PB95-963104
EPA/ESD/R09-93/124
January 1995
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Phoenix-Goodyear Airport
(Second ESD), AZ
5/5/1993
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~
Phoenix-Goodyear Airport Area Superfund site
EXPLANATION OF SIGNIFICANT DIFFERENCES #2
for the FINAL REMEDY RECORD OF DECISION
May
1993
I.
INTRODUCTION
On September 26, 1989, the united States Environmental
Protection Agency (EPA) signed a Record of Decision (ROD) for the
final remedy at the Phoenix-Goodyear Airport (PGA) site in
Goodyear, Arizona.
The State of Arizona concurred with the remedy
selected
in the
1989 ROD.
In January
1991,
EPA
issued an
Explanation of Significant Difference (the 1991 ESD) which modified
and clarified the 1989 ROD on five points.
EPA now is modifying
the ROD a secon4 time to explain the differences between the final
remedy originally selected in the 1989 ROD and the final remedy
which will be implemented at the site.
These changes are not
fundamental alterations of the remedy described in the 1989 ROD.
Under section 117 of the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA), as amended by the
Superfund Amendment and Reauthorization Act of 1986, and .pursuant
to 40 C.F.R. section 300.435(c) (2) (ii)
(55 Fed.Reg.
8666, 8852
(March
8,
1990»,
EPA
is
required
to
publish
an
ESD
when
significant (but not fundamental) changes are being considered to
a final remedial action plan as described in a ROD.
If the changes
fundamentally alter the nature of the selected remedy, an amendment
to the ROD would be required [40 C.F.R. Section 300.435(c) (2) (ii»).
In this instance, EPA has selected a number of important changes
that modify the ROD requirements, but do not alter the hazardous
. . .". .." . .
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,
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.i
waste management approach that EPA selected in the ROD.
The
purpose for each of these changes is described in detail in Section
III of this document.
This document provides a brief background of the site, a
summary of the remedy selected in ~e 1989 ROD and how that remedy
was modified by the 1991 ESD, a description of how this ESD affects
the remedy originally selected by EPA in the 1989 ROD,
explanation of why EPA is making these changes to the ROb.
and an
EPA is
issuing this second ESD to the 1989 ROD in order to take int.o
account information received by EPA after EPA issuance of the 1991
ESD.
This ESD changes the remedy selected in the ROD for both the
northern and southern portions of the PGA site.
The northern
portion
of
the
site
consists
of
the
Unidynamics-Phoenix
Incorporated (Unidynamics) property and groundwater contamination
~.
emanating from the Unidynamics property.
The southern portion of
the site consists of the Loral Defense Systems-Arizona (Loral)
property
and
the
Phoenix-Goodyear
Airport
property. and
any
groundwater contamination emanating from these areas.
This ESD modifies the remedy selected for the northern portion
of the site as follows:
(1) change the emission control technology for the Soil Vapor
Extraction System from vapor-phase granular activated carbon (GAC)
to treatment by thermal oxidation with wet. scrubbing;
(2) change the designated end use for water treated by the
Subunit C groundwater remedy from incorporation into the community
2
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. .
potable water supply to reinjection back into the Subunit C section
of the aquifer with an option for municipal use after 19941;
(3)
suspend the remedial design and construction of the
liquid-phase GAC treatment requirement (or other similar effective
technology) from the Subunit A gro~ndwater remedy until treatment
plant influent data quality indicates the presence
of a less
volatile compound (e.g. ketones) at a concentration of 50% or more
of its site groundwater cleanup standard;
This ESD modifies the remedy selected for the southern portion
of the site as follows:
(4) change the requirement for a centralized air stripping
system for the Subunit B/C groundwater remedy to a decentralized
system (e.g. two or more independent liquid-phase GAC treatment
systems)f
(5) change the designated end use for water treated by the
Subunit B/C groundwater remedy from municipal use to reinjection
back into the Subunit B/c section of the aquifer with an option to
reconsider municipal use after 19942;
This ESD modifies the selected remedy for both portions of the"
site as follows:
(6) add the requirement that should any private or municipal
drinking water well in the vicinity of the PGA site, including but
not limited to City of Goodyear wells number 1,2,3,7,10,11 and the
1 An explanation of when municipal end-use may still be considered is explained in
Section ill.E.
2 same as footnote 1.
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Parkshadows
drinking
water
well,
have
an
occurrence
of
a
contaminant listed in Table 2-5 of the ROD in a concentration in
excess of its groundwater clean-up standard and such contamination
is related to contamination in the Unidynamics or airport areas,
such drinking water welles) shall be treated as soon as possible by
wellhead liquid-phase GAC treatment or other similar technology as
approved by EPA.
(7) establish four additional groundwater clean-up standards
for Table 2-5 of the ROD as follows:
Benzene - 5 parts per billion (ppb)
Ethylbenzene - 700 ppb
1,1,2,2 Tetrachloroethane - 0.18 ppb
Tetrachloroethene - 5 ppb
This ESD and. supporting documentation will become part of the
PGA Administrative Record.
Copies of the Administrative Record for
the PGA site including this ESD have been placed at the following
locations:
Avondale Public Library
328 West Western Avenue
Avondale, Arizona 85323
(602) 932-9415
EPA Region 9 Superfund Records Center
75 Hawthorne Street - 9th floor
San Francisco, California 94105
(415) 744-2165
EPA provided a fifteen (15) working day comment period for the
State
of
Arizona
in
accordance
with
40
C.F.R.
section
300.515(h) (3).
state
of
Arizona
comments
on
this
ESD
are
summarized in section IV of this document and are also included in
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the PGA Administrative Record file~
Pursuant to 40 C.F.R. Section
300.435(c) (2)(i), a formal public comment period was not required
for an ESD.
However EPA, at its discretion, established a public
comment period of thirty (30) calendar days to obtain written or
oral comments on the proposed ESD:
This 30 calendar day comment
period expired .on April 1, 1993.
EPA held a public meeting in the
City of Avondale on March 10, 1993.
A copy of the transcript from
the public meeting and copies of all written comments received by
EPA have been placed in the administrative record.
EPA carefully
considered all public
comments on the proposed ESD prior to
issuance of this final ESD.
Community relations activities to
support this ESD have been in accordance with 40 C.F.R. Section
300.435(c) (2) (ii) and are further described in section VI of this
document.
II.
BACKGROUND
The following provides a brief background of the PGA site,
short summaries of the remedy selected in'the original 1989 ROD and
changes to the 1989 ROD established by the 1991 ESD.
