United States
Environmental Protec: .1
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R09-87/012
September 1987
SEPA
Super jnd
Enforc ?ment Decision Document:
Litchfii Id Airport/Phoenix, AZ
-------
TECHNICAL REPORT DATA
'rteau 'rtatt Inttmtnom on tut rtvtnt btfort
EPA/ROD/R09-87/012
3 Reo"€Nr s Access.CN so
4. TITH ANOSUITITUI
SUPERFUND RECORD OF"DECISION
Litchfield, AZ
Ficst Remedial Action
7 AUTMORIS)
OATI ;'
September 29, 1987
« MR0ORMING ORGANIZATION COOi
• »f R0ORM1NG ORGANIZATION
NO
». MR'ORMINO ORGANIZATION NAMI AND AOORISS
10. PROGRAM
NO
11 CONTRACT/GRANT NO
12. SPONSORING AOiNCV NAM* AND AOOACSS
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. TVM O' RMORT ANQ MRlOO C0v6»eo
Final ROD Report
14, SPONSORING AQINCV CQOf
800/00
19. SU^^LIMINTAAY NOTIS
14. AUTRACT
The Litchfield/Phoenix-Goodyear Airport (PGA) site covers a total area of
approximately 35 square miles and is located approximately 17 miles west of Phoenix,
Arizona. The site is divided into a northern and a southern area by a ground water.
divide running under the Yuma Road area. Section 16 (approximately 17 acres) lies in
the southern area and includes the Loral Corporation facility (formerly owned by
Goodyear Aerospace Corporation) and the Phoenix-Goodyear Airport (formerly owned by U.S.
Navy), both being potential sources of VOC contamination. Ground water contaminant
concentrations in Section 16 are at least 100 times greater than down gradient levels.
Development by the City of Goodyear is planned for the area west, or downgradient, of
Section 16. This development will include using the ground water resources currently
threatened by contamination in Section 16. In 1981, the Arizona Department of Health
Services discovered solvent and chromium contamination in the ground water within the
PGA area. Additional sampling in 1982 and 1983 found 18 wells contaminated with TCE.
The primary contaminants of concern include: TCE, VOCs and chromium.
The selected interim remedial action for this site includes: ground water pump and
treatment from the Subunit A aquifer of the entire Section 16 area by air stripping with
reinjection of the stripped water back into the Subunit A aquifer; and Loral Corporation
(See Attached Sheet)
17.
KIV WOMOC AMO OOCUMflNT AMAl*SIS
oucftirroMS
b.lOINTI»ltM/OMN INOIO r(MM« C. COS-ATI F*!d/G«*jp
Record of Decision
Litchfield, AZ
First Remedial Action
Contaminated Media: gw
Key contaminants: VOCs, TCE, chromium
DISTRIBUTION STATIMINT
19. SECURITY CLASS ' nut Atpo'tl
None
21 NO o
57
20. StCuRiTY CLASS .nut pi ft i
IP*
1214-1 (*•»• 4-77) •n«yieu» IOITIQM .» O*«OW>T«
-------
EPA/ROD/R09-87/012
Litchfield, AZ
First Remedial Action
16. ABSTRACT (continued)
and PGA will continue to pump ground water from Subunit B/C and treat with granular
actived carbon. The estimated present worth cost for this selected remedy is $2,358,500
with O&M of $800,200.
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DECLARATION FOR THE RECORD OF DECISION
SITE
Phoenix-Goodyear Airport (PGA) site, Section 16 Operable
Unit, Goodyear, Arizona.
PURPOSE
This decision document represents the selected remedial action
for the Section 16 Operable Unit at the PGA Superfund site
(see Figure 1). This operable unit addresses groundwater
contamination in the upper alluvial unit only in Section 16.
Groundwater contamination beyond Section 16, as well as soil
contamination, will be addressed in the final remedial
action. This remedial action was developed in accordance
with CERCLA, as amended by SARA, and the National Con-
tingency Plan. The Arizona Department of Environmental
Quality and Arizona Department of Water Resources have
agreed to the selected remedy.
BASIS
This decision is based on the administrative record for the
P<~\ site, which includes the Phase I Remedial Investigation
a..d the Section 16 Operable Unit Feasibility Study. The
attached index (Appendix A) identifies the items contained
in the administrative record upon which the selection of the
remedial action is based.
DESCRIPTION
The PGA site is located approximately 17 miles to the west
of Phoenix, Arizona. The site is divided into a northern
and a southern area by a groundwater divide running under
the Yuma Road area. Section 16 lies in the southern area
and includes the Loral Corporation facility (formerly owned
by Goodyear Aerospace Corporation) and the Phoenix-Goodyear
Airport (formerly owned by U.S. Navy), both being potential
sources of volatile organic compound (VOC) contamination.
Groundwater contaminant concentrations in Section 16 are at
least 100 times greater than those of downgradient levels.
Development by the City of Goodyear is planned for the area
west, or downgradient, of Section 16. This development will
include using the groundwater resources currently threatened
by contamination in Section 16. As a result, the Section 16
Operable Unit was designed to address these high levels of
groundwater contamination. An operable unit is a remedial
action that is separated from the overall site cleanup
RD/R52/021
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actions when it can be done expeditiously, is cost-effective,
prevents contaminant migration, and is consistent with the
final site remedy.
To meet these objectives., the following remedial action has
been chosen. The chosen alternative segregates the water in
the upper alluvial unit into Subunit A, which is presently
unsuitable for drinking water due to its high dissolved
solids content, from the aquifers in Subunit B/C, which is a
potential drinking water source. (Subunits B and C have been
combined as Subunit B/C because, in this area, they are
hydraulically connected.) The rationale for this operable
unit is that it will stop contamination within Subunit A
from spreading laterally, and it will prevent contamination
from Subunit A to enter Subunit B/C via the casing of exist-
ing wells in the area. Subunit B/C is planned for future
use of the City of Goodyear in areas directly downgradient
of the site. For Subunit A, until levels of contaminants
are reduced to meet Applicable or Relevant and Appropriate
Requirements (ARARs), water will be pumped from the entire
Section 16 area, and air stripping will be used to reduce
VOC contamination to meet federal and state standards for
drinking water (see Table 1). The air stripping towers will
be equipped with air emission controls in order to meet
county requirements that all new air emission sources employ
reasonably achievable control technology to reduce emissions,
and as promulgated by the Superfund Amendment and Reauthori-
zation Act (SARA), remedies should significantly and perma-
-/ nently reduce the volume, toxieity, and mobility of the
contaminants.
At this time, aquifers in Subunit B/C are being pumped by
Loral Corporation for industrial and drinking water purposes
and by the Phoenix-Goodyear Airport for domestic supply.
All water used for drinking is sent to a carbon adsorption
system for treatment. This pumping system is helping to
contain contaminant migration in a manner that is acceptable
for this interim period until the final remedy is chosen.
In addition, clusters of newly installed deep monitoring
wells to the west of the airport will monitor Subunit B/C
and detect any contaminant migration away from the source
area. Therefore, no expedited remedial action is planned
for Subunit B/C at this time. Pumping schedules for Loral
Corporation and the airport will be designed to optimize
production needs with control of the contaminant plume.
The level of treatment will be in accordance with federal
and state standards. Treated water from the Subunit A aqui-
fer will be reinjected into that same aquifer to minimize
the environmental impact of additional groundwater withdrawal,
RD/R52/021
-------
Table 1
STATE AND FEDERAL
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS*
(concentrations in ppb)
AND OTHER CRITERIA
Compound
Trichloroethylene
1,1,1-Trichloroethane
1,1-Dichloroethylene
Perchloroethylene
Trans-1,2-dichloroethylene
Carbon tetrachloride
Chloroform
Chromium
Arsenic
AWQC ADHS
SDWA SDWA Proposed Proposed Drinking Water Action Treatment Plant
MCL MCLG MCL MCLG Only Level Discharge Level
5
200
7
50
SO
0
200
7
0
70
0
120
50
5
200
1
3
0.5
5
200
7
3
70
5
0.5
50
Clean Water Act requirements will be determined during NPDES review.
Source is not a byproduct of municipal water supply chlorination.
NOTES: ADHS—Arizona Department of Health Services
AWQC—Ambient Water Quality Criteria
MCL Maximum Contaminant Level
MCLG—Maximum Contaminant Level Goal
SDWA—Safe Drinking Water Act
DW—Drinking Water
Sources: U.S. EPA 1986. Public Health Assessment Manual
ADHS 1987. S. Eberhart
RD/R56/057-4
-------
DECLARATION
The selected remedy for this operable unit is protective of
human health and the environment, meets federal and state
requirements that are applicable or relevant and appropri-
ate, and is cost-effective. This remedy satisfies the pref-
erence for treatment that reduces toxicity, mobility, or
volume as.a principal element. All permit requirements will
be met during the implementation of this remedial action.
It is determined that the remedy for this operable unit uses
permanent solutions and alternative treatment technologies
to the maximum extent practicable. The Arizona DEQ has
concurred with the remedy presented on this document.
Date
h E. Ayresx"
Regional Administrator
Region IX
RD/R52/021
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RECORD OF DECISION
CONCURRENCE PAGE
Site: Phoenix-Goodyear Airport, Goodyear, Arizona
The attached Record of Decision package for the Phoenix-
Goodyear Airport, Goodyear, Arizona, has been reviewed and I
concur with the contents.
Date
flary Ann Muirhead
Acting Deputy Regional Counsel
Office of Regional Counsel '
U.S. Environmental Protection
Agency, Region IX
Dt
Acting Director
Toxics & Waste Management Division
U.S. Environmental Protection
Agency, Region IX
S?% 1
Date
Harry £eraydarian
Director
Water Management Division
U.S. Environmental Protection
Agency, Region IX
Date/
/
Date
tfffurt/fssx
Director
Air Management Division
U.S. Environmental Protection
Agency, Region IX
w. Murray, Jr.
Assistant Regional Administ
Office of Policy and Manageme
U.S. Environmental Protection
Agency, Region IX
RD/R52/027
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CONTENTS
Page
Declaration for the Record of Decision 1
Site 1
Purpose 1
Basis 1
Description 1
Declaration 4
Record of Decision Concurrence Page 5
I. Site Description 1-1
II. Site History and Background II-l
Site History II-l
Site Characterization II-l
Receptors II-2
Toxicity II-6
III. Enforcement History III-l
IV. Community Relations History IV-J.
V. Alternatives Evaluation . " V-l
Listing of Alternatives V-l
Screening of Alternatives V-3
Evaluation of Alternatives V-6
VI. Selected Remedy VI-1
Statutory Determinations VI-1
Description VI-3
Appendix A. Index of Administrative Record
Appendix B. Responsiveness Summary
TABLES Page
1 State and Federal Applicable or Relevant and 3
Appropriate Requirements and Other Criteria
II-l Comparison of the Applicable or Relevant and II-3
Appropriate Requirements and Other Criteria
to Groundwater Data: Summary as of
August, 1986
II-2 Summary of Exposure Routes and Risks II-8
V-l Areal Extent of Pumping Alternatives V-4
-------
CONTENTS (continued)
I i
TABLES (continued) Page
V-2 Screening of VOC Removal Technologies V-5
V-3 Summary of Screening of Water End Use V-6
Alternatives
V-4 Cost Evaluation of Extraction and Monitoring V-8
Wells
V-5 Costs for Subunit A—Remedial Action with V-10
Water Reinjection
VI-1 - State and Federal Applicable or Relevant VI-2
and Appropriate Requirements and Other
Criteria
Follows
Page
Figures
1 Site Location Map i
II-l Current Cross Section II-l
View of Geology
II-2 Groundwater Contamination Map, II-5
Subunits B/C
II-3 Groundwater Contamination Map, II-5
Subunit A
II-4 Exposure Pathway and Receptor Summary II-6
V-l Potential Remedial Alternatives, V-l
Subunits A and B/C
V-2 Selected Remedial Alternatives, V-6
Subunits A and B/C
RD/R20/026
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I. SITE DESCRIPTION
The Phoenix-Goodyear Airport (PGA) site covers a total area
of about 35 square miles and is located about 17 miles due
west of Phoenix, Arizona, in the western part of the Salt
River Valley. The Section 16 Operable Unit covers about
750 acres and is located west of the City of Goodyear. The
towns of Goodyear and Avondale border the site on the east-
ern edge, occupying about 2 square miles. The remaining
land is presently used primarily for agriculture. The gen-
eral area had a combined population of about 30,000 people
in 1985.
The two major surface-water drainages within the area are
the Gila River to the south and the Agua Fria River to the
east. The Gila River flows perennially due to releases from
treatment plants. The Agua Fria River is dry most of the
year with occasional flows resulting from releases from
dams, irrigation tailwaters, or treatment plants. The Agua
Fria River drains south into the Gila River, which then flows
to the west.
Drinking water supplies, industrial water supplies, and irri-
gation water come solely from groundwater that is pumped
from the alluvial deposits of the western Salt River Valley '
underlying the entire area.
Section 16 contains the Loral Corporation facility (formerly
owned by Goodyear Aerospace Corporation) and the Phoenix-
Goodyear Airport (formerly operated by the U.S. Navy), both
of which have been identified as sources of contamination in
the southern area of the PGA site.
