am)/F1 /E1
-------
Table C-2
Location-Specific Applicable or Relevant and Appropriate Requirements
Fire Protection Training Area No. 2 (FT-02), OU-3
Williams Air Force Base
Location
Within area where action
may cause irreparable
harm, loss, or destruction
of significant artifacts
Requirement(s)
Action to recover and preserve
artifacts
Prerequisite(s)
Alteration of terrain that
threatens significant scientific,
prehistoric, historic, or
archaeological data
Citation
National Archaeological
and Historical Preservation
Act (16 USC Section 469);
36 CFR Part 65
Comments
Aa
RARb
FT02-4
FT02-5
"Criteria is applicable for alternatives listed.
bCriteria is relevant and appropriate for alternatives listed:
Alternative FT02-1: No Action
Alternative FT02-4: Soil Vapor Extraction
Alternative FT02-5: Bioventing.
KN/3187/WP3187.APP/05-03-96(8:39am)/F1/E1
-------
Table C-3
Action-Specific Applicable or Relevant and Appropriate Requirements
Fire Protection Training Area No. 2 (FT-02), OU-3
Williams Air Force Base
(Page 1 of 2)
Action
Requirement(s)
Prerequisite(s)
Citation
Comments
RARb
Air Emissions
Control During
Remediation
Control of air emissions of volatile organics,
particulates, and gaseous contaminants.
Emission of VOCs.
particulates, and
gaseous air
contaminants
Maricopa County Air
Quality Standards (Rules
200,210.220,320)as
dictated by the Clean Air
Act
FT02-4
FT02-5
Surface Water
Control
Prevent run-on and control and collect runoff from a
24-hour 25-year storm (land treatment facility).
RCRA hazardous waste
treated, stored, or
disposed after the
effective date of the
requirements.
R18-8-264 referencing:
40 CFR 264.273 (c) (d)
FT02-4
FT02-5
Container
Storage
(On Site)
Containers of hazardous waste must be:
Maintained in good condition
Compatible with hazardous waste to be stored
Closed during storage (except to add or remove
waste).
Inspect container storage areas weekly for
deterioration.
Place containers which contain free liquid on sloped,
crack-free base, and protect from contact with
accumulated liquid. Provide containment system
with a capacity of 10 percent of the volume of
containers of free liquids or the volume of the largest
container, whichever is greater.
RCRA hazardous waste
(listed or characteristic)
held for a temporary
period before treatment,
disposal, or storage
elsewhere (40 CFR
264.10) in a container
(i.e., any portable
device in which a
material is stored,
transported, disposed
of, or handled).
R18-8-264 referencing:
40 CFR 264.171
40 CFR 264.172
40 CFR 264.173
40 CFR 264.174
40 CFR 264.175
These requirements are
applicable for any
contaminated soil,
groundwater, or treatment
system waste that might
be containerized and
stored on site prior to
treatment or final
disposal. Groundwater or
soil containing a listed
waste must be managed
as if it were a hazardous
waste so long as it
contains a constituent of
the listed waste.
FT02-4
FT02-5
KN\3187WP3187.C-3ND5-03-96(3:03pm)
DChNE
-------
Table C-3
Action-Specific Applicable or Relevant and Appropriate Requirements
Fire Protection Training Area No. 2 (FT-02), OU-3
Williams Air Force Base
(Page 2 of 2)
Action
Container
Storage
(On Site)
(Continued)
Pretreatment
for Discharge
toPOTW
Requirement(s)
Remove spilled or leaked waste in a timely manner
to prevent overflow of the containment system.
Keep containers of ignitable or reactive waste at
least 50 feet from the facility's property line.
Keep incompatible materials separate. Separate
incompatible materials stored near each other by a
dike or other barrier.
At closure, remove all hazardous waste and residues
from the containment system, and decontaminate or
remove all containers and liners.
Storage of banned wastes must be in accordance
with 40 CFR 268. When such storage occurs
beyond 1 year, the owner/operator bears the burden
of proving that such storage is solely for the purpose
of accumulating sufficient quantities to allow for
proper recovery, treatment, and disposal.
Establish agreement with POTW with regards to
pretreatment effluent discharge limits for treated
water.
Prerequisite(s)
Discharge of treated
water to POTW
Citation
R1 8-8-264 referencing:
40 CFR 264.1 75
40 CFR 264. 176
40 CFR 264.1 77
40 CFR 264. 178
R1 8-8-268 referencing:
40 CFR 268.50
40 CFR 403
Comments
Need to establish with
POTW prior to discharge.
A*
FT02-4
FT02-5
FT02-4
RAR"
"Criteria is applicable for alternatives listed.
bCriteria is relevant and appropriate for alternatives listed.
Alternative FT02-1: No Action
Alternative FT02-4: Soil Vapor Extraction
Alternative FT02-5: Bioventing.
KN\3187WP3187.C-3V>5-03-96(3:03pm)
DO\NE
-------
-------
------- |