Additional
background information can be found in the 1989 ROD, the 1991 ESD
and in the PGA Administrative Record.
A.
site Backqround and Description
The PGA
site
is
located primarily
in Goodyear,
Arizona,
approximately seventeen (17) miles west o~ Phoenix in the western
part of the Salt River Valley.
A groundwater flow divide splits
the site along Yuma Road into northern and southern portions.
The
northern portion of the site consists of the Unidynamics property,
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located at 102 S. Litchfield Road and all areas with groundwater
contamination in excess of site clean-up standards related to and
emanating from the Unidynamics property.
The southern portion of
the site consists of the Loral Defense Systems property located at
1300 S. Litchfield Road, the PG1\ property, and all areas with
groundwater contamination in excess of site clean-up standards
related to and emanating from the Loral and/or PGA properties.
Attachment #1 provides a map indicating the approximate
boundaries of the Phoenix-Goodyear Airport 'Superfund site.
site
The
current
land
uses
on
and
near
the
site
are
agricultural,
industrial, and residential.
In 1981, the Arizona Department of Health Services (ADHS)
discovered that groundwater in. certain areas of the
site was
oontaminated with solvents and chromium.
EPA and ADHS conducted
additional sampling of wells in 1982 and 1983 which revealed
eighteen (18) wells contaminated with trichloroethylene (TCE).
As
a result,
EPA added the PGA site
(originally listed as the
"Litchfield
Airport
Area
Superfund
site" )
to
the
National
Priorities List (NPL) on September 8, 1983 (see Federal Reqister,
Vol. 48, No. 175, p. 40671).
other hazardous substances found at
the PGA site include acetone, methyl ethyl ketone (MEK), 1,1,1-
trichloroethane (TCA), 'l,l-dichloroethylene (DCE) ,other volatile
organic compounds (VOCs), and chromium.
Most of the groundwater and soil contamination in the southern
portion of the site is located within the Loral
and airport
properties inside an area of the site designated as Section 16.
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contaminated
"shallow qroundwater"
(hereafter
referred to
as
Subunit A groundwater) within Section 16 was addressed in the first
.phase of the remedy for the PGA Superfund site and is referred to
as the section 16 Operable unit.
A Record of Decision for the
section 16 Operable Unit was signed on september 29, 1987.
The
designated remedy of a. pump and treat system for
subunit A
groundwater has been operating since December 1989.
A primary
objective of the section 16 Operable Unit is to protect human
health
and
the
environment
by
preventing
the
migration
of
contaminated groundwater and resulting aquifer degradation.
Groundwater currently used for drink~ng water in the area of
the
site
meets
federal
and
state
drinking water
standards.
However, as municipal water supplies in the area of the site are
dependent on groundwater, future population growth in the area
could require use of groundwater in contaminated areas and may
result in potential exposure to hazardous substances.
The clean-up work in the northern portion of the site is being
carried out by Unidynamics, whereas the Goodyear Tire and Rubber
company is the lead party implementing the work in the southern
portion of the site.
EPA, with the assistarice of the Arizona
Department of Environmental Quality (ADEQ), authorizes and oversees
all clean-up activities at this Superfund site.
B.
Remedv Selected in the 1989 ROD
The ROD for the final remedy at the PGA site was signed by the
EPA Regional Administrator on September 26, 1989.
In addition to
selecting the remedial actions described below, the final remedy
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also incorporates the section 16 Operable Unit.
The groundwater
clean-up levels for the PGA site are identified in Table 2-5 of the
ROD3.
The groundwater cleanup levels for the section 16 operable
Unit are identified in Table 2-5 and in Table 1 of the 1987 ROD.
ROD Remedy for Souther. portion of PGA site
For the southern half of the site,
the remedy primarily
consists
of
extraction
and
treatment
of
contaminated
"deep
groundwater" (hereafter referred to as Subunit B/C groundwater) and
soil vapor extraction for contaminated soils.
The Subuni t B I C
groundwater remedial action requires a pump and treat system using
air stripping to remove VOCs from the groundwater.
The ROD states
that groundwater remedial action shall consist of three (3) new
Subunit B/C groundwater wells for extraction and treatment of
Subunit.B/C groundwater at a central treatment plant.
The ROD
states that the central treatment plant may be operated without
emissions controls.
In addition, the ROD requires that treated
water from the central treatment plant will be made available to
the City of Goodyear for municipal use.
The estimated total
present worth cost of the extraction and treatment facilities f?r
the groundwater remedy for the southern portion of the site is
$14,500,000.
with respect to VOC soil contamination at the southern portion
of the PGA site, the ROD selected a soil vapor extraction (SVE)
3 The groundwater cleanup levels in Table 2-5 of the ROD consist of: a) Federal and
State of Arizona legally Applicable or Relevant and Appropriate Requirements (ARARs);
and, b) other criteria used to ensure the protectiveness of the remedy (known as To -Be
Considered (TBCs».
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system with emission controls.
The SVE system will be implemented
in certain required areas within an area identified as Target Area
2 in Figure 5-2 of the ROD.
The total present worth cost of the
soil remedy for the" southern portion is estimated to be from
$3,900,000 for a phased implementation, to $5,400,000 for a single
phase implemen~ation.
'.
ROD Remedy for Northern Portion of the PGA site
The remedial action selected for the northern portion of the
site is similar to that chosen for the south and includes a
Subunit A groundwater remedy, a Subunit C groundwater remedy, and
a soil remedy.
The Subunit A groundwater remedy consists of a pump
and treat system using air stripping,
followed by liquid phase
granular activated carbon.
Vapor-phase GAC air emission controls
are required for" the Subunit A groundwater remedy.
The ROD
requires that the treated water from Subunit A groundwater remedy
be reinjected, and the treated water from the Subunit C groundwater
remedy be incorporated into the community water supply.
The
estimated present worth cost of the groundwater remedy" for the
" northern portion of the site is $14,000,000.
The soil remedy consists of a SVE system with vapor-phase GAC
air emission controls to be implemented in the target area.
ROD identifies the target" area as that area where VOCs
The
were
detected in soil samples and the area where soil gas samples
exhibited VOCs greater than 1 micrograms per liter.
The ROD
provides that this area may be expanded or reduced, as necessary,
to include removal of 99 percent of the contaminants.
In addition,
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the ROD states that excavation and treatment may be required to
remove residual contamination where soil vapor extraction is not
effective.