RD/R52/020 1-1
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II. SITE HISTORY AND BACKGROUND
SITE HISTORY
In 1981, the Arizona Department of Health Services discov-
ered that groundwater in the PGA area was contaminated with
solvents and chromium. Additional sampling of wells in
1982 and 1983 found 18 wells contaminated with trichloro-
ethene (TCE). As a result, the EPA added the PGA site to
the National Priorities List in September 1983. In 1984,
EPA began a remedial investigation of the Litchfield Airport
Area (presently known as the Phoenix-Goodyear Airport) to
characterize the site, discover the extent of the contami-
nation, and identify possible sources.
Historical data indicate two primary contributors to the
groundwater contamination in the Section 16 area: Goodyear
Aerospace Corporation (GAC), currently owned by Loral Cor-
poration, and activities carried out by the Navy at the
Litchfield Park Naval Air Facility. Historical data on waste
handling at GAC and PGA can be found in the Section 16
Operable Unit Feasibility Study.
Sampling data for groundwater identified two major areas of
contamination, a northern area and a southern area. Most of
the contamination in the southern area of the site was iso-
lated within Section 16. The Section 16 Operable Unit Feasi-
bility Study was initiated in 1987 to identify remedial
actions to contain further migration of contaminants and
deterioration of the aquifer.
Soil and soil gas sampling is currently being done to char-
acterize soil contamination in Section 16. Soil and ground-
water contamination will be addressed in the feasibility
study for the entire site.
SITE CHARACTERIZATION
The site is located in a region having a climate character-
ized by long, hot summers and short, mild winters. Relative
humidity is low, particularly during early summer, and the
rainfall averages about 7.1 inches per year. The average
daily maximum temperature in July is 107°F, the average
daily minimum temperature in January is 34°F, and the aver-
age yearly temperature is 70°F.
Groundwater is pumped from the alluvial deposits of the west-
ern Salt River Valley. These deposits consist of the Upper
Alluvial Unit, the Middle Fine-Grained Unit, and the Lower
Conglomerate Unit, as shown in Figure II-l. The Upper Allu-
vial Unit has been further subdivided into Subunit A, from
the surface to about 120 feet deep; Subunit B, from about
120 to 240 feet deep; and Subunit C, from about 240 to
360 feet deep. Subunits B and C are hydraulically connected.
RD/R52/020 II-l
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GOODYEAR AEROSPACE CORP.
FHOENIX-GOOOYEAR
MUNICIPAL AIRPORT
UNIOYNAMICS PHOENIX. INC.
;.„,.,.„„.. ,,w^i§iiiliii.,,.
V;N"/'v.'.•-;!-•' •.. ' '•'-,''.'". .:••'., . \ . • ' :'. ,••'•*• ',,„• '."..''
^^m^uyu^tmirS^^y^
FIGURE H-1
CURRENT CROSS-SECTION
VIEW OF GEOLOGY
EPA - JUNE 1987
1000 FT
-------
Most wells in the area pump water from a zone between 100
and 600 feet deep. Depth to the water table has varied in
the past, but recently has been measured between 40 and
100 feet below the ground surface. Groundwater flows in the
PGA area are divided at approximately Yuma Road. The north-
ern area has groundwater flows to the northwest, and the
southern area, including Section 16, has groundwater flows
to the southwest.
In addition to the TCE and chromium identified earlier, sev-
eral other compounds were found to contaminate the ground-
water. Among these are perchloroethene (PCE), 1,1-dichloro-
ethene (1-1 DCE), chloroform, carbon tetrachloride, and
arsenic. Table II-l identifies the wells tested, concentra-
tions detected, and the applicable federal or state standards
or other criteria. Not all wells tested in the PGA area are
listed in this table. The wells noted in this table were
selected as representative samples of groundwater quality.
Figures II-2 and II-3 show well locations and average con-
centrations of contaminants found in the Section 16 Upper
Alluvial Unit (Subunit A and Subunit B/C). The highest con-
tamination levels are found in the Subunit A, which is linked
to the Subunit B/C by conduit wells.
RECEPTORS
ENVIRONMENT
The environment of the PGA area is typical of the Phoenix/
Southwest region. Within the PGA site, there are no unique
habitats nor any threatened or endangered species. Native
vegetation at the site is sparse. However, located immedi-
ately south of the site, the lower Gila River represents
the important riparian habitat in southwestern Arizona.
Species that inhabit or migrate through the area include
four federally listed endangered species: brown pelican
(Pelecanus occidentalis), Yuma clapper rail (Rallus long-
irostris yumanensis), peregrine falcon (Falco peregrinus),
and the bald eagle (Haliaeetus leucocephalus).
The PGA area/ particularly near the Gila River, supports
viable hunting populations of mourning dove, white-winged
dove, Gambel's quail, and various waterfowl. The area is
especially popular for dove hunting and is known to support
one of the largest breeding dove colonies in the Southwest.
POPULATION
In 1985, the combined population of the Goodyear and Avon-
dale area was 30,000. The City of Goodyear has stated in
its general plan that the city expects to grow at a rapid
pace, exceeding 140,000 people within 20 years.
RD/R52/020 II-2
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Table II-l
COMPARISON OF THE APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
AND OTHER CRITERIA TO GROUNDWATER DATA: SUMMARY AS OF AUGUST, 1986
Well/Station ID Compound
16EMW-1 Trichloroethene
16EMW-2 1 , 1-Dlchloroethene
Trichloroethene
16EMW-3 1,1-Dlchloroethene
Trichloroethene
Concentration
(W/l)
Maximum
Average
Maximum
Average
Maximum
Average
Maximum
Average
Maximum
Average
1
1
9
<4
75
33
140
126
490
342
ARAR Exceeded
MCL,
MCL,
MCL,
MCL,
MCL,
MCL,
MCL,
MCL,
..
AWQC
AWQC
AWQC
AWQC
AWQC
AWQC
AWQC
AWQC
(Hf*)a
do" )
do"*)
do" )
do"*)
(10 )
do"*)
(10 )
Other Criteria,
Exceeded
ADHS
ADHS
ADHS
ADHS
ADHS
ADHS
ADHS
—
action
action
action
action
action
action
action
-.
level
level
level
level
level
level
level
Chromium (total)
16GMW-1
Trichloroethene
Maximum 513
Average 472
Maximum 41.7
Average 34
MCL, AWQC (toxicity)
MCL, AWQC (toxicity)
MCL, AWQC do"*)
MCL, AWQC (10 )
HA
•-longer term/
70 Kg,.lifetime
HA--longer term/
70 leg, lifetime
ADHS action
ADHS action level
Chromium (total)
Maximum 190
Average 150
MCL, AWQC (toxicity)
MCL, AWQC (toxicity)
HA—lifetime
16GMK-2
Chloroform
Maximum 12.8
Average <4.6
AWQC (10)
AWQC do" )
Carbon tetracblorlde
Maximum 5.1
Average <2
MCL, AWQC (10)
MCL, AWQC (10 )
ADHS action level
ADHS action level
Metaylene chloride
Trichloroethene
Maximum 13.2
Average <6.8
Maximum 24.9
Average 21
MCL, AWQC do"*)
MCL, AWQC (10 )
ADHS action level
ADHS action level
ADHS action level
ADHS action level
16GMW-3 1,1-Dlcbloroethene
Chloroform
Carbon tetrachloride
Trichloroethene
Maximum 12.8
Average 10.8
Maximum 9.3
Average 7.4
Maximum 5.1
Average 3.5
Maximum 155
Average 102.7
MCL, AWQC (10 )
MCL, AWQC (10 )
AWQC (10~*)
AWQC do" )
MCL, AWQC (10~*)
MCL, AWQC (10 )
MCL, AWQC do"*)
MCL, AWQC (10)
ADHS action level
ADHS action level
ADHS action IP
ADHS action 1.
ADHS action level
ADHS action level
RD/R52/020
II-3
-------
Table II-l
(continued)
Well/Station ID
Compound
Concentration
(Uq/1)
ARAB Exceeded
Other Criteria
Exceeded
16GMW-3
(continued)
GAC #2
Chromium (total)
Trichloroethene
Maximum 1,340 MCL, AWQC (toxicity)
Average 977 MCL, AWQC (toxicity)
Maximum 16
Average 9.8
MCL, AWQC (10~*)
MCL, AWQC (10 )
HA— longer term/
10 kg & 70 kg,
lifetime
HA— • longer term/
10 kg & 70 kg,
lifetime
ADHS action level
ADHS action level
GAC #3
GAC #4
Trichloroethene
Chromium (total)
Trichloroethene
Maximum 110
Average 44
Maximum 170
Average 170
Maximum 45
Average 12
MCL, AWQC
MCL, AWQC (10 )
MCL, AWQC (toxicity)
MCL, AWQC do"*)
MCL, AWQC (10 )
ADHS action level
ADHS action level
ADHS action level
ADHS action level
PLA #2
PLA #3
PLA #4
LPSC #4
LPSC #5
GF #27C
GF #3B
Trichloroethene
1,1-Dichloroethene
Trichloroethene
Arsenic
Chloroform
Chlorofora
Chloroform
Chloroform
Maximum 36
Average 12.4
Maximum 6
Average 6
Maximum 310
Average 256
Maximum 96
Average 96
Maximum 1.4
Average 1.4
Maxlaum 5.1
Average 5.1
Maximum 3.2
Average 3.2
Maxlaum 0.8
Average 0.8
MCL, AWQC (lO)
Mtt, AWQC (10 )
AWQC do"*)
MCL, AWQC (10~6)
MCL, AWQC (10 )
MCL, AWQC do"*)
MCL, AWQC (10 )
AWQC do"*)
AWQC do"*)
AWQC do"*)
AWQC do"6)
ADHS action level
ADHS action level
ADHS action level
ADHS action level
HA—all categories
RD/R52/020
II-4
-------
Table II-l
(continued)
Hell/Station ID Compound
GF #4A Trichloroethene
Concentration
(UO./D
Maximum 22
Average 10.5
ARAB Exceeded
MCL, AWQC do"6)
MCL, AWQC do"6)
Other Criv=»ia
Exceeded
ADHS action level
ADHS action level
COTRIR
Chloroform
Trichloroethene
Maximum 1
Average 0.77
Maximum 4.5
Average 3.3
AWQC (10)
AHQC (10 )
MCL, AWQC (10"6)
MCL, AWQC (10 )
DOMES? #3 Trichloroethene
PHILLIPS Trichloroethene
Maximum 2.3
Average 2.3
Maximum 12
Average 10.3
MCL
MCL, AWQC (10~fj
MCL, AWQC (10 )
ADHS action level
ADHS action level
PLUMB
Trichloroethene
Maximum 3
Average 3
MCL, AWQC do"6)
R.WOOD1
Trichloroethene
Maxima 3
Average 2.5
MCL
MCL
R.WOOD2
Trichloroethene
Maximum 2
Average <1.3
MCL
MCL
R5.6W3.5 Trichloroethene
Maximum 1.7
Average <1.1
MCL
MCL
RAYNER2
Trichloroethene
Maximo 3
Average 3
MCL, AWQC
RECMET2
Trichloroethene
S.SMITH2 Trichloroethene
Maxima 6
Average 4.4
Maxima 3
Average 2
MCL, AWQC (K)
MCL, AWQC do" )
MCL, AWQC do"6)
Ma
ADHS action level
SHAWVER
Trichloroethene
Maximum 3
Average 3
MCL, AWQC (10 )
a -6 "6
AWQC(10 )«the ambient water quality criteria that results in a 10 excess lifetime caacer risk.
5
ADHS action level»Arizona Department of Health Services action level.
CAWQC (toxicity)-the ambient water quality criteria for human toxieity.
dHA«Health advisory.
MCL-Maxlaum contaminant level.
MCL«Maxlaum contaminant level goal.
RD/R52/020
II-5
-------
LEGEND
'WELL IDf
^x* TCE CONC M9/I
PLA 3
ND-
^/ ' "" ^Cr CONC pg/l
^WELL LOCATION
ND = NOT DETECTED
NOTE: CONCENTRATIONS OF CONTAMINANTS
ARE BASED ON DATA COLLECTED
DURING MARCH AND JUNE 1987.
CONCENTRATIONS ARE SINGLE EVENT.
O1 600* 1000'
FIGURE H-2
CROUNDWATER CONTAMINATION MAP
SUBUNITS B/C
PHOENIX-COODYEAR AIRPORT
W63602.R4
-------
TCE CONC (ug/D
r CONC (mg/l)
ND EMW17
0.007
WELL LOCATION
ND = NOT DETECTED
NOTE: CONCENTRATIONS OF CONTAMINANTS
ARE BASED ON DATA COLLECTED
DURING 1906 AND 1987.
CONCENTRATIONS ARE MEAN OR
SINGLE EVENT.
600* 10001
FIGURE Jl-3
CROUNDWATER CONTAMINATION MAP
SUBUNIT A
PHOENIX-COODYEAR AIR
W63602.RA .
-------
All drinking water wells currently in use for municipal sup-
ply meet applicable.federal and state health standards.
However, future population growth will result in greater
usage of groundwater resources, particularly in the contami-
nated areas. Use of the groundwater will result in a poten-
tial exposure to contaminants through the means described in
Figure II-4, if no action is taken at this site and contami-
nation migrates to areas that contribute to municipal
groundwater supply.
TOXICITY
ORGANIC COMPOUNDS
This group of compounds includes most of the contaminants
identified at the PGA site. Several of these compounds,
carbon tetrachloride, chloroform, 1,1,1-trichloroethane,
perchloroethene, and trichloroethene, may produce liver
injury. Carbon tetrachloride and chloroform have more seri-
ous effects on the liver than trichloroethene and perchloro-
ethene (Doull et al., 1980). Carbon tetrachloride,
chloroform, perchloroethene, and trichloroethene have been
classified by the EPA Carcinogen Assessment Group (CAG) as
probable human carcinogens via ingestion (U.S. EPA, 1986a)..
Exposures to the above compounds through inhalation may
result in central nervous system depression, including anes-
thesia. TCE has been used as an anesthetic (National
Research Council, [NRC] 1977). other effects may include
irritation of the mucous membranes of the nose and throat
and irritation to the eyes (NRC, 1980). Trichloroethene and
perchloroethene are also classified as probable human car-
cinogens by CAG via the inhalation route (U.S. EPA, 1986a).
1,1-Dichloroethene and trans-l,2-dichloroethene exhibit simi-
lar toxic effects to humans through inhalation and ingestion
exposures. These compounds have anesthetic properties, and
exposures to high concentrations may cause nausea and vomit-
ing (U.S. EPA, 1985a). The CAG has classified
1,1-dichloroethene as a possible human carcinogen for both
inhalation and ingestion exposure routes (U.S. EPA, 1986a).
INORGANIC COMPOUNDS
This group of compounds includes metals. Some of the inor-
ganic compounds detected at the PGA site, such as chromium,
are much more toxic than others.
CHROMIUM
Chromium has been identified in some water samples taken
from the site in both the trivalent and hexavalent states.
RD/R52/020 II-6
-------
MEDIA
DIRECT EXPOSURE PATHWAY > RECEPTOR
GROUNDWATER
—> ingestion by residents who use private
wells for potable water supply
—> Inhalation of volatiles stripped from
the drinking water during in-home uses
such as bathing and cooking
-> dermal contact with contaminated ground-
water from resident's private wells
W63602.RA
FIGURE IJ.-4
EXPOSURE PATHWAY AND
RECEPTOR SUMMARY
I'llOf NIX (.(H)I)YI AK A I KM
SECTION l(i GUIS
-------
Chromium compounds in the trivalent ( + 3) state are of a low
order of toxicity. In the hexavalent (+6) state, chromium
compounds are irritants and corrosive and can enter the body
by ingestion, inhalation, and through the skin (Sittig, 1981) .
Hexavalent chromium may cause liver and kidney damage, inter-
nal bleeding, and respiratory disorders (U.S. EPA, 1985b).
Hexavalent chromium has been designated by the CAG as a human
carcinogen, via the inhalation route (U.S. EPA, 1986a).
RISK
Risk is a function of both toxicity and exposure. At present,
the exposure to contaminated groundwater is limited, and the
population and environment are not in any immediate danger.
However, future migration of the contaminants could affect
plant and animal life, and future use of contaminated ground-
water will result in heightened risks as shown in Table II-2.
The risk associated with exposures to contaminated groundwater,
particularly for future use scenarios, is an excess lifetime
cancer risk. This risk can go as high as 2 x 10-3 (two excess
lifetime cancer occurrences per 1,000 people exposed over
the course of a 70-year lifetime). There does not appear to
be an ingestion risk from exposure to noncarcinogens. More
information on health effects associated with contaminants
found at the PGA site can be found in the Preliminary Public
Health Endangermen-t Assessment in the administrative record.
RD/R52/020 II-7
-------
Table II-2
SUMMARY OF EXPOSURE ROUTES AND RISKS
Media
Exposure Setting
Exposure Risk
Results
Groundwater Residential—Current and Ingestlon
Potential
For the Goodyear municipal wells (COG 01,2,3,6), there Is an excess
lifetime cancer risk of 2 x 10 based on the maximum trlchloro-
ethylene concentration for these wells. There does not appear to
be a risk from the Intake of noncarcinogens. COG #1,2,3,6 are
blended to provide water as demanded.
I
oo
For the private domestic wells PLUMB, SHAUVER, and DOMEST3, the risk
due to trichloroethylene contamination of these wells can only be
qualified because fewer than three samples were collected from eai-h
well. A carcinogenic health risk may be present; however, the
exact nature of the risk cannot be identified. There does not
appear to be a risk from the Intake of noncarcinogens.
Inhalation
o The risk from inhalation of volatlles released from the groundwater
In the course of in-home uses such as cooking, bathing, etc., cannot
be quantified. However, it should be recognized that this exposure
could contribute to the overall,risk from the use of contaminated
groundwater.
Residential—Potential
Only
Ingest ion
The GAC monitor wells follow with excess lifetime cancer risks of
-4
2 x 10 based on the maximum concentration of 1 ,l-d(cliloroethene,
2 x 10 for carbon tetrachloride, 3 x 10 for chloroform, and
5 x 10 for trlchloroethylene, all based on the-maximum concen-
tration of each constituent from the three wells. There does not
appear to be a risk from the Intake of noncarcinogens.
For the EPA monitor wells, there Is an excess lifetime cancer risk
of 2 X 10 for 1,1-dlchloroethene and 1 X 10 for trlchloroethem-
based on their maximum concentrations, due to exposure through
Ingestlon of groundwater. There does not appear to be sk from
the intake of noncarcinogens.
-------
Table 11-2
(continued)
Media
Exposure Setting
Exposure Risk
Results
Groundwater Residential—Potential
Only
IngestIon
I
vo
Other wells In the area that presented an excess lifetime cancer
risk due to trlchloroethylene include the following:
- GAC «3: 3 X 10 based on the maximum concentration
- GAC 14: 1 X 10 based on the maximum concentration
- PLA 12: 1 X 10 based on the maximum concentration
- PLA 13: 1 x 10 based on the maximum concentration
There was also an excess lifetime cancer risk of 6 X 10 tor
COG #5 (fire control well) due to the maximum concentration of
arsenic. There does not appear to be a risk from the Intake of
noncarclnogens.
The risk from Inhalation of volatlles released from the groundwatet
In the course of in-home uses such as cooking, bathing, etc., can-
not be quantified. However, this exposure could contribute to the
overall risk from the use of contaminated groundwater.
Assumptions: Dally water Intake for 0-6 years, 1.0 liter/day; 6-18 years, 1.4 liters/day; 18-70 years, 2.0 liters/day.
Lifetime average dally Intake for drinking water - 0.029 liter/kg of body weight/day based on a 70 kg individual
consuming 2 liters/day of water over the course of a 70-year lifetime.
-------
III. ENFORCEMENT HISTORY
In Section 16, two responsible parties have been identified
as the major sources of groundwater contamination, Goodyear
Aerospace Corporation (GAC) and the Department of Defense
(for past naval operations).
GAC has been participating in the RI/FS since 1984. Its
efforts have been concentrated on determining the extent of
soil contamination at the facility and the extent of ground-
water contamination underneath the GAC facility and the PGA.
A history of EPA enforcement actions toward GAC includes:
o July 23, 1982—RCRA Section 3007/CERCLA
Section 104 request for information issued to GAC
o March 27, 1984—General notice letter sent to GAC
from EPA
o March 27, 1984—RCRA Section 3013/CERCLA Section 106
Administrative Order on consent issued to GAC
o December 20, 1984—Violation of the Clean Water
Act issued to GAC from EPA
*
o January 14, 1986—Violation of the Clean Water Act
issued to GAC from EPA
o March 19, 1986—CERCLA Section 106 Administrative
Order on consent signed by GAC and EPA
The U.S. Corps of Engineers had begun researching Navy
activities at the airport and believed that the Navy is a
potentially responsible party for the groundwater
contamination emanating from the PGA area. The Navy had
sold the facility to the City of Phoenix in 1968. The
U.S. Corps of Engineers was assigned in May 1985 to
represent the Department of Defense on the Phoenix-Goodyear
Airport Interagency Committee, which was established by EPA
to involve state and local agencies as well as responsible
parties in CERCLA actions at the site.
GAC is currently conducting RI activities at the site in
accordance with the March 19, 1986, order. These activities
will be completed by the end of the calendar year.
RD/R52/020 ' III-l
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IV. COMMUNITY RELATIONS HISTORY
The following is a list of community relations activities
conducted by the U.S. EPA at the PGA Superfund site (formerly
the Litchfield Airport Area [PLA] site):
o EPA conducted interviews with Goodyear and Avondale
residents and state and local officials in 1984 to
improve EPA's understanding of community concerns.
These interviews provided the basis for the Phoenix-
Litchfield Airport Area Community Relations Plan
released in October 1984.
o EPA established information repositories at the
Avondale Public Library, Phoenix Public Library,
and the Arizona Department of Health Services.
EPA updated repositories periodically with fact-
sheets and other relevant documents.
o EPA established a computerized mailing list with
over 200 addresses of interested individuals.
o EPA contributed PGA-related information to
Groundwater Quality Update, a newsletter that pro-
vides information about groundwater quality to '
interested parties, prepared and distributed by
the Arizona Department of Health. Services.
o EPA distributed a factsheet in July 1984 which
provided an overview of the Superfund process, a
brief description of the PGA site contamination,
and described proposed remedial investigation/
feasibility study (RI/FS) activities.
o EPA held a community meeting on August 1, 1984, to
provide an overview of the Superfund process, infor-
mation on past site activities, and outlined future
RI/FS activities.
o EPA distributed an "Update on Site Activities"
factsheet in February 1985 which described ongoing
RI/FS activities including water level measurement
and water quality sampling, soil boring and sampling,
well installation, and computer modeling.
o EPA released the "Water and Soil Sample Results"
factsheet in June 1985 which reported the results
of the soil and water sampling, and discussed how
this information would be used in the second phase
of the RI/FS.
o EPA held a community meeting on February 19, 1986,
to report the remedial investigation Phase I
RD/R52/020 IV-1
-------
results, and to discuss the additional information
needed to complete the RI and the plan for obtain-
ing this information during the upcoming RI Phase I
activities.
o EPA sent out a factsheet in January 1987 which
provided groundwater sampling results and discussed
.the Operable Unit Feasibility Study (OUFS) .
o EPA distributed a factsheet in May 1987 announcing
the release of the OUFS and the beginning of a
public comment period for the study, as well as
announcing a community meeting on June 4, 1987.
o EPA held a public comment period from June 2, 1987,
to July 2, 1987, on the draft OUFS and prepared a
responsiveness summary to address the comments
received.
o EPA announced the public comment period on the
draft OUFS and the public meeting with a public
notice placed in Goodyear's weekly newspaper
Westsider which ran on Thursday, May 28, 1987, and
Thursday, June 4, 1987.
In addition, EPA will continue to conduct ongoing community.
relations activities at the PGA site throughout the duration
of the comprehensive RI/FS.
RD/R52/020
RD/R52/020 IV-2
-------
V. ALTERNATIVES EVALUATION
LISTING OF ALTERNATIVES
A wide range of alternatives was identified for the Sec-
tion 16 Operable Unit. These alternatives were separated
into three groups: groundwater, water treatment, and water
end use (see Figure V-l). Groundwater alternatives were
selected to compare the relative values of containing or
pumping different areas of groundwater contamination at dif-
ferent rates. Treatment alternatives were selected based on
institutional requirements and the best available technology.
Water end use alternatives were selected based on the feasi-
bility of delivering the water and the distance to sites
capable of accepting the estimated flows. As shown in Fig-
ure V-l, if groundwater pumping and rehabilitation alter-
natives are selected, an appropriate water treatment alter-
native and a water end use alternative would also be selected.
The no-action and containment alternatives will not require
associated water treatment or end use alternatives.
Although chromium is above the federal primary drinking water
standard in portions of the aquifer, the extent of the chro-
mium contamination is not precisely known at this time.
Therefore, treatment of the chromium contamination will be '
addressed in the final remedy. In the interim, all water
extracted from the aquifers will be blended and then treated
for VOC's and discharged to the appropriate end use location.
This discharge will meet all federal primary drinking water
standards for all contaminants, including chromium since the
water containing chromium will be blended with water free of
chromium. This is possible since the volume of water being
extracted and treated creates a stream that lowers the chro-
mium concentration to acceptable levels for the interim per-
iod. This treatment scheme is only an interim solution, and
all contamination will be fully addressed in the final remedy.
GROUNDWATER ALTERNATIVES
The groundwater alternatives are:
o No action
o Containment of the contaminated groundwater by use
of a slurry wall extending to the Middle Fine-Grained
Unit and surrounding a range of areas within
Section 16
o Extraction of contaminated groundwater from four
potential areas. These areas were chosen based on
location of contaminant disposal and extent, of
groundwater contamination.