The estimated present worth cost of the SVE system is
$3,100,000.
c. The 1991 ESD chanaes to the 1989 ROD
The ESD .issued by EPA in January 1991 clarified and modified
portions of EPA's September 1989 ROD.
To the extent that the 1991
ESD differed from the ROD, the 1991 ESD supersedes the ROD.
1991 ESD modified the ROD as follows:
The
(1)
The 1991 ESD revised the clean-up level for methyl ethyl
ketone (MEK) in groundwater from 170 parts per billion (ppb) to 350
ppb;
(2)
The 1991 ESD set a clean-up level
for .acetone in
groundwa~er at 700 ppb;
(3)
The 1991 ESD clarified the target area for the soil
remedy in the northern portion of the site and the criteria for
establishing the clean-up levels.
On page four of the 1989 ROD,
the soil remedy target area is described as "that area where VOCs
were detected in soil samples and the area where soil gas samples
quantified VOCs greater than 1 microgram per liter.
The area may
be expanded or reduced to include removal of 99 percent of the
contaminant".
In the 1991 ESD, EPA defined these statements to
identify the soil remedy target area for the northern portion of
the PGA site to consist of target areas Band C defined by all four
circles in Figure 5-7 of the 1989 ROD;
(4)
The 1991 ESD clarified the role of soil excavation as a
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remedy
option,
should
the
selected
soil
remedy
(soil
vapor
extraction) at the northern portion of the site prove ineffective.
The 1989 ROD states on page four that "excavation and treatment may
be required to remove residual contamination where soil vapor
extraction is not effective."
In the 1991 ESD, EPA interpreted
this to mean that excavation and treatment of soil is one, but not
,
\
the only, remedial alternative EPA will consider for the soil in
the northern portion of the site if soil vapor extraction is
ineffective;
(5)
The 1991 ESD revised the selected remedy for an off-site
agricultural well referred to as the "Phillips Well" from wellhead
treatment to routine water quality monitoring.
The 1991 ESD did
not alter EPA authority to reimpose the requirement for wellhead
treatment at the Phillips Well should future monitoring indicate
that the concentration of any VOC has exceeded the clean-up level
identified in Table 2-5 of the 1989 ROD.
EPA's decision to
reimpose wellhead treatment will be based on the Agency's review of
water quality sampling results for the Phillips well.
III.
DESCRIPTION OF ESD
This ESD modifies portions of EPA's September 1989 ROD.
This
ESD does not affect the 1991 ESD.
To the extent that this ESD
differs from the ROD, this ESD shall supersede the ROD upon EPA
signature of this ESD.
The modifications to the ROD contained in
this ESD are described below.
Attachment #2 provides a condensed
overview of this ESD.
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ModificatioDS to the ROD Remedy for PGA Site-Horth
A. VaDor Treatment for the Soil VaDor Extraction System at the
Northern Portion of the site
The ROD states that the contaminated soils at the PGA site-
north (i.e. the Unidynamics area) Mill be treated by soil vapor
extraction with vapor-phase GAC emission controls.
This decision
was based on known soil contamination data as of mid-1989.
During 1991 and 1992, Unidynamics proceeded with design work
for the soil remedy a~ described in the ROD.
All of Unidynamics'
design work plans and field activities were subject to EPA approval
and oversight.
In late 1991,
Unidynamics installed two SVE
extraction wells within the soil target area designated by the ROD.
These
SVE extraction wells were
then tested for contaminant
concentr~tion and pressure data in order to establish the final
specifications
needed to build the SVE remedy.
During this
testing,
three
(3)
soil gas samples were collected from the
extracted vapor-stream, and analyzed by EPA-approved test methods.
The results are summarized below in Table 1.
TABLE J
PRELIMINARY CHARACTERIZATION OF SOIL VAPOR
-.
Concentrations (ppm volume)
Compound . Sample- - : Sample Sample Average
SVE A.l SVE A.2 SVE A-3
. 286 319 292 299.
Acetone
MEte -1327 1590 1515 1477
TCE 436 S49 - 440 475
Totals 2049 2458 2247 2251
ppm = parts per million
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. .
The
data
shown
above were
utilized
to make preliminary
calculations to estimate GAC usage rates and were also supplied to
equipment vendors as additional data for their use in evaluating
equipment requirements.
The preliminary estimates of the vapor-
phase GAC usage rates indicated e~remely high rates, in excess o~
4,000 lbs. of .GAC per day, which is much higher than the usage
.,
,
\
rates estimated at the time of the ROD.
A 4,000 lbs. per day GAC
usage rate would not only cau,se a significant increase in the
overall cost of this soil remedy but also create safety concerns
associated
with
the
transport
of
large
volumes
of
spent,
contaminated GAC canisters and the possible release of contaminated
GAC in an accident.
In addition, scientists have documented that
using vapor-phase GAC for treatment of ketones (including methyl
ethyl ketone and acetone) may cause safety concerns in regard to
potential spontaneous combustion of GAC canisters4.
As a result
of the above information, EPA directed Unidynamics to re-evaluate
GAC
in
addition
to
other
alternatives
for
the
vapor
phase
.
treatment.
In the document Evaluation of Alternatives for Treatment of
Extracted Soil Vapor durina SVE Pilot Testina, dated January 29,
1992 and revised March 13,
1992,
Unidynamics evaluated several
emissions control technologies for use during an SVE pilot Testing
4 For additional information on this subject, see the administrative record for this ESD,
document numbers 1, 2, and 3. The index of documents for the administrative record for
this ESD is provided in Attachment #4.
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programS. As a result of this evaluation, Unidynamics
"recommended: a) continued use of SVE for contaminant vapor
extraction; and, b) pilot testing thermal oxidation of the
extracted contaminant vapors with wet scrubbing of the combustion
by-products.
In thermal oxidation,- the soil vapor is heated, using
natural
gas
or
propane,
to
burn
and
destroy
the
vapor
contaminants6. "
Non-catalyzed systems typically operate between
14000F to 16000F and destruction efficiency can be in excess of
99%.
A wet scrubber unit is connected to the thermal oxidation
unit to remove hydrochloric acid in the exhaust gas.
The wet
scrubber operates by spraying water into the exhaust gas, causing
the hydrochloric acid to move from the gaseous phase to the liquid
phase.
Water from the wet scrubber unit can be discharged to a
sanitary sewer as long as the acidity of discharged liquid stream
is properly controlled.