RD/R52/023 V-l
-------
GROUNDWATER
GROUNDWATER REHABILITATION
ALTERNATIVES
ALTERNATIVES
WATER
ALTERNATIVES
WATER
TREATMENT
TECHNOLOGIES
WATER
END USE/DISPOSAL
ALTERNATIVES
NO ACTION
H
CONTAINMENT
PUMPING
QAC
OAC 4 PGA
SECTION 16
SECTION 16-
ACCELERATED
NO REHABILITATION
MEET ARAR'S
MEET BACKGROUND
NO TREATMENT
MEET ARAR'S
MEET BACKGROUND
1
•
^
—
STRIPPING
(STEAM/AIR)
CARBON
ADSORPTION
REVERSE
OSMOSIS
DISTILLATION
LIQUID-LIQUID
EXTRACTION
CRITICAL FLUID
EXTRACTION
PHOTOLYSIS
BIOLOGICAL DEGRADATION
(AEROBIC/ANAEROBIC)
•L
AGRICULTURAL
•L
INDUSTRIAL
H
•\
H
H
MUNICIPAL
RECREATIONAL
SURFACE DISCHARGE
GROUNOWATER REINJECTION
I lUUHt V I
POTENTIAL REMEDIAL ALTERNATIVES
8UBUNIT8 A AND B/C
PMOENIX-GOODVEAR AIRPOH I
SECTION 10
W83802 H4 >
-------
GROUN ATER
ALTERNATIVES
GROUNDWATER
REHABILITATION
ALTERNATIVES
I
ALTERNATIVES
WATER
TREATMENT
TECHNOLOGIES
WATER
END USE/PIS ^
ALTERNATIVES
NO ACTION
CONTAINMENT
NO REHABILITATION
PUMPING
QAC ft PGA
SECTION ie
SECTION Ifl-
ACCELERATED
MEET ARAR'8
MEET BACKGROUND
NO TREATMENT
1-H
H MEET ARAR'i
MEET BACKQROUN
—1
HIM a iMirrinu
CARBON
ADSORPTION
m
•\
H
SURFACE OISCHARQE
REINJECTION
FIGURE V-2
SELECTED REMEDIAL ALTERNATIVE
SUBUNITS A AND 8/C
PHOENIX-OOODYEAR AIRPORT
SECTION t6
W63602.R4 -«
-------
Extraction of groundwater from Subunit A within
the Upper Alluvial Unit beneath source areas at
the GAC facility only.
Extraction of groundwater from Subunit A within
the Upper Alluvial Unit beneath source areas at
the GAC and PGA facilities.
Extraction of groundwater from Subunit A beneath
all of Section 16, with the exception of the area
northwest of the runway at the PGA. (Groundwater
monitoring indicates levels of contaminants below
ARARs in Subunit A for the area northwest of the
runway.)
Extraction of groundwater at an accelerated rate
from aquifers in Subunit A beneath all of Section 16,
with the exception of the area northwest of the
runway at PGA. This would be accomplished by using
more wells and higher pumping rates. (Groundwater
monitoring indicates levels of contaminants below
ARARs in Subunit A for the area northwest of the
runway.)
Each extraction alternative is associated with two ground- .
water level of treatment alternatives that are directly
related to the duration of pumping. The longer the period
of pumping the more pore volumes of groundwater in the cap-
ture zone will be removed, thus the greater the cleansing of
the aquifers. The groundwater rehabilitation alternatives
for Subunit A of the Upper Alluvial Unit are:
o Removal until water from monitoring wells is of a
quality that meets ARARs
o Removal until levels of VOC's in water from monitor-
ing wells are below detection limits, which is the
background quality of groundwater in the area
WATER TREATMENT TECHNOLOGIES
The possible technologies identified to treat water are:
o Air stripping
o Activated carbon
o Reverse osmosis
o Distillation
o Critical fluid extraction
o Liquid-liquid extraction
o Photolysis
o Aerobic biological treatment
o Anaerobic biological treatment
o Steam treatment
o Wellhead treatment
RD/R52/023 V-2
-------
WATER END USE ALTERNATIVES
The water end use alternatives are:
o Reinjection
o Surface discharge
The possible uses identified are:
o Reinjection up to 2 miles from the site in a manner
that will not have any deleterious effect on the
remedial action
o Discharge to the City of Goodyear
o Discharge to the Agua Fria River
o Discharge to GAC
o Discharge to Arlington Canal Co.
o Discharge to Buckeye Irrigation District
o Discharge to City of Avondale
o Discharge to City of Phoenix
o Discharge to Cotton Tree Apartments
o Discharge to Estrella Golf Course
o Discharge to Goodyear Farms, Inc.
o Discharge to Litchfield Park Service Company
o Discharge to Maricopa County WCD
o Reinjection for plume control
o Discharge to Roosevelt Irrigation District
o Discharge to Salt River Project
o Discharge to St. Johns Irrigation District
o Discharge to Valley Utilities Company
o Reinjection at Unidynamics
SCREENING OF ALTERNATIVES
As promulgated under CERCLA and SABA/ remedial actions are
those responses to releases that are consistent with a per-
manent remedy to prevent or minimize the release of hazard-
ous substances, pollutants, or contaminants so they do not
migrate to cause substantial danger to present or future
public health or welfare or the environment. SARA, Sec. 121,
states further, "Remedial actions...shall attain a degree
of cleanup of hazardous substances, pollutants, and contami-
nants released to the environment and of control of further
release at a minimum which assures protection of human health
and the environment. Such remedial actions shall be relevant
and appropriate under the circumstances presented by the
release or threatened release of such substance, pollutant,
or contaminant." SARA also states that remedial actions
should be favored that permanently and significantly reduce
the volume, toxicity, or mobility of hazardous substances,
pollutants, and contaminants. The offsite transport and
disposal of hazardous substances or contaminated materials
without such treatment should be the least favored alterna-
tive remedial action where practicable treatment technologies
are available.
RD/R52/023 V-3
-------
Alternatives are screened based on their ability to meet the
above-stated requirements and to meet the objective of the
operable unit. The objective is to control the migration of
contaminants within the Section 16 boundaries while being con-
sistent with the final remedial action for the entire site.
GROUNDWATER ALTERNATIVES
The no-action and containment alternatives must be evaluated
by law and were retained for later evaluation.
The pumping alternatives were evaluated based on their abil-
ity to clean up the targeted Section 16 area. Table V-l
summarizes the findings.
Table V-l
AREAL EXTENT OF PUMPING ALTERNATIVES
Gallons Relative Area
Pumping Target Cleanup per (percent of
Alternative Subunit Area (acres) Minute largest target area)
GAC A 120 200 24
GAC and PGA A 325 ' 250 65
Section 16 A 500 300 100
Section 16— A 500 1,200 100
Accelerated
Pumping Alternative GAC would not adequately protect the
downgradient groundwater sources by covering only 24 percent
of Subunit A. Since there are high levels of contamination
in Subunit A throughout the Section 16 area, it is reason-
able to provide the most efficient means of removing as much
contamination as possible from the entire area. For this
reason the GAC alternative was dropped from further consid-
eration. The remaining pumping alternatives were evaluated
in detail.
TREATMENT ALTERNATIVES
Table V-2 presents an evaluation of the technologies for VOC
removal and screens out those that are not applicable. Air
stripping and activated carbon adsorption were retained for
detailed evaluation. The other technologies identified were
dropped from further consideration for a variety of reasons
RD/R52/023 V-4
-------
Table V-J
OP voc REMOVAL TECHNOLOGIES
SECTION U ROD
Proceea
Description
Air Stripping
Activated Carbon
Adsorption
Reverae Oaaoala
DIatlllatlon
f Liquid-Liquid
Ln Extraction
Critical fluid
Extraction
Pbotolyal*
Aerobic Biological
Anaerobic
Biological
Steam Stripping
State of
Development
Commercial
Commercial
Commercial
Commercial
Limited
Commercial
Limited
Commercial
Limited
Commercial
Commercial
Commercial
Ability to Meet
Otecbarce Standard*
Capable of VOC removal
exceeding 99.9 percent
Capable of VOC removal
exceeding 99.9 percent
Relatively poor
performance for VOC'a
Capable of achieving
very high VOC removal
Unknown--pollahlng 1*
u*ually required
Unknown- -a 1 though
unlikely to reduce
below 100 ppb
' Unknown
"iimi compound* not
readily biodegradable
Nay not consistently
meet standards
Capable of VOC removal
exceeding 99.9 percent
Performance
Record
Excellent
Excellent
Poor for VOC
remove I
Good on high
concentration
at reams; not
appropriate for
low concentra-
tion streams
Good, but
ability to
meet dtacharge
requirement*
la unknown
Limited— few
large-acale
application*
Limited- -com-
plete
conversion
unlikely
Variable
performance
for VOC'a
Variable
performance
for VOC'a
Excellent
Relative Coat*
Capital Operation
Low Low
to
Moderate
Low Moderate
to
High
High High
Moderate Very High
High Very High
Very High Moderate
to
•t*>
Unknown None
Ulgb High
High High
High Hlgb
Waste Streams
Air exhaust (can be
carbon treated)
Carbon containing
organlca requires
regeneration or
replacement
Producee a concen-
trate at ream that
requires additional
treatment
Exhaust containing
organlca
Solvent with extracted
organlca
None
May produce more
harmful byproducts;
some appllcattona
require very long
residence times
Sludge produced tbst
require* disposal
Sludge produced
Air exhauat
Additional Commenta
Commonly uaed for removal of VOC'a
at low concentration
Relatively poor carbon utilisation
for treatment of stream* with very
low organic concentratlooa'
Generally uaed for removal of aslts
and high molecular weight organlca
Generally uaed for treatment of
concentrated streams where high
degree of separation 1* required
Produce* s solvent stream with
organlca that requlrea additional
treatment; require* uae of
potentially bsxardoua solvents
None
None
May not be stable, susceptible to
•bock, temperature-dependent,
acclimation la Important
May not be ateble, susceptible to
shock, temperature -dependent,
acclimation Is Important
Not used for this type of
application
Retained for
further Analyula
Yes
Yes--uaelul for vapoi
and aqueou* phaae Voc
removal
No—poor performance
for VOC removal
No-*not approprldie
for low levela of
contaminant*
No--ablllty lo Steel
discharge rerqulic-
menta la unknown
No--poor peflolodntc
for thla applli.41 Ion
No- -lack of Jevclopofiu
performance
No--varl*ule
performance
No—variable
performance
No* -not demount I 41 t«l
fur removal ol low
concent rat lona ol
VOC'a
Wellhead
Treatment
Commercl*! Variable depending on
Variable
Variable
Variable
Variable
-------
including poor, variable, or unproven performance, institu-
tional and management constraints, or inapplicability to
expected contaminant concentrations. Chapter 7 of the
Section 16 Operable Unit Feasibility Study provides the
methodology for -the screening of treatment alternatives.
WATER END USE ALTERNATIVES
Based on water quality, potential interest by end users, and
future water requirements of end users, the water from Subunit
A was screened, with the results shown in Table V-3. Because
of the high levels of TDS in Subunit A (about 3,900 ppm as
compared to the secondary MCL of 500 ppm), water from this
subunit can only be used for reinjection after treatment as
it cannot be used for drinking or irrigation purposes.
There are no other suitable uses for this water.
Table V-3
SUMMARY OF SCREENING OF
WATER END USE ALTERNATIVES
Use Subunit A
Agricultural Eliminated
Industrial Eliminated
Municipal Eliminated
Recreational Eliminated
Groundwater Recharge Retained
Surface-Water Discharge Eliminated
aRetained for reinjection into Subunit A only.
In summary, the only end use alternative that appears to be
available is reinjection.
EVALUATION OF ALTERNATIVES
The remaining alternatives are shown in Figure V-2. A short
summary of the technical and economic evaluation of each
alternative follows.
GROUNDWATER ALTERNATIVES
No Action Alternative
The no-action alternative would allow the groundwater con-
tamination to spread over an ever-widening area and would
RD/R52/023 V-6
-------
likely have continuing adverse environmental and health
consequences. These include exposure of carcinogens and
other harmful contaminants through ingestion of water and
soil and inhalation of soil gas and gas released from pumped
groundwater.
Containment Alternative
The containment alternative will accomplish the purpose of
isolating contaminants in the contained area for some period
of time but would not accomplish the objective of perma-
nently reducing waste volume or toxicity. Institutional
controls would be necessary to prevent usage of contained
groundwater in the future. A containment wall could be
constructed to surround GAC and PGA, or all of Section 16.
They have been demonstrated at numerous areas to contain
groundwater under saturated conditions; however, there is no
guarantee of continuous or permanent containment. The use-
ful life of containment walls is unknown, but is expected to
be more than 100 years. Containment walls as deep as 325
feet have been constructed, but with great difficulty. If a
containment wall were to be constructed at this site, it
would take about 2 to 3 months to build around the GAC and
PGA area, or about 9 to 12 months to build around the
Section 16 area. No significant safety hazards are expected
during construction. If after construction the containment'
wall failed, there would be a threat to public health and
the enviro-nment as contamination moves offsite and pollutes
water supplies. Containment walls of the depth required at
the PGA site are difficult to construct, and cost estimates
for this alternative range from $111 million to $148
million, making it an extremely expensive alternative. It
cannot be guaranteed that contaminants would be permanently
contained within slurry walls.
Pumping Alternative
The pumping alternatives also accomplish the objective of
stopping migration of contaminants in Section 16. When
coupled with treatment, they also will reduce the volume,
mobility, and toxicity of the groundwater. Pumping to
extract contaminated groundwater would prevent migration of
contaminants from the chosen pumping area. This technology
has been demonstrated to be successful in other areas.
However, aquifer rehabilitation estimations are based on
hydrogeologic principles and regional flow characteristics.
There is some uncertainty as to the time required for
rehabilitation due to limited knowledge of the stratigraphy.
Analysis of water samples from monitoring wells for contam-
inant levels will indicate aquifer cleanup. The period esti-
mated for,cleanup for Subunit A under GAC and PGA is 57 years,
for Section 16, 82 years, and for Section 16—accelerated,
37 years. Pumping rates for these alternatives are found in
RD/R52/023 V-7
-------
the Operable Unit Feasibility Study. Operation is relatively
simple and is not expected to signficantly affect the alter-
native's reliability. It is likely that during the remedial
action, some components will require maintenance or replace-
ment. No impediments to well construction are foreseen, and
no significant safety hazards are expected during construc-
tion. If pump failure occurs, there would be no release of
contaminants that could pose a threat to public health or
the environment. Table V-4 summarizes the capital costs
associated with these options.
Table V-4
COST EVALUATION OF EXTRACTION AND MONITORING WELLS
Cost
Pumping Pumping Pumping
Item GAC and PGA Section 16 Section 16-ACC
Extraction Wells $110,000 $275,000 $600,000
and Pumping
Monitoring Wells 60,000 150,000 360,000
Total $170,000 $425,000 - ' $960,000
TREATMENT ALTERNATIVES
Both air stripping and activated carbon adsorption achieve
the desired goal of reducing volume and toxicity of the
groundwater sufficiently to meet the applicable and appropri-
ate requirements and will likely exceed these requirements.
Treatment of contaminated groundwater, either by air strip-
ping or the use of granular activated carbon, has been shown
to be very effective with removals of organic often exceed-
ing 99.9 percent. These processes are relatively predictable,
and they have been used successfully at a number of CERCLA
sites. Equipment is relatively easy to operate once initial
adjustments have been completed. Operator training will be
required. Occasional attention for adjustment, monitoring,
and testing will be required. With industrial-grade compon-
ents and regular preventive maintenance, process integrity
should be 10 years or more. Scaling of air stripping tower
internals has been a problem at some sites. A small amount
of an anti-sealant, such as hypochlorite, would be required
to remedy this.
RD/R52/023 V-8
-------
Numerous vendors are available to produce, the process
components. Conventional materials for construction are
required. All equipment items can be shop-fabricated and
skid-mounted, making field erection easier. Construction of
either process could be completed within one year. The
startup period may take several days. Catastrophic failure
of components are unlikely, and any threat to public health
and the environment are relatively low. Air emission con-
trols will be placed on the air stripping towers for two
reasons. First, SARA states that a remedy should signifi-
cantly reduce the toxicity, mobility, and volume of contami-
nants. By just removing VOC's from water and placing them
into the atmosphere, none of these objectives are satisfied.
In addition, Maricopa County Air Pollution Control Board
requires that all new plants with air emissions "will ade-
quately dilute, reduce, or eliminate the discharge of air
pollution to adjoining property." This requirement is also
known as reasonably achievable control technology (RACT),
and in this case, RACT is air emissions controls such as
activated carbon adsorption or thermal degradation. The ;
costs associated with each treatment alternative are
summarized in Table V-5.
END USE ALTERNATIVES
As discussed previously, in the Screening of Alternatives >
section, for the Subunit A water, the only viable alterna-
tive is reinjection back into the Subunit A aquifer. The
number and location of reinjection wells would need tp..be
studied.
Injection into aquifers via wells has been done successfully
in the past. Operations are simple, but require maintenance
from time to time. Periodic redevelopment will prevent clog-
ging of the wells, thus maintaining the wells' ability to
accept the generated flow. Redevelopment will require a
temporary shutdown. Drilling and developing wells is rou-
tine, and the construction period, including construction of
the conveyance system, is expected to be less than 18 months.
No threats are expected to public health or the environment
during construction or in the event of system failure. Costs
are included in Table V-5 along with the treatment alterna-
tives.
RD/R52/023
RD/R52/023 V-9
-------
Table V-5
COSTS FOR SUBUNIT A
REMEDIAL ACTION WITH WATER REINJECTION
Pumping Alternative
Treatment Method
CAPITAL COSTS
Air Stripping:
To ARAR
To Background
Granular Activated Carbon:
To ARAR
To Background
GAC & PGA
$2,077,500
2,139,500
2,032,500
2,032,500
Section 16 Section 16-Accelerated
$2,358,500
2,438,500
2,338,700
2,338,700
$5,043,100
5,222,100
5,226,500
5,226,500
OPERATING COSTS
b
Air Stripping:
To ARAR 765,500 800,200
To Background 787,400 872,300
Granular Activated Carbon:
To ARAR 3,532,400 - 4,203,900
To Background 3,532,400 4,203,900
1,521,500,
1,555,700
15,085,700
15,085,700
aCosts are shown as present worth at a 10-percent rate of return.
'costs for air stripping include air emission control.
RD/R63/001
V-10
-------
VI. SELECTED REMEDY
STATUTORY DETERMINATIONS
CERCLA and its reauthorization, known as SARA, requires that
permanent reductions of contaminants through treatment be
preferred over containment alternatives.• It also requires
that Applicable or Relevant and Appropriate Requirements
(ARARs) be used to determine the treatment levels. By achiev-
ing these requirements, the selected remedy for the Section
16 Operable Unit reduces the present and future risks associ-
ated with use of the groundwater in the Section 16 area. By
reducing the contaminant levels and restricting their mobil-
ity, this remedy protects both human health and environmental
quality.
Table VI-1 shows the ARARs identified for the groundwater
and the proposed treatment levels. In all cases, contami-
nant levels found in Section 16 Subunit A wells are greater
than the Safe Drinking Water Act maximum contaminant levels
(MCL) and the Arizona Department of Health Services action
levels.
While the selected remedy satisfies the requirements for
treatment and risk reduction, it does so in the most economi-
cal manner. Since Subunit A is the most contaminated aqui-
fer, the entire Section 16 area will be treated and pumped
to prevent lateral and vertical migration. Although the
recommended alternative at the beginning of the public com-
ment period called for limited pumping and treatment of water
from Subunit B/C this water is much less contaminated and
will be pumped and treated as part of the current industrial
practice until the final remedy is chosen next year. This
reduces pumping and well costs while capturing the most con-
taminated water.
Of the proven technologies, air stripping proved to be the
most economical treatment method available, both for capital
and operating costs. It will also reduce residual wastes to
a minimum.
Reinjection proved to be the only viable alternative for
Subunit A water.
By reducing migration of contaminated groundwater outside of
Section 16 and permanently reducing the levels of contamination
in Section 16, the risks associated with use of the water
are reduced to acceptable levels. The selected remedy satis-
fies the requirement of reducing the mobility, toxicity, and
volume of contaminated water. It does so by using treatment
technology to the maximum extent practicable and does so in
a cost-effective manner.
RD/R52/024 VI-1
-------
Table VI-1
STATE AND FEDERAL
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS*
(concentrations in ppb)
AND OTHER CRITERIA
Compound
Trichloroethylene
1,1,1-Trichloroethane
1,1-Dichloroethylene
Perchloroethylene
Trans-1,2-dichloroethylene
Carbon tetrachloride
Chloroform
Chromium
Arsenic
SDWA
MCL
5
200
7
50
50
SDWA
MCLG
0
200
7
Proposed
MCL
Proposed
MCLG
AWQC
Drinking Water
Only
ADHS
Action
Level
5
200
1
3
70
0.5
120
50
Proposed DW
Treatment
Level
5
200
7
3
70
5
0.5
50
I
N>
Clean Water Act requirements will be determined during NPDES review.
Source is not a byproduct of municipal water supply chlorination.
NOTES: ADHS—Arizona Department of Health Services
AWQC—Ambient Water Quality Criteria
MCL Maximum Contaminant Level
MCLG—Maximum Contaminant Level Goal
SDWA—Safe Drinking Water Act
DW—Drinking Water
Sources: U.S. EPA 1986. Public Health Assessment Manual
ADHS 1987. S. Eberhart
RD/R56/057-3
-------
DESCRIPTION.
The selected alternatives for the Section 16 Operable Unit
are:
o Groundwater
Water from Subunit A will be drawn from the entire
Section 16 area until contaminant levels are
reduced to meet ARARs, and the water treated to
meet ARARs. Water from Subunit B/C will continue
to be pumped by Loral Corporation and the
Phoenix-Goodyear Airport and closely monitored.
Currently, GAC-2 is pumped about 50 percent of the
time at 1,000 gpm during the irrigation season and
about 15 percent of the time during the winter.
GAC-3 is used for standby fire protection and not
normally pumped. GAC-4 has very little usage.
PLA-2 is pumped for 2 to 3 hours per day at a rate
of about 450 gpm. Pumping from those wells may be
altered to optimize plume containment and removal.
o Treatment
Air stripping towers will be used to remove the
VOC's from the groundwater. Emission controls
such as activated carbon units will be used to
treat the air effluent.
. Contaminated water will be pumped out of the
ground and routed via pipelines to the treatment
plant. There the water will be sprayed down as
air is pumped up a packed column to remove VOC's.
Air flowrate, column diameter/ and packing depth
will be designed based on maximum contaminant
levels and organic volatilities. Stripped water
will then be reinjected into the aquifer at a loca-
tion that will not adversely affect the groundwater
flow to the supply wells, or adversely affect con-
taminant flow in the groundwater system.
Air containing the stripped organics will be treated
in a bed of granular activated carbon to reduce
air emissions. When the carbon becomes saturated
with organics, it will require regeneration or
proper disposal. At other sites, this has typi-
cally been done once or twice a year.
End Use
Reinjection is the preferred end use for the water
from Subunit A.
RD/R52/024 VI-3
-------
It is expected that treatment facilities for Subunit A will
be in operation for a period of 82 years.
Additional study is required to determine if further water
treatment is necessary to prevent scaling and biological
growth in the air strippers, the proper location of the
reinjection wells.
By capturing the contaminant plume in Section 16, this
selected remedy will accomplish the objective of the Sec-
tion 16 Operable Unit, which is to stop migration of con-
taminants beyond Section 16 in Subunit A and from entering
Subunit B/C. It will reduce further deterioration of the
aquifer outside of Section 16 and reduce the volume and
toxicity of the contamination in Section 16. It also ful-
fills the statutory preference for permanent solutions at
Superfund sites.
The .selected remedy, as proposed, will meet all enforceable
federal and state requirements for water quality. The result-
ing saturated carbon from the air emission control equipment
will either be regenerated or disposed of in a safe manner
at an approved RCRA facility.
RD/R52/024
RD/R52/024 VI-4
-------
Appendix A
INDEX OF ADMINISTRATIVE RECORD
Date of
Publication
June, 198'4- Ecology and Environment, Inc. Final Workplan
RI/FS Litchfield Airport Area. Goodyear,
Arizona. June 1984.
Describes the activities to be carried
out and the methodology for the remedial
investigation and feasibility study of
the Litchfield Airport Area (later
renamed the Phoenix-Goodyear Airport).
July, 1984 Ecology and Environment, Inc. Draft
Community Well Sampling Plan. Phoenix-
Litchfield Airport Area Remedial Investiga-
tion. July 2, 1984.
Specifies the procedures and activities
for taking water samples from wells in
the area of the Phoenix-Litchfield
Airport. Done as a part of the RI.
July, 1984 Ecology and Environment, Inc. Draft Sampling
Plan Phase I Drilling, Well Installation and
Aquifer Testing. Phoenix-Litchfield Airport
Area Remedial Investigation. July 2, 1984.
Specifies the procedures and activities
for installing new wells and taking
water samples from those wells.
Aug., 1984 Engineering-Science, Inc. Contamination
Assessment Plan. August 1984.
Provides revised plan for assessment of
groundwater contamination in the vicin-
ity of the Goodyear Aerospace Corpora-
tion facility (currently owned by Loral
Corporation). This was done as a
requirement of Administrative Order
84-02 issued by EPA, Region IX.
Oct., 1984 CH2M HILL. Final Community Relations Plan.
Phoenix-Litchfield Airport Area.October
1984.
Prepared as part of Phase 1 of the RI/FS
to provide a means of gathering back-
ground, site history/ and a discussion
of the concerns of interested parties.
RD/R94/029 A-l
-------
Date .of
Publication
Nov., 1984
Aug., 1985
Oct., 1985
Jan., 1986
Jan., 1986
Ecology and Environment, Inc. Quality
Assurance Project Plan. Indian Bend Wash and
Phoenix-Litchfield Airport Area Sites.
November 1984.
Describes procedures for ensuring qual-
ity control and reliability of sampling
procedures, field measurements, equip-
ment maintenance, analytical procedures,
data management, and document control.
Engineering-Science, Inc. Remedial
Investigation Phase I Results Contamination
Assessment Report. Prepared for Goodyear
Aerospace Corporation. Litchfield Park,
Arizona. August 1985.