"Thermal oxidation with wet scrubbing was approved by EPA for
SVE pilot testing for the following reasons:
- Thermal oxidation is a demonstrated technology for the
treatment of soil vapors contaminated by VOCs, and when equipped
with a wet scrubber it is accepted by the Maricopa County Bureau of
Air Pollution Control as Best Available Control Technology (BACT).
with proper operation, destruction efficiencies of greater than 99%
5 To review a~opy of this document, see the administrative record for this ESD,
document number 12.
6 For more information on thermal oxidation, see administrative record document
number 4.
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can be achieved for the types of contaminants found in the soil
target area at the unidynamics facility.
- The disposal or regeneration of large volumes of hazardous
waste (i.e. GAC canisters) is eliminated, thereby reducing the
potential hazards associated with handling and transport.
In accorda~ce with the document entitled Proposed SVE pilot
".
,
Testina
Proaram " Description,
dated October "1992
and revised
November 10, 1992, Unidynamics implemented a successful SVE/Thermal
oxidation pilot study during December 19927.
The contaminant
concentrations detected in exhaust gas exiting the SVE/Thermal
oxidation equipment during the first phase of this pilot study are
provided below in Table 2.
TABLE 2-
SVE-l EXHAUST SAMPLE ANALYSIS RESULTS
.1Bi 1~~,!tJ~II!!~~:t~~i!!i
AcctoDC 0S7 o.sa Ut ND 7SO 7SO
1,1-Dic:h10f0Cthylcec ND ND U2 ND 1 S
Methyl Edlyl XetoDC (NEX) 132 0.'7% an G.3& 300 200
-,;:-.
TetrldlJarDcthylCIIC ND HE) ND o.m 2S -
TrichJOfOCthylCIIC ('I"C2) 107 G.I1 CI.I6 GAS SO SO
N01'BS:
r."D - AzWyte 1iI'U Dot dctected at COIIcCctratiozls pouter dI&D or cqll&! to the quactitatioll ~
I Oc:c\Ip8tiocaI Safety &Dd Hc.all.h Administntioc (OSHA) 29 a:1l 1 910.1000 permisg"ble c.xpocllft limit, 8-holll time~i&flted 8YU&p.
, Americac CoI1!tftDC'C of GcMmmectaJ IDdustriaJ H)'Iier.ists (ACCiIH) lIIrcahold limit wluc. 8-bo\&r time~ipted 8YU8po
ppm = parts per million
. .' - -.....
7 Administrative Record Document No. 26.
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Under conditions 2 and 3 (Cond.2 and Cond.3) the SVE/Thermal
Oxidation system was operated at flowrates of approximately 8 cubic
feet per minute (cfm) and 15 cfm respectively.
and 4, the SVE extraction wells were closed8.
Under conditions 1
Average destruction
efficiencies (calculated from Conditions 1 and 2 inlet and exhaust
contaminant concentration data) achieved during this first phase of
the pilot study are as follows:
Compound
Averaqe Destruction Efficiencv
Acetone
Methyl Ethyl Ketone
Trichloroethylene
99.8%
98.4%
99.3%
In the report entitled SVE pilot Testinq Final Report, dated
February 1993, Unidynamics recommended use of the thermal oxidation
technolo9Y with wet scrubber unit for the vapor treatment portion
of a full-scale soil vapor extraction system9.
Based on the
success of the pilot study,
EPA approves of this Unidynamics
recommendation.
Therefore, this ESD changes the ROD requirement
for remediation of the PGA site-north soil target area from SVE
with
vapor-phase
GAC
emission
controls
to
SVE
with
thermal
oxidation and wet scrubbing on the exhaust emissions.
The ROD and
8 The analysis of certain exhaust samples taken during conditions 1 and 4, when the
SVE-l extraction well was closed and no soil vapor was being extracted are likely to be
anomalies since no contaminant detections were anticipated under those conditions.
Although the levels detected under conditions 1 and 4 were very low and present no
significant threat to human health and the environment, these anomalies will be re-tested
again when the SVE/Thermal Oxidation system is re-started.
9 Administrative Record Document No. 29
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1991 ESD requirements specifying soil target areas and soil clean-
up standards remain unchanged.
B. Subunit A Groundwater Treatment Remedv
The ROD states that the subunit A Groundwater Treatment Remedy
for the PGA site-north consists o~ pump and treat technology using
both air stripping and liquid-phase GAC with vapor-phase GAC
treatment of the air emissions.
This remedy is scheduled to be
implemented in three phases.
Phase 1 facilities will be located
solely
on
Unidynamics
property
and
consist
of
extraction,
treatment, and reinjection of Subunit A groundwater contamination
plus some limited contribution from Subunit B.
Phases 2 and 3
facilities
will
pump
and
treat
only
Subunit
A . groundwater
contamination and will be located generally within the approximate
site boundaries north of the Unidynamics property (see Attachment
#1).
The liquid-phase GAC component of the treatment remedy was
intended to remediate any groundwater contamination consisting of
ketones, primarily methyl ethyl ketone (MEK), that was not removed
during the air stripping process.
Although GAC is not a suitable
technology to remove ketones from a contaminated air stream (See
section III.A), GAC can be effective in removing ketones from a
liquid stream..
At the issuance of the ROD, EPA determined that the liquid-
phase GAC groundwater treatment unit was needed based on two
groundwater samples from two different wells at the Unidynamics
facility which indicated MEK concentrations of 11,000 ppb and 900
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ppb.
ppb.
The MEK clean-up level established by the 1991 ESD is 350
During 1991 and 1992, EPA directed UnidYnamics to implement
a special groundwater sampling program to confirm the extent and
approximate amount of HER groundwater contamination.
In accordance
with the document entitled SDecial SamDlina Event10 dated February
10, 1992, UnidYnamics implemented a focused groundwater testing of
the two wells -that indicated prior HER contamination plus a third
well
which
was
hydraulically
downgradient.
As
EPA
field
representatives during this event,
the Arizona
Department of
Environmental Quality (ADEQ) took split samples of the Unidynamics'
groundwater samples.
The data results of the Special SamDlina
Event are documented in a Unidynamics' letter report dated March 3,
1992 and an ADEQ letter reportll.
Data resul ts from both the
Unidyna~ics
and
ADEQ
samples
indicated
non-detectable
concentrations of both MEK and acetone.