Presents the results of Phase 1 drilling
and depth-specific monitoring well
installation conducted by Goodyear
Aerospace Corporation as specified in
the Contamination Assessment Plan,
August 1984.
Jacobs Engineering, Inc. Phoenix-Litchfield
Airport Area Responsible Party Search Title
Search. Final Assessment. October 25, 1985.
Presents findings of investigation for
site history and chronology of signifi-
cant events regarding hazardous mate-
rial, interviews with the industry and
public witnesses, and a financial
assessment of the PRP's.
Ecology and Environment, Inc. Task 5.3 Phase
I Data Summary/Report. Phoenix-Litchfield
Airport Area Remedial Investigation.
2 Volumes. January 17, 1986.
Presents data regarding aquifers, soil
materials, and contamination beneath the
PGA area.
Ecology and Environment, Inc. Task 4.0
Source Verification, Field Investigation.
Phoenix-Litchfield Airport Area Remedial
Investigation. 2 Volumes. January 31, 1986.
RD/R94/029
A-2
-------
Date of
Publication
Provides a history of hazardous waste
disposal practices, assessment of known
and suspected contaminant source areas,
and a determination of other potential
sources.
Apr., 1986 Ecology and Environment, Inc. PLA Sampling
Plan. March 19, 1986.
Provides objectives, methods, and
procedures for semiannual well water
sampling and analysis. Sampling was
done in April 1986.
Oct., 1986 CH2M HILL. Technical Memorandum; Results of
Soil Gas Sampling and Analysis.Phoenix-
Litchfield Airport Remedial Investigation
Phase II, Stage 1. October 3, 1986.
Discusses soil gas sampling and mobile
analysis conducted at the PGA superfund
site from July 17 to 25, 1985.
*
Dec., 1986 CH2M HILL. Evaluation of Potential Water Use
Alternatives"Phoenix-Goodyear Airport
Remedial Investigation Phase II, Stage 1.
December 1, 1986.
Presents an evaluation of potential
water user alternatives near the
Unidynamics site. Also applies to
Section 16 because of its proximity.
Dec., 1986 U.S. Environmental Protection Agency.
Interim Guidance on Superfund Selection of
Remedy'. December 24, 1986.
Provides new guidance on the selection
of remedial actions in the absence of a
new edition of the NCP. Incorporates
Superfund Amendments and Reauthorization
Act of 1986 (SARA).
Feb., 1987 CH2M HILL. Soil Gas Technical Memorandum
RI/FS. Phoenix-Goodyear Airport.
February 27, 1987.
Discusses soil gas sampling and mobile
analysis conducted at the PGA superfund
site from January 3 to 22, 1987.
RD/R94/029 A-3
-------
Date of
Publication
Mar., 1987
Apr., 1987
Apr., 1987
May, 1987
June, 1987
July, 1987
CH2M HILL. Draft Work Plan Operable Unit
Feasibility Study for Section 16 of
Phoenix-Goodyear Airport Site. March 1987.
Defines activities to be carried out to
conduct an operable unit feasibility
study for Section 16 of the PGA site.
CH2M HILL. Technical Memorandum;
Groundwater Extraction Alternatives for
Section 16 of Township 1 North, Range 1 West.
Phoenix-Goodyear Airport RI/FS.April 8,
1987.
Provides preliminary estimate of ground-
water extraction rates and well loca-
tions necessary to control migration of
contamination within Section 16 of the
PGA site.
CH2M HILL. Draft Preliminary Public Health
Endangerment Assessment. Phoenix-Goodyear
Airport Superfund Site. 2 Volumes.
April 10, 1987.
Provides an assessment of risk of public
health and the environment associated
with the PGA site.
Letter from Lee Thomas, Administrator,
U.S. EPA, to Honorable James J. Florio.
May 21, 1987.
Discusses the uses of maximum
contaminant levels versus maximum
contaminant level goals.
CH2M HILL. Public Comment Feasibility Study
for Section 16 Operable Unit. Goodyear,
Arizona.June 1987.
Discusses and screens remedial actions
for providing an expedited cleanup of
the Section 16 Operable Unit.
U.S. Environmental Protection Agency.
Interim Guidelines on Compliance with
Applicable or Relevant and Appropriate
Requirements. July 9, 1987.
RD/R94/029
A-4
-------
Date of
Publication
Provides new guidance on selection of
ARAR's and MCL's as cleanup standards
for Superfund sites. Incorporates SARA.
Currently being CH2M HILL. Technical Data Management II
updated computerized data base located in CH2M
HILL's Phoenix and Redding offices.
Contains all water elevation and quality
data from ADHS, responsible parties and
EPA sampling. (1981-present)
RD/R94/029
RD/R94/029 A-5
-------
Appendix B
RESPONSIVENESS SUMMARY
PHOENIX-GOODYEAR AIRPORT
SECTION 16 OUFS
OVERVIEW
During the public comment period for the Public Comment
Operable Unit Feasibility Study from June 2 through July 2,
1987, EPA received comments on the recommended remedy for
the cleanup of Section 16 of the Phoenix-Goodyear Airport
site. Comments were received from persons residing or doing
business in that area.
Most of the comments were of an editorial nature or
addressed issues that are not fundamental to EPA's selection
of a remedial action; however, the OUFS will be reissued to
reflect all comments noted, and the remedial design will
respond to comments as a part of this record of decision.
This responsiveness summary reflects the changes made in tiie
OUFS as a result of comments received and indicates where
those changes were made.
One issue that is fundamental to the selected alternative is
the appropriateness of pumping aquifers in Subunit B/C at
greater than current rates while still gathering information
on these subunits. It has been decided to not expand the
pumping in Subunit B/C until additional data pertaining to
the aquifers and contaminants in this Subunit become avail-
able, and an alternative selection can be reevaluated during
the final remedy. Final selection, including extraction and
injection well placement and pumping rates for Subunit A,
will be determined during the remedial design period.
SUMMARY OF PUBLIC COMMENTS AND AGENCY RESPONSES
FROM PAMELA SWIFT, TOXIC WASTE INVESTIGATIVE GROUP
1. Question/Comment: I want to see some health studies
done in this area. Response; As part of the overall remed-
ial investigation/feasibility study (RI/FS) an endangerment
assessment (EA) will be conducted. The EA will consist of a
public health evaluation and environmental assessment. The
Agency for Toxic Substances and Disease Registry will review
the EA as well as conduct a health impact study prior to
signing of the final record of decision, which is planned
for summer 1988. See page 3-21 of OUFS.
RD/R9/018 B-l
-------
FROM SUNCOR DEVELOPMENT COMPANY
1. Question/Comment; We have a need for irrigation water
for our farm crops and would like to use the treated ground-
water if it becomes available for irrigation purposes.
Response; Reinjection is the selected alternative for
Subunit A water because of the high IDS levels that make
this water unsuitable for irrigation. See pages 5-6 and
8-12 of OUFS.
FROM CRANE, UNIDYNAMICS
1. Question/Comment; Consideration should be given to the
possibility of conveying water pumped from wells in the
Unidynamics area to the OU for treatment and subsequent
end-use, precluding the need for a separate treatment
facility in the Unidynamics area. Response; The overall
RI/FS will consider this configuration. The treatment plant
will be designed in a modular fashion to allow expansion for
increased capacity.
2. Question/Comment; Hydraulic connection of Subunits B
and C pertain only to the PGA area. A good hydraulic
connection between the two units has not been shown in the
Unidynamics area. Response; See pages ES-1 and 2-1 of
OUFS. •
3. Question/Comment; The public health evaluation pertains
to the entire Superfund study area, including PGA, GAC, and
Unidynamics. Should it be modified to address only PGA and
GAC for this document? Response; The public health evalua-
tion portion of the OUFS, Chapter 3, was modified to address
only PGA and GAC. See Chapter 3 of OUFS.
4. Question/Comment; Where appropriate, text and figures
should be modified to reflect the purchase of Goodyear-
Westinghouse property by SunCor. Response; See Chapter 2
of OUFS.
5. Question/Comment; On Figure ES-2, steam stripping is
indicated under water treatment alternatives but is not
addressed in the text. Response; Steam stripping is
addressed in Table 7-2. See Table 7-2 of OUFS.
6. Question/Comment; On page 1-1, 5th paragraph, 1st sen-
tence, it may be more appropriate to say "... acceptable
level of contaminants in Arizona ground water." Response;
See page 1-1 of OUFS.
7. Question/Comment; On page 1-1, 5th paragraph, 4th
sentence, refer to treatment levels in aquifer and extracted
water. Response; See page 1-1 of OUFS.
RD/R9/018 B-2
-------
8. Question/Comment; By page 1-3, the PGA and Unidynamics
areas have not been defined. A map prior to this may help
clarify. Response; See Figure 1-1 of OUFS.
9. Question/Comment; Are the estimated contaminant concen-
trations presented on Figures 2-3 and 2-4 mode, mean, or
median values? Response; See Figures 2-1 and 2-2 of OUFS.
10. Question/Comment; PLA is used to designate wells.
Should it be said that PLA = PGA? Response; Although the
airport name has been changed, the well designations have
not been changed.
11. Question/Comment; Is TDS concentration of 3,900 ppm in
Subunit A an average for all measurements? Response; Yes.
See page 3-2 of OUFS.
12. Question/Comment; Unidynamics does not, and never has
had, a separate production well for its water supply. The
City of Goodyear has always provided water to the facility.
Response; See Chapter 2 of OUFS.
13. Question/Comment; For comparison purposes, it would be
easier if the zip patterns in the legends of Figures 3-1 and
3-2 were consistent. Response; See Figures 3-1 and 3-2 of
OUFS.
14. Question/Comment; On page 5-2, various alternatives
could be linked more directly to Figure 5-1 by labeling each
bullet with abbreviations from Figure 5-1, such as GAG, GAC
& PGA, Section 16, etc. Response: See page 5-2 of OUFS.
15. Question/Comment; On Figure 5-1, steam stripping is
listed but never discussed in the text of that section.
Response; Steam stripping is discussed in Table 7-2. None
of the screened out alternatives are discussed in the text.
See Table 7-2 of OUFS.
16. Question/Comment; On page 5-5, what is Storm
Treatment? Response; A typographical error—should have
been Steam Treatment. See page 5-5 of OUFS.
17. Question/Comment; On page 7-17, line 18, "backing"
should be packing. Response; See page 7-17 of OUFS.
18. Question/Comment; On page 7-26, under General Assump-
tions, will monitoring wells, as well as influent and efflu-
ent wells, be sampled for analysis on a weekly basis?
Response; This frequency was used as a cost basis. The
actual sampling frequency will be determined during the
remedial design phase.
RD/R9/018 B-3
-------
FROM EPA, AIR TOXICS OFFICE, AMD
1. Question/Comment; We recommend that you consider sev-
eral design and operating factors for the stripping towers
during the design stage of the project. Response; The
design and operation factors have been received from your
office and will be considered during design.
2. Question/Comment; Although ambient air concentrations
in the vicinity of the stripping tower would be expected to
be low, you may want to consider some initial ambient air
monitoring. This has been performed at other Superfund
sites to demonstrate to interested parties that concentra-
tions are in fact as low as expected. Response; Air
sampling will be added to OU operations.
FROM U.S. ARMY CORPS OF ENGINEERS, OMAHA DISTRICT
1. Question/Comment; Subunit B/C should be evaluated more
carefully in light of recent and forthcoming data. Reinjec-
tion of treated effluent for plume control should be care-
fully evaluated and considered. A technical memo outlining
new information would be helpful in making decisions con-
cerning remediation of Subunit B/C. Response? The OUFS
stage is considered to be a 10-percent design. It is con-
ducted to compare several alternatives that can provide an-
expeditious response to the contamination hazard while not
being inconsistent with the final remedy. Deep wells being
installed at this time will provide additional data to be
incorporated into the design. It has been determined that
the best approach to Subunit B/C is to allow Loral Corp-
oration and the airport to continue pumping as they cur-
rently do, and conduct an extensive groundwater monitoring
program.
2. Question/Comment; Information available at the time
this OUFS was prepared does not adequately define the con-
taminant plume and is insufficient to design an extraction
scheme. Work in progress may be sufficient; however, addi-
tional work may be required during the design phase. Bench
and/or pilot scale treatability testing will be necessary to
properly design the proposed treatment system. Response;
Comment will be noted in final OUFS. Bench and/or pilot
scale testing is planned for final design of the air
stripping process.
3. Question/Comment; On page ES-1, the word "minor" in
sentence "Other VOC's have been identified sporadically and
in minor concentrations..." is misleading as it seems to
indicate that these levels are inconsequential when in fact
some exceed regulatory standards. See Chapter 3, Table 3-2.
Response; See page ES-1 of OUFS.
RD/R9/018 B-4
-------
4. Question/Comment; On page ES-2, 8th bullet, clarify
that this refers to treated groundwater. Response; See
page ES-2 of OUFS.
5. Question/Comment; On page ES-5, the definition given
for rehabilitation is inaccurate. Response; See page ES-5
of OUFS.
6. Question/Comment; On pages ES-5 and 6, rehabilitation
and level of treatment seem redundant. Clarify the distinc-
tion between these two. Response; Rehabilitation refers to
aquifer treatment. Level of treatment under Treatment
Alternatives refers to treatment of extracted groundwater.