In April 1992, EPA approved Unidynamics' plan to continue
searching for - ketone groundwater contamination in the targeted
three wells
as
part
of Unidynamics .
on-going quarterly well
monitoring
program.
No
significant
ketone
groundwater
contamination has been detected to date.
Therefore, in the absence
of ketone groundwater contamination, this ESD suspends immediate
implementation. of the' liquid-phase GAC unit and requires air
stripping alone as the sole Subunit A groundwater remedy treatment
10 Administrative Record Document No.8
11 See Administrative Record Document No. 10 for Unidynamics letter and
Administrative Record Document No.9 for ADEQ letter.
18
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technology.
Upon construction of the Subunit A groundwater remedy,
EPA intends to take extra efforts to monitor and analyze actual air
stripping efficiency, especially during the start-up period, to
ensure proper operation of this system.
Furthermore, should a semi-vo~atile compound, such as methyl
ethyl ketone o~ acetone, be drawn into the Subunit A groundwater
...
\
remedy
in
concentrations at or
in excess
of
50%
of
a
site
groundwater
clean-up
standard,
design
of
a
liquid-phase
GAC
treatment unit or other similar technology as approved by EPA shall
be initiated.
The treatment technology shall commence operation
immediately if the treatment plant influent reaches or exceeds the
cleanup standards selected in Table 2-5 of the ROD, as amended.
The purpose of .initiating such work at a 50% action level is to
allow augmentation of the treatment system in a timely fashion in
order to maintain continuous compliance with site treatment and
rejection requirements without any unnecessary treatment system
shut
downs.
Monitoring
efforts
. for
ketone
groundwater
contamination in the targeted- three wells and the influent and
effluent streams to and from the Subunit A Groundwater Remedy shall
be continued as EPA determines is necessary.
Continued monitoring
for ketones will facilitate prompt action if such monitoring data
indicate
that
a
50%
action
level
in
groundwater
has
been
encountered.
C. Treated Subunit C Groundwater End~use Reauirements
The ROD specifies that treated Subunit C groundwater generated
by the Subunit C Groundwater Remedy at the northern portion of the
19
-------
PGA site shall be incorporated into the community potable water
supply.
This ESD changes the required end use for treated Subunit
C groundwater from incorporation into the community potable water
supply to reinjection via groundwater injection wells or other
similar method, back into the S~unit C section of the aquifer.
EPA is making this change to the end use for the treated Subunit C
groundwater because it is likely that the costs to the City of
Goodyear may be prohibitive based on information provided to EPA by
the City for the southern portion of the site (See section III. E).
Reinjection of the treated water back into the Subunit C portion of
the aquifer at or near the Unidynamics property still makes this
water available to the City of Goodyear for municipal use via
extraction
by
a
ci ty of
Goodyear municipal
well.
EPA has
determined that reinjection of. the treated water at or below the
standards established by Table 2-5 of the ROD (as modified by the
199J: ESD and this ESD)
is protective of human health and the
environment.
If conditions allow a municipal end-use to become a
cost-effective.alternative for a Subunit C groundwater remedy at
PGA-north,
either
the
reinject"ion
or
a
municipal
end-use
alternative may be submitted for EPA review and approval
Section III.E for additional explanation).
(see
Modifications to the ROD Remedy for PGA site-south
D. Treatment Technoloav for the Subunit B/C Groundwater Remedv.
with respect to the Subunit B/C groundwater remedy for the
southern portion of the site, the ROD states that in addition to
other
requirements,
a central
treatment plant using the air
20
-------
stripping technology (without air emission controls) shall be used
to treat water from three new extraction wells.
This ESD changes
the treatment technology for the Subunit B/C groundwater remedy
from a centralized air stripping system to two or more independent
liquid-phase GAC treatment systems.
EPA is making this change to
the ROD due t~ a reduction in the estimated extraction flow rate
"
.,
\
for
the
Subunit
B/C
groundwater
remedy
and
pipeline
access
difficulties encountered when trying to des,iqn a centralized system'
on Loral and airport properties.
Based on data available at the time of issuance of the ROD,
EPA determined that Subunit B/C groundw~ter contamination emanating
from the airport property was substantial and had migrated all the
way to the Phillips wells located a~out two (2) miles west of the
airport property.
Subsequent to the ROD, EPA directed the Goodyear
Tire and Rubber Company to design and implement a detailed Subunit
B/C
groundwater
contamination
investigation
and
delineation
program.
The work consisted of: (a) investigating and addressing
eight
old
production wells
on
Loral
and
airport
properties
suspected to be conduits of contamination from Subunit A to Subunit
B/C groundwater;
and,
(b)
strategically installing
seven new
Subunit B/C groundwater monitoring wells on the Laral and airport
properties.
The results of this investigation are detailed in the report
entitled Conceptual (30%) Design Report for the Ground-Water Remedv
at
the
Phoenix-Goodyear
Airport
Superfund
site
in
Goodvear.
21
-------
Arizona. dated November 16, 199212.
This report concludes that
the Subunit B/C contamination at the Loral/airport facility is much
less than the amount identified in the ROD.
This reduction in the
volume of Subunit B/C contamination has caused the estimated
extraction flow rate to decrease from 2200 gallons per minute (qpm)
to about 700 qpm.
The siqnificantly reduced extraction rate
allowed liquid-phase GAC to become a viable treatment alternative.
In addition, early in the desiqn process several access problems
were identified when attempting to design the extraction and
injection well pipeline network for a centralized treatment system.
These
logistical
and
access
difficulties
included
locating
pipelines around numerous roads, buildings, and railroad tracks as
well as Federal Aviation Administration (FAA) requirements which
restrict-the location and height of an air stripping tower.
Use of
independent liquid-phase GAC systems reduces the overall length of'
pipelines necessary for the treatment system and reduces the impact
of FAA requirements.
While
retaining
the
pump
and
treat
concept
for
the
remediation of contaminated Subunit B/C groundwater at the southern
portion of the PGA site, this ESD changes the treatment technology
from a centralized air stripping system (without air emission
controls) to two or more independent liquid-phase GAC treatment
.......
systems.
Although the air stripping remedy described in the ROD
was determined EPA to be protective of human health and the
12 Administrative Record Document No. 27
22
-------
environment, the liquid-phase GAC systems required by this ESD have
an added. level of protectiveness since they further reduce the
discharge of contaminants into the air.
E. Treated Subunit B/C Groundwater End-use Reauirements
The ROD requires that treated~water generated by the Subunit
B/C Groundwater Remedy for the southern part of the PGA site be
'.