7. Question/Comment; On page 2-1, 4th paragraph, clarify
that Unit A should be Subunit A. Response; See page 2-1 of
OUFS.
8. Question/Comment; On page 2-1, 4th paragraph, you say,
historically, groundwater flow direction under Section 16 is
to the southwest. However, flow has been more westerly than
southwesterly in the UAU. Clarify. Response; There are
not enough data to conclusively state whether the flow is
more southwesterly or west by southwesterly due to
occasional fluctuations. .
9. Question/Comment; On page 2-2 there is reference to PGA
well No. 3 as having the highest level of TCE. The location
of this well should be indicated on appropriate drawings.
Response; The well location is indicated as PLA3 on
Figure 2-3.
10. Question/Comment; Clarify what contaminant concentra-
tions represent in Figures 2-2 and 2-3. Response; They
represent single event values.
11. Question/Comment; The historical waste disposal prac-
tices section does not provide a comprehensive understanding
of past chemical use and disposal practices. More investi-
gations should provide a clearer picture; however, a detailed
and quantitative determination will probably not be possible.
The information presented in this report has been compiled
from many sources and may be accurate for certain periods of
operations only. The nature of the information—verified
from more than one source, secondary, etc.—should be
identified. Response; Comment will be noted in final OUFS.
EPA is continuing to try to determine the history and
source(s) of contaminants at the site.
12. Question/Comment; Re page 2-9, 1st paragraph, avail-
able information indicates that most of the Goodyear facil-
ity was owned by Southwest Cotton Company/Goodyear Tire/
RD/R9/018 B-5
-------
Aircraft. Several small parcels, which apparently consisted
of a portion of the building referred to as Building/ Hangar
6 and several very small areas, were purchased by the Gov-
ernment in 1943. A greater portion of the Goodyear facility
was purchased by the Government in 1947. The entire "plant"
area (present facility) was quitclaimed to Goodyear Aircraft
in 1950. Response; See page 2-7 of OUFS.
13. Question/Comment; Re page 2-11-14,, it should-'be clari-
fied that the entire aircraft was usually not covered with
the protective coating, only key sections of the aircraft
that would be prone to moisture-induced corrosion s.a. open-
ings, fabric surfaces, etc. Stripping consisted of peeling
of the coatings manually and not by use of chemical
strippers, except for early coatings on windows which were
removed with ammonia or alcohol. Latex materials were used
in protective coatings for some portion of the total time of
operations. Coatings used included "liquid envelope" and
later "spraylat."
"Gunk" was not used in stripping of protective coatings and
was probably used more extensively for engine degreasing or
to degrease metal surfaces prior to preservation, again a
limited portion of the airplane. Also note that many air-
planes stored were fabric and dope structure.
4
While the Airport property was transferred to the City of
Phoenix in 1968, Navy operations ceased prior to 1 July 1967
Response; See pages 2-9 through 2-14 of OUFS.
14. Question/Comment; Re page 2-14, more recently acquired
information indicates that most drums and other chemical
containers were returned to suppliers for reuse and that
little if any local disposal of containers occurred.
Response; See page 2-12 of OUFS.
15. Question/Comment; Re page 2-15, drawings ("as-built")
on file with the City of Phoenix should be consulted for
details on the washrack and drainage system design and con-
struction and these discussions corrected/clarified appropri-
ately. The washracks still exist, much as constructed.
Response: See page 2-13 of OUFS.
16. Question/Comment; Re page 2-15, describe sources of
information on historical activities, such as statement con-
cerning air flotation not being used. Was source directly
involved with treatment plant operation, i.e., did source
have direct knowledge? Response; Historical information
came from the Source Verification Report, Ecology and
Environment, Inc. January 1986. See page 2-13 of OUFS.
RD/R9/018 B-6
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17. Question/Comment; Re Table 2-4, it should be made
clear that this table does not indicate either relative or
absolute amounts of chemicals used. Response; Unnecessary
due to no mention of amounts.
18. Question/Comment; Re page 5-2, for clarity, the ini-
tial paragraph under GROUNDWATER ALTERNATIVES should include
pumping as well as no-action and containment, then the pump-
ing alternatives detailed. Response; See page 5-2 of OUFS.
19. Question/Comment; . Re page 5-2, area NW of runway
should be excluded for pumping Subunit B/C based on no
concentrations reported above 1 ppb in that area. Response;
The decision to include this area was not based on data, but
on suspected contamination. New data will provide an
opportunity for reevaluation.
20. Question/Comment; Re Chapter 6, information available
at the time this OUFS was prepared does not adequately
define the contaminant plume and is insufficient to design
an extraction scheme. Work in progress may be sufficient or
additional work may be needed during the design phase.
Response: See previous response.
21. Question/Comment; Re page 6-1, monitoring is usually,
considered part of the no-action alternative. Response; '
See page 6-1 of OUFS.
22. Question/Comment; Re page 6-3, a discussion of prob-
able molecular diffusion rates into "dead" zones is needed.
These areas would be subject to reverse gradients as cleanup
continues. Since it is unlikely that significant volumes of
contaminant would be tied up in these zones, this is a super-
fluous discussion. Sorbed contaminant soil particles in
dewatered zones is of greater concern. Response: The diffu-
sion of contaminants into low permeability units can be an
important process. Such units can act as long-term sources
for contaminants, thus delaying total cleanup. See, for
example, Gilliam, et al, (1984), An Advection-diffusion
Concept for Source Transport in Heterogeneous Unconsolidated
Geological Deposits, Water Resources Research, Vol. 20, No. 3,
pp. 369-378. As noted, sorbed (or otherwise slowly mobile
chemicals) in the vadose zone can be another long-term source
of contaminants. See page 6-3 of OUFS.
23. Question/Comment: Re Table 6-2, the choice of 10 pore
volumes for extended cleanup gives an unrealistically
conservative estimate of cleanup time. Note difference
between values given on page 9-7 and Table 6-2. Response;
The time required for cleanup is not known. For the
purposes of comparing alternatives, five pore-volumes were
used.
RD/R9/018 B-7
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24. Question/Comment; Re Figure 6-4, it is evident that
capture zones greatly exceed the targeted cleanup area under
this alternative. Note "stagnant" zones near divides
between cones - the "accelerated" nature is not apparent.
Response; This alternative was presented to provide a wide
choice of cleanup. Appropriate capture zones will be
developed during the remedial design activities.
25. Question/Comment; Re Figure 6-6, 7, 8, these scenarios
should be reconsidered in view of more recent monitoring
well data. Response; All pumping alternatives will be reeval-
uated with new data during design.
26. Question/Comment; Re page 6-21, it is not clear if the
combined effect of contaminated groundwater withdrawal and
normal seasonal pumping will impact nearby wells. Please
clarify. Response; There is no seasonal pumping of
Subunit A. Water levels in Subunit A will be maintained in
accordance with remedial design parameters. See page 6-21
of OUFS.
27. Question/Comment; Re page 6-22, it is not clear if
declines in Subunit A water levels (because of the proposed
extraction of contaminated water) has been considered in
estimating transmissivity for the subunit and hence for per-
formance of the extraction wells. (Efficiency is reduced as
drawdown occurs.) Please clarify. Response: Drawdown
effects were considered. A typical guideline of maintaining
drawdown in the pumping well at less than two-thirds of the
available drawdown was followed. Drawdown in most of the
Subunit A zone is expected to be less than 20 percent of the
saturated thickness. See page 6-22 of OUFS.
28. Question/Comment; Re page 6-24, for the monitoring
wells, it was assumed that three per extraction well was
sufficient. This was apparently applied across the site
regardless of location. In areas of numerous existing wells
or densely spaced extraction wells, this number of new wells
may not be necessary. More detailed analyses should be per-
formed for actual numbers of monitoring wells needed.
Response: Three wells were chosen for cost estimating pur-
poses. A more detailed analysis will be done during design.
29. Question/Comment: Re page 7-7, the OOFS should include
an expanded discussion concerning the necessity of pilot
testing. Pilot testing could determine pretreatment require-
ments (due to high TDS and sulfide levels), evaluate or con-
firm the mass transfer efficiency of a particular packing,
verify removal efficiency, verify mathematical model, clar-
ify off-gas pretreatment requirements and design parameters,
possible scaling problems, anti-scaling problem design con-
siderations, etc. Response: Bench testing will be con-
ducted during design.
RD/R9/018 B-8
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30. Question/Comment; Re page 7-16, chemical feed system
design and potential problems associated with scaling need
to be addressed. This is particularly important with the
high concentrations of TDS and sulfate in Subunit A. With
the high concentrations of sulfate, there is a good possi-
bility of a manganese sulfide precipitation, this would
probably require removing the filter media for cleaning of
the precipitate. An estimate on the frequency and approxi-
mate down time in the system operation should be analyzed.
These factors should be addressed briefly in the OUFS and in
detail during pre-design and design. Response; Research on
this factor is currently being done by GAG. This will be
addressed in detail during predesign and design.
31. Question/Comment; Re page 7-16, onsite versus offsite
cost comparisons should be analyzed for carbon regeneration.
Has ttie cost of an onsite or the operational cost of offsite
carbon regeneration been incorporated into the estimate?
Response; Onsite regeneration is part of the carbon adsorp5-
tion alternative. The onsite costs included significant
fluctuations as to overlap costs for offsite regeneration.
32. Question/Comment; Re page 7-17, indicate how/where the
disposed scale cleaning solution could be disposed of and
the cost associated with that disposal. Response; See pre-
vious response. •
33._ Question/Comment; Re page 7-17, has the impact
(environmental and O&M considerations) of an influent pipe
rupture been considered? Response: A detailed risk assess-
ment will be conducted during design.
34. Question/Comment; Re page 7-18, carbon usage could be
evaluated in pilot study. Response; It will be.
35. Question/Comment; Re page 7-27, the impact of the high
TDS on treatment should be addressed in more detail. Impact
(including impact on costs) could be significant. See also
comments on pages 7-16 and 7-17. Response: See response to
those comments.
36. Question/Comment; Re Chapter 8, address the advantages
and disadvantages with combining the treatment and collec-
tion lines in the preferred alternatives. Also indicate the
cost benefits that would be obtained by combining the treat-
ment for Subunit A and B/C. It seems that if the treatments
proposed are similar or identical that they could be com-
bined. Response; A detailed analysis will be conducted
during design. Alternatives for Subunit B/C are not
included in this remedy.
37. Question/Comment; Re Chapter 8, a discussion of the
potential use of reinjection for plume control should be
RD/R9/018 B-9
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included. Effluent piping costs would decrease as may over-
all treatment costs/time. This must be addressed—if not ir
the OUFS, then in the OU predesign phase. Response; see
page 8-15 of OUFS.
38. Question/Comment; Re page 8-5, include, if available,
the water quality in Subunit B/C. This information will be
helpful in determining water quality of the influent to the
air stripper. Response; See Table 8-2 of OUFS.
39. Question/Comment; Address items which should/could be
considered for implementation/construction with the OU
facilities which would facilitate implementation of the
final remedy—s.a. to lay additional piping, providing space
for additional stripping towers, etc. Response; A detailed
analysis will be conducted during design.
40. Question/Comment; Re page 9-13, reinjection wells will
undoubtedly need rehabilitation and/or replacement. (Cost
estimates should reflect this.) Response; This will be
addressed during predesign and design.
41. Question/Comment; There is no discussion of the fine
tuning of the design through testing during the construction
phase and use of wells during the startup and operation
phases. This need not be addressed in detail at this point
but should be addressed during the subsequent project
phases. Response; This will be addressed during predesign
and design.
FROM ARIZONA DEPARTMENT OF WATER RESOURCES
1. Question/Comment: The Middle Fine-Grained Unit at the
site is actually 800 to 1,000 feet thick at the site, and
the Lower Conglomerate Unit is thicker than 1,000 feet.
Response; See pages ES-1 and 2-1 of OUFS.
2. Question/Comment; The PLA well No. 3 is also referred
to as the PGA well No. 3. This is inconsistent. Response;
The well designations have never been changed. The correct
designation is PLA well No. 3.
3. Question/Commentt There should be some mention of the
recent purchase of the Goodyear Aerospace Corp. facility at
the site by the Loral Corporation. Response: See page 2-9
of OUFS.
4. Question/Comment: Regarding current conditions and land
use, agricultural land use would seem to be more related to
industrial-based mixed use than recreational-based mixed
use. Response; See page 3-4 of OUFS.
RD/R9/018 B-10
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5. Question/Comment; General response actions and tech-
nologies: Justification for applicable response actions
should make some statement to the effect that there are •
technologies which have been proven to be effective in -the
past. Also', rejection of in situ treatment should state
that the time required to effect cleanup is excessive.
Response; See Table 4-2 and Chapter 7 of OUFS.
6. Question/Comment; The Arizona Department of Water
Resources has jurisdiction over contamination problems and
the proposed remedial alternatives impacting the ongoing
water conservation efforts within the Phoenix Active
Management Area. Response; See page 6-1 of OUFS.