\
provided to the City of Goodyear for municipal use.
This ESD
changes
the ultimate disposition of the treated
Subunit B/C
groundwater from City of Goodyear municipal use to reinjection (via
groundwater injection wells) back into the Subunit B/C section of
the aquifer underneath the Loral and/or airport properties.
As
explained
further below,
if
after
1994
EPA
determines
that
operation and maintenance of Subunit B/C groundwater reinjection
wells are not the most cost-effective end-use alternative, plans
and specifications for conversion to a municipal end-use may be
prepared and submitted for EPA review and approval at that time.
As stated. in paragraph D. above, at the writing of the ROD in
1989 EPA estimated that up to 2200 gpm of Subunit B/C groundwater
would have to be extracted and treated.
Reinjection of the treated
water was screened out at that time due to concerns that such a
high
flow rate
of
treated water would have
necessitated an
abundance of costly groundwater injection wells which can be
subject to operational difficulties.
EPA designated the City of
Goodyear as the primary recipient of treated water because of its
proximity to the site.
However,
as
a
result
of
the
Subunit
B/C
investigation
23
-------
described
in paragraph D.
above,
the
extent
of
Subunit
BIC
groundwater contamination was decreased, thereby decreasing the
extraction flow rate of water to be remediated from about 2200 qpm
to about 700 qpm.
Because this water is high in naturally
occurring total dissolved solids (TDS), TDS levels must be reduced
prior to incorporation in a municipal water supply.
The city of
Goodyear estimated that reduction of TD$ to acceptable levels at a
2200 qpm flow rate would cost approximately $13,000,00013.
EPA is
proposing this change to the end use for the treated Subunit B/C
groundwater primarily based on the prohibitive cost the City of
Goodyear would encounter in accepting this water for municipal use.
In addition, the reduced flow rate results in an increased cost-
effectiveness of the reinjection alternative by reducing the number
of reinj~ction wells required.. Reinjection of the treated water
back into the Subunit B/C portion of the aquifer at or near the
Loral and/or airport properties still makes this water available to
the City of Goodyear for municipal use via extraction by a City of
Goodyear municipal well.
Based on comments on the proposed ESD received from the city
of Goodyear, EPA is allowing certain limited opportunities for a
municipal end-use alternative for treated Subunit B/C groundwater.
For Subunit B/C groundwater remedial action planned pursuant to the
document Final Desian Report for the Subunit B/C Ground-Water
Remedv at the Phoenix-Goodyear Airport Superfund Site in Goodvear.
13 Administrative Record Document No.5
24
-------
Arizona and scheduled for construction during 1993 and 1994, the
required end-use requirement for treated Subunit SIC groundwater
shall be reinjection back into the Subunit SIc portion of the
aquifer.
If
after
1994,
EPA determines
that operation and
maintenance of
Subunit SIC groundwater reinjection wells for
end-use
alternative, plans
and specifications
for a modified
\
\
Subunit SIC gr~undwater remedial actions are not a cost-effective
reinjection system or for conversion to a ~unicipal end-use may be
prepared and submitted for EPA review and approval at that time.
Conversion of end-use alternatives shall not provide an opportunity
to delay or suspend remedial action work.
For other Subunit SIC groundwater remedial actions that are
not constructed during 1993-94 pursuant to the Goodyear Tire and
Rubber C.ompany document entitled Final Desiqn ReDort
for the
Subunit SIC Ground-Water Remedv at the Phoenix-Goodyear Airport
Superfund site in Goodvear. Arizona, this ESD requires that either
of the following two end-use alternatives to be submitted for EPA
review
and approval: a) reinjection back into the Subunit B/C
portion of the aquifer; or, b). municipal use.
This requirement
applies to post-1994 Subunit SIC groundwater remedial actions at
both PGA-south and PGA-north.
EPA has determined that either alternative, municipal use or
reinjection of the treated water, is protective of human health and
the environment if such water is treat to a quality at or below the
standards established by Table 2-5 of the ROD (as modified by the
1991 ESD and this ESD).
It must be noted here that any end use
25
-------
alternative must be consistent with state laws and may be subject
state permitting requirements.
The state of Arizona has determined
that the reinjection alternative required by this ESD is consistent
with state law and not subject to a state permit.
However, any
attempts to desiqn and implement p municipal end use alternative
shall be subject to state and local law including permitting
requirements, 'if any.
site-wide Modifications
F. Drinkina Water Well Protection.
This ESD adds the following
requirement to the ROD: In the event that any private or municipal
drinking water well,
including,
but not
limited to,
ci ty of
Goodyear wells number 1,2,3,7, 10, 11, and Parkshadows drinking water
well, has an occurrence of a contaminant listed in Table 2-5 of the
ROD (as revised by the 1991 ESD and this ESD) at a concentration
equal to or in excess of its groundwater clean-up standard, and
such' contamination is related to ,releases of contamination at the
PGA site north or south, such private or municipal drinking water
welles) shall be treated by wellhead liquid-phase GAC treatment (or
other similar technology approved by EPA) as soon as possible.
It
must be noted here that in order to implement wellhead treatment in
a timely fashion,
appropriate actions
(i.e.
remedial design,
procurement, and construction activities) should be taken before
water quality in a drinking water well attains a contaminant
concentration at its groundwater cleanup standard.
The immediacy
of such proper design, procurement, and construction activities
shall be based on EPA assessment of trends in drinking water well
26
-------
water quality.
Water quality information obtained by or for EPA since 1982
for City of Goodyear municipal wells and the private Parkshadows
drinking water wells are provided in the Administrative Record for
this ESD14.
These data indicate~that, with some exceptions to
date, no City ~f Goodyear or Parkshadows drinking water wells has
had or currently has contamination in excess of the groundwater
.....
\
\
clean-up standards specified for this site during the times and.
dates such wells were sampledlS.
These exceptions were each minor
in nature.
Moreover, EPA does not anticipate that groundwater
contamination will in the future be detected at significant levels
in the Parkshadows or City of Goodyear municipal drinking water
wells at or near the PGA site.
However, in order to establish a
14 Administrative Record Document No. 31
15 For the last five years, TCE concentrations in City of Goodyear drinking water wells
and the Parkshadows drinking water wen have remained at levels less than 1 ppb. Two
documented occurrences of TCE concentrations found to be in excess of the 5 ppb TCE site
cleanup level are: 1) Well COG#2 had a single occurrence (sample date 4/14/87)
indicating 8.0 ppb TCE; and 2) Wen COG#1 had a single occurrence (sample date
5/17/84) indicating 6.8 ppb TCE. Other single exceedences of the TCE cleanup level in
well COG#3 (sample date 10/09/87) and the Parkshadows drinking water well (sample date
7/19/88) appear to be erroneous since these particular sample results are not consistent
with historical sampling data for these wells which have consistently shown TCE levels at
less than 1 ppb TCE. City of Goodyear wells numbers 4 and 5 have had documented TCE
concentrations above the TCE clean-up standard (see Administrative Record Document No.
31). However, well number 4 had been used primarily for fire protection and not for
drinking water. Well number 4 was appropriately abandoned by filling the well with cement
to the land surface. TCE concentrations above 5 ppb were first detected in well COG#5 in
July 1985, but this well had been permanently disconnected from the City's service system
in September 1983. Therefore, COG#5 was not being used for drinking water purposes at
times when TCE concentrations above 5 ppb was present in water generated by this well.
27
-------
clear directive for protection of public health in the case of this
unlikely event,
EPA has decided to add the wellhead treatment
requirement as
descr ibed above.
It must be noted that this
drinking water wellhead treatment requirement may not be determined
by EPA to be an adequate long-term .response action for qroundwater
contamination of a drinking water well.
The purpose of this well-
head treatment" requirement is to protect public heath in a timely
fashion by ensuring the quality of drinking water being extracted
from drinking water wells in or near the PGA"site.
G.
Groundwater Clean-uD Levels for Benzene. Ethvlbenzene. 1.1.2.2
Tetrachloroethane. and Tetrachloroethene.
Table 2-5 of the ROD
provides the groundwater clean-up standards for the PGA site.
The
1991 ESD revised the MEK groundwater clean-up standard to be 350
ppb and ~dopted 700 ppb as the groundwater clean-up standard for
acetone.
During the 1992 soil gas testing in the soil target area
at the Unidynamics facility, four contaminants were detected that
were not detected at the writing of the ROD or the 1991 ESD.
These
four
new
contaminants
are
benzene,
ethylbenzene,
1,1,2,2-
tetrachloroethane,
and
tetrachloroethene
(also
known
as
perchloroethene or PCE).
Because migration of these contaminants
to groundwater is possible, EPA has added clean-up levels for these
contaminants to Table 2-5 of the ROD.
In addition, groundwater
clean-up levels for these four contaminants are needed to determine
their corresponding clean-up levels in the soil upon applying the
EPA-approved contaminant transport model.
As with all other Table
2-5 contaminants,
the soil clean-up levels for these four new
28
-------
. .
contaminants
shall
be
determined
based
upon
a
decision-tree
described in the ROD and are related to their clean-up levels in
qroundwater.
It must be noted here that consistent with the "petroleum
exclusion" allowed by CERCLA, the groundwater cleanup standards for
.
benzene and ethylbenzene are not applicable to actions related to
"'
,
the clean up of petroleum products released from a petroleum
underqround storage tank.
EPA has added clean-up levels for these four new contaminants
to Table 2-5 of the ROD as follows:
Benzene: 5 micrograms per liter or 5 ppb16
Ethylbenzene: 700 micrograms per liter or 700 ppb17
Tetrachloroethene: 5 micrograms per liter or 5ppb18
1,1, 2, 2-tetrachloroethane: 0.18 micrograms per liter
or 0.18 ppb19
The
above
groundwater
clean-up
standards
for
benzene,
tetrachloroeth~ne, and ethylbenzene are the maximum concentrations
levels
(MCLs)
for these contaminants established by the Safe
Drinking Water Act.
Therefore, the clean-up standards for benzene,
16 Reference: Region 9 Environmental Protection Agency Drinking Water Standards and
Health Advisories Table, December 1992 (see Administrative Record Document No. 30).
17 same as 13. .
18 same as 13.
19 Reference: Human Health-based Guidance Levels for the Ingesdon of Contaminants
in Drinking Water and Soil. Arizona Department of Environmental Quality, June 1992. (see
Administrative Record Document No. 16).
29
-------
tetrachloroethene and ethylbenzene are ARARs.
Since the MCL for tetrachloroethene had not been established
. in 1987, EPA set its groundwater clean-up level to be 3 ppb in
Table 1 of the 1987 ROD.
Therefore, this action hereby modifies
the tetrachloroethene groundwater ~lean-up level listed in Table 1
of the 1987 ROD to be 5 ppb in addition to adding this same level
to Table 2-5 of the 1989 ROD.
In the absence of an MCL and EPA risk reference dose data, the
groundwater clean-up standard for
1,1,2,2-tetrachloroethane is
based on the ADEQ action level for groundwater found in the ADEQ .
document Human Health-Based Guidance Levels for the Inqestion of
contaminants in Drinkinq Water and Soil, dated June 1992.
Since
ADEQ does not promulgate their action levels, the clean-up standard
for 1,1,2,2-tetrachloroethane is a "to-be-considered" (TBC) clean-
up level and not an ARAR.
Attachment #3 provides an updated version of Table 2-5 after
incorporating modifications established by the 1991 ESD and by this
ESD.
IV.
SUPPORT AGENCY COMMENTS
The Arizona Department ot" Environmental Quality (ADEQ) and the
Arizona Department of Water Resources (ADWR) reviewed, concurred
and provided comments' on the proposed ESD dated March 1993.
Comments regarding this proposed ESD submitted to EPA by these two
state of Arizona agencies are summarized below.
ADWR
concurred with
the proposed
ESD and
submitted the
following three comments:
30
. .
-------
1)
The
beneficial
use
of
treated
groundwater
(re-
injection)
is consistent with Arizona Revised statues Title 45
(Pages 21-23).
ADWR strongly encourages re-injection of treated
water at Superfund sites.
If there are any future changes in end
use, the new end uses(s) must be cQnsistent with state laws.
2) Pu~suant to A.R.S. 45-454.01, no permit is required to
,
:,
\
withdraw
groundwater
in
the
case
of
re-injection.
Because
withdrawal of groundwater will take place within a Superfund site
and because
all water will
be re-injected,
no
Poor Quali ty
Groundwater withdrawal Permit will be needed from ADWR.
Again, if
end use changes from re-injection, a permit may be required.