7. Question/Comment; Regarding RESSQ modeling, a statement
should be made to the effect that, due to the uncertainties
inherent in the RESSQ model, final remedial alternatives
will be determined with the results of the numerical
modeling efforts currently underway. Response; Remedial
alternatives will be addressed in detail during the remedial
design period, including placement of wells and pumping
rates. This will take into account all new data and models
which are available. See page 6-4 of OUFS.
8. Question/Comment; On page 9-1 under PUMPING; suggest
replacing the word "significantly" with "sufficiently."
Response; See page 9-1 of OUFS.
FROM GOODYEAR TIRE AND RUBBER COMPANY
1. Question/Comment; The Goodyear Tire and Rubber Company
submitted its comments in the form of a preferred alterna-
tive report. Their preferred alternative is to treat all
groundwater in Subunit A in Section 16 using air stripping;
however, they have offered an alternate scheme for extrac-
tion and reinjection. This alternative includes five
extraction wells and nine injection wells. The injection
wells would serve to recharge the aquifers of Subunit A and
to provide contaminant plume control to force contaminants
towards the extraction wells. Response; The use of injec-
tion wells to enhance plume recovery is not justified under
the current state of knowledge at the site. Injection wells
will cause an increase in the hydraulic gradient downward to
Subunit B/C in the vicinity of the wells. High permeability
conduits or holes in the aquitards could cause contaminants
to move into presently uncontaminated areas as a result of
injection. In addition, the proposed location of the
injection wells is actually within the contaminated plume.
Reinjection into contaminated groundwater will enhance the
rate of spreading of contamination both laterally and
vertically. In view of this, injection wells should be
rejected at the present time for the purpose of plume
RD/R9/018 B-ll
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control. Additional information may become available to
warrant consideration of injection wells at the time of
final remedy selection.
The' drawdown of groundwater levels and the pumping water
levels in the wells apparently have not been calculated.
This is an important consideration in designing the extrac-
tion well field.
2. Question/Comment; Goodyear also recommends that EPA
delay pumping and treating Subunit B/C groundwater for the
following four reasons:
(1) The remedial investigation to define the areal
extent of contamination in Subunit B/C is still
ongoing. The outstanding data are essential for
selecting the optimal location of Subunit B/C
groundwater recovery wells and evaluating treat-
ment alternatives. Response; EPA intends to make
a final selection for remedial action in
Subunit B/C when additional data are available.
(2) Subunit B/C groundwater is pumped continuously for
use by the Loral Corporation and the Phoenix-
Goodyear Airport as process and drinking water.
The extraction, combined with pumping Subunit A •
groundwater to prevent migration of contaminants,
will slow or stop contaminant migration and pro-
vide some measure of cleanup to Subunit B/C ground
water. As shown by EPA in Table 6-5 of the "Public
Comment Feasibility Study," Subunit A groundwater
contains 95 percent of the TCE contamination in
the Upper Alluvial Unit. Response; The current
extraction of groundwater may or may not prevent
contaminant migration. Additional monitoring wells
are necessary to determine the hydraulic effect of
the existing and future wells.
(3) Adverse health effects from postponing extensive
treatment of Subunit B/C groundwater will be negli-
gible. Recently acquired data suggest that con-
tamination in Subunit B/C is in the immediate
vicinity of production wells on Loral and airport
properties. The affected population is supplied
with treated or carefully monitored drinking water
to protect human health. EPA's Public Comment
Feasibility Study states on page 3-3: "West of the
City of Goodyear, most of the land is currently
used for agricultural production. Some smaller
areas of residential development exist outside of
Goodyear, but these are several miles to the west
of the city." Growth of the city is expected to
be to the west. If the City of Goodyear expands
RD/R9/018 B-12
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its extraction network in light of the projected
population increase, the new wells are not likely
to exhibit contamination, nor are they likely to
become contaminated since pumping of Subunit A
groundwater will halt any migration of contaminants.
Response; There is no proof that new wells to the
west are not likely to be contaminated. The area
downgradient of the site will need to be monitored
on a long-term basis to ensure that contaminated
groundwater is not being pumped and delivered to a
municipal or private system.
(4) There is a technical advantage to delaying extrac-
tion of Subunit B/C groundwater. The different
aquifer characteristics of Subunits A and B/C indi-
cate that the water level in Subunit B/C will drop
much faster than that of Subunit A if the two are
pumped simultaneously. Under such conditions, the
potential for downward migration of contaminants
will greatly increase. Pumping Subunit A alone
for a period of time will lower the Subunit A watex
level and alleviate possible problems if a decision
is made to increase pumping from Subunit B/C.
Response; Although the comment is strictly true,
the fact that a vertical downward gradient has
existed for many years at the site suggest that
there is little advantage in delaying additional
installation of wells and pumping of the B and C
subunits.
3. Question/Comment; On page 2-10 of the "Public Comment
Feasibility Study for Section 16 Operable Unit, dated June
1987, the text reads: "Only one of the six is currently
being used as a source of drinking water, and GAC, the
owner, is providing bottled water as an alternative." GAC
(Goodyear Aerospace Corporation) did offer bottled water at
its facility when groundwater contamination was first dis-
covered, but has since installed a carbon adsorption/reverse
osmosis treatment system to produce safe drinking water.
Response: See page 2-5 of OUFS.
4. Question/Comment: On page 2-10, Table 2-2 estimates
that GAC disposed of 31,000 gallons of halogenated and non-
halogenated solvents between 1949 and 1974. The only docu-
mented onsite disposal of solvents (not necessarily TCE) by
GAC was a small volume placed in a lined drying bed in 1971.
Because there is no sound basis for the total quantity of
31,000 gallons for the corresponding time period, Goodyear
requests that the value be omitted. In addition, the foot-
note "a" is inappropriate for the 4,900 gallons specified
for 1,1,1-trichloroethane. That volume is a documented,
RD/R9/018 B-13
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offsite disposal quantity, not an approximation. Response;
Volumes generated by disposal practices are currently being
investigated. See Table 2-2 of OUFS.
5. Question/Comment; It should be noted on Table 2-2 that
the 12 tons of chromate sludge placed in onsite disposal
pits contained relatively nontoxic, immobile trivalent chro-
mium and- not hexavalent chromium. Also, when the pits were
closed in 1980, a total 383 tons of soil, sludge, and fabric
liner were excavated and transported to an offsite disposal
facility. Response: Volumes have been removed from
Table 2-2.
6. Question/Comment; Figure 2-4 on page 2-12 contains some
errors and omissions in locations of legend numbers. The
plant powerhouse, Circle 24, is actually adjacent to
Building 16, Circle 5. The 1,1,1-trichloroethane storage
tank, Circle 25, belongs in the northwest corner of
Buildings 1 and 2. Circle 19 is missing from the parking
lot east of Litchfield Road.
Table 2-3, the legend to Figure 2-4, also requires some cor-
rection. Items 2 and 3, Buildings 1 and 2, are currently
mostly manufacturing, not offices as stated. Item 6, Build-
ing 76, was built in the 1940's, not in 1976. Item 7,
Building 70, formerly was used for shipping and receiving '
but currently is used as storage space. Item 8 used to be a
general storage building and now serves as office space; it
was never used for virgin chemical storage. Item 10 is the
virgin chemical storage building. Item 11, Building 50, was
constructed in the 1980's and not the 1960's.
Response: See Figure 2-3 and Table 2-3 of OUFS.
FROM EPA, REGIONAL ADMINISTRATOR'S OFFICE
1. Question/Commentt Several of the proposed maximum con-
taminant levels are now Safe Drinking Water Act maximum con-
taminant levels. Proposed drinking water treatment levels
have been changed-to reflect those levels. Also, EPA has
issued a health advisory that chloroform should not exceed
0.5 parts per billion in drinking water. Drinking water
standards exceed Ambient Water Quality Criteria. Response:
The new material has been received and will be incorporated.
See Table ES-1 of OUFS.
2. Question/Comment: In the section that identifies ARARs,
there should be consideration given to other criteria and
health advisories. Response: See page 1-1 of OUFS.
3. Question/Comment; On Table 3-3, there needs to be a
total cancer risk assessment for all chemicals identified.
RD/R9/018 B-14
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Why is Unidynamics mentioned? 1,1-DCE is not a carcinogen.
Response; See Table 7-3 of OUFS.
FROM EPA, OFFICE REGIONAL COUNSEL
1. Question/Comment; Shouldn't containment technology be
included in the surviving technologies? Response: Yes,
this technology will be added. See Chapter 9 of OUFS.
2. Question/Comment; Is the DCE target level accurate?
The arsenic treatment target level does not comply with
AWQC. Response; The target level for DCE has beed changed
to reflect the new SDWA maximum contaminant levels. Arsenic
will be addressed in the overall feasibility study. See
Table ES-1 of OUFS.
3. Question/Comment; SARA is the Superfund Amendments and
Reauthorization Act of 1986. Response; See page 1-1 of
OUFS.
4. Question/Comment; For chromium the MCL is more strin-
gent than the AWQC. Response; The correct MCL and AWQC are
the same.
5. Question/Comment; On page 2-15 "floting" should be
floating. Response; See page 2-13 of OUFS. •
6. Question/Comment; On Table 3-3, why reference
Unidynamics?Response; See Table 3-3 of OUFS.
7. Question/Comment; Are attainable removal rates of TCE
99.9% or 99.99%? Response; 99.99%. See Table 7-1 of OUFS.
8. Question/Comment; On page 7-15 the discussion of RACT
is very cursory. Response; An operable unit feasibility
study is considered to be a 10% design, and as such the
description of control technologies is sufficient.
9. Question/Comment: In Table 7-4, it is indicated that
the expected removal efficiency from subunit B/C is 94/95%.
This should be noted and discussed earlier in the screening.
Response; See page 7-12 and Table 7-4 of OUFS.
10. Question/Comment: Table 7-4 focuses on 10 E-6 cancer
risk as removal criterion. Table 7-5 focuses on either 5
ppb or background. Does this distort the comparison?
Response; The different removal requirements for meeting
the various levels of cleanup has no effect on the compari-
son of technologies. If the required removal of contami-
nants to meet ARARs were also entered on Table 7-4, Air
Stripping, the values would be the same as they are on
Table 7-5, Activated Carbon. See Tables 7-4 and 7-5 of
OUFS.
RD/R9/018 B-15
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11. Question/Comment! On page 9-1, note that in situ
treatment was also screened out. Response; See page 9-1 of
OUFS.
12. Question/Comment: Why do you need to design and con-
struct wells for surface discharge? Response; To extract
contaminated groundwater and to monitor groundwater quality.
FROM EPA, TOXICOLOGY
1. Question/Comment; Consistent with my oral comments to
you and the contractor during the second week of June of the
"Draft Preliminary Public Health Endangerment Assessment"
for this site, quantitative expressions of risk should be
presented in a way to indicate that they are upper-bound
estimates developed using many, mostly conservative, assump-
tions about both the potential toxicity and exposures to
man. Therefore, phrases such as "risks up to" or "risks may
be as much as" should precede quantitative risk numbers
presented in Table 3-3 (pp 3-19). Response; See Table 3-3
of OUFS.
2. Question/Comment; Furthermore, the "uncertainties..."
section on pp. 3-21 should be expanded to include additional
areas of uncertainty inherent in the quantitative risk esti-
mates, e.g.:
a. Toxicity
(1) Choice of bioassay
(2) Choice of data, e.g., tumor site, tumor type
(3) Dose conversion, i.e., relationship between
applied dose of the parent chemical to target
organ dose of the active chemical (possibly
different than the parent chemical).
(4) Extrapolation from animal to man
b. Exposure. Type of data; uncertainty increases as
data available becomes more remote from the likely
receptor (e.g., biological measurements in blood,
tissues, etc. personal monitors concentrations in
media plus modeling uptake emission data plus model-
ing fate, transport, and update...)
Response: See page 3-21 of OUFS.
3. Question/Comment: The treatment level options under
active consideration include (a) no action, (b) removal to
meet ARARs, and (c) treatment to background levels. In
option (b), the AWQCs are considered to be among the ARARs.
For nearly all the organic contaminants at the site the
RD/R9/018
B-16
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AWQCs are the most conservative and drive the proposed
treatment level (Table 1-1 and Table 7-1). The AWQCs may
not be appropriate target treatment levels for two reasons.
First, for carcinogens, the AWQCs are concentrations in
drinking water which present an estimated cancer risk of
less than 10 E-6. From a public health perspective this
level of protection may be unduly restrictive given the fact
that subsequent treatment (chlorination) of water for
drinking may produce halomethanes at concentrations in
excess of those predicted to present cancer risks of 10 E-6.
Second, headquarters has recently provided additional
guidance on compliance with ARAR requirements (July 9, 1987
memo from J. Winston Porter to Regional Administrators and
Division Directors) which states that MCLs should be used
when available and that "The Agency is still formulating a
position with respect to the use of FWQC (AWQC) for
protection of human health." Response: The water will be
treated to attain MCL's. See Table ES-1 of OUFS.
4. Question/Comment; Will the public have a major role in
selecting, from among the treatment options considered
implementable, sufficiently effective, and technically
feasible (those presented in Chapter 9), the specific
treatment to be enforced at this site? Response; The
public and appropriate agencies will have a major role in
selecting the options as evidenced by the treatment of
groundwater in aquifers of Subunit B/C.
RD/R9/018
RD/R9/018 B-17
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