3) Any groundwater withdrawn by the City of Goodyear as
"recovered" re-injected water (Page 23) will be considered to be
withdrawn-pursuant to the' city's service area right and will count
against the city's gallons per capita per day (GPCD).
.ADEQ considered the proposed ESD to be an adequate document
and submitted the following four comments:
1) ADEQ still recommends that EPA include a reference in
the ESD to the phased groundwater remedy and the proposed Subunit
B groundwater remedy for PGA-north.
2) ADEQ appreciates the fact that EPA has described the
"trigger level" for ketone concentrations as 50% of the compounds'
clean-up standards.
ADEQ would, however, like the assurance that
adequate testing wili be conducted on the efficiency of the
groundwater air
stripping
system,
since
liquid-phase granular
activated carbon (GAC) may not be required.
31
-------
3) Conditions 1-4 of Table 2 on page 15 of the ESO should
be
explained
in
the text
of
the
ESO.
Also,
the
system's
destruction efficiency for
acetone,
methyl ethyl ketone,
and
trichloroethylene, as determined during the pilot testing period,
should be provided in the table.
~.
4) The ESO should state that "ppm" is an abbreviation for
"parts per mil"lion" (also applicable to Table 1).
Comments numbers one and two from ADWR have been incorporated
into this ESO.
ADWR's comment number three required no action with
respect to this ESD but is provided for informational purposes. -
All four of the above ADEQ comments have been addressed and
incorporated in this ESD.
V.
STATUTORY DETERMINATIONS
Considering the new information that has been developed and
the changes made to the selected remedy upon implementation of this
ESD," EPA believes that the remedy for the PGA site will remain
protective of human health and the environment, will continue to
comply with federal and state requirements that are applicable or
relevant and appropriate to this remedial action, and will continue
to be cost-effective.
In addition,
the revised -remedy uses
permanent solutions and alternative treatment technologies to the
maximum extent practicable for this site.
One or more of the
changes and clarifications contained in this ESD are significant,
but none of the proposed changes fundamentally change the remedy.
VI.
PUBLIC PARTICIPATION ACTIVITIES
EPA has presented these changes to the remedy in the form of
32
-------
an ESD because the changes are of a significant but not fundamental
nature.
However,
in order to promote public participation, EPA
provided the public with a thirty (30) day comment period on a
proposed ESD dated March 1993.
In accordance with section 117(c)
of CERCLA, 42 U.S.C. section 9617{C),
EPA published in the West
Valley View newspaper and the Arizona Republic newspaper a notice
that describes the proposed ESD and identified the final due date
for public comments as April 1,
1993.
In order to collect
additional public comment, EPA held a public meeting in the City of
Avondale
during the public comment period on March 10, 1993.
EPA
will again publish in the West Valley View and Arizona Republic
newspapers a notice that describes this final ESD and announces its
availability for review.
In accordance with 40 C~F.R.
Section
300.435(C)(2)(ii), this final ESD and all documents that support
the changes and clarifications herein will be contained in the
Administrative Record for the PGA site prior to the commencement of
the remedial actions affected by the final ESD.
John J:L w":"""
Acting Regional Administrator
S". S". 4~
Date
33-
-------
-ATTACHMENT 11
- .
Approximate Boundaries of
Phoenix Goodyear Airport Area Superfund Site
Camelback Road
Indian School Road
o en ::D m r- 0
::;:
o 0) CD E. n '<
- ~ II) ii" ::r (I).
- <"
o 3 - II)
Thomas Road !.. '"' i: '"'
~ fI' a. -
r > ::D > :D
I) < 0 < 0
::s CD II) CD 0)
CD ~ Q. ~ D-
C C
CD CD
McDowell Road
Van Buren Street
Yuma Road
~
CD
>
a:
Lower Bue eye Road
. " 85
t'\\Q"'lIa;r .
Broadway
GOa River
KEY
Approximate
- - - Site Boundaries
\pge\lllos\~Q ,...0217'83 I.~J
-------
ATTACBHENT #2
overview of the modifications made by Explanation of Significant
Differences (ESD#2) to the Phoenix-Goodyear Airport (PGA) Area
Superfund site September 1989 Record of Decision (ROD). See
Attachment #3 for a listing of modifications to the groundwater
clean-up standards at the PGA Superfund site.
The Oriainal 1989 ROD Si~e Clean-up
~
'The Si~e Clean-up Plan as modified
bv ESD#2
Airoort Area
- Soils: Soil vapor extraction
with vapor-phase carbon
emission controls.
Airoort Area
..
'"
\
- Soils: same as 1989 ROD.
- Deep Groundwater: Pump and
treat at a centralized air
stripping plant. Provide treated
water ~o City of Goodyear.
- Shallow Groundwater: Incorpor-
atated 1987 Record of Decision
requirement for pump and treat
at a centralized air stripping
plant with vapor-phase carbon
emission controls. Reinject
treated water.
- Deep Groundwater: Pump and treat
at decentralized liquid-phase GAC
treatment units and reinject treated
water back into deep groundwater
zone.
- Shallow Groundwater: same as 1989
ROD.
Unidvnamics Area
Unidvnamics Area
- Deep Groundwater: Pump and
treat at a centralized air
stripping/liquid-phase carbon
treatment plant with vapor-
phase carbon emission controls.
Provide treated water to City of
Goodyear.
- ~: same as the 1989 ROD except
treat extracted contaminant vapors
by thermal oxidation and wet
scrubbing.
- Deep Groundwater: same as the 1989
ROD except reinject treated water
back into deep groundwater zone.
- Soils: Soil vapor extraction
with vapor-phase carbon emission
controls.
- Shallow Groundwater: Pump and
treat at a centralized air
stripping/ liquid-phase carbon
treatment plant with vapor-.
phase carbon emi~sion
controls. Reinject treated
water.
- Shallow Groundwater: same as the
1989 ROD except suspend
implementation of the liquid-phase
carbon unit until warranted.
Additional Site-wide Reauirements
Additional Site-Wide Reauirements
- none.
- Liquid-phase carbon treatment
at the well-head for drinking water
wells contaminated by Airport or
unidynamics areas.
- Add 4 n~w groundwater standards.
-------
. ~.
..
ATTACBKEN'r #3
A summary of the legally applicable state and federal requirements
and other criteria for qroundwater clean-up levels as reported in
Table 2-5 of the September 1989 Record of Decision for Phoenix-
Goodyear Airport Area Superfund site including modifications
established by the January 1991 Explanation of Significant
Differences (1991 ESD) and modific~tions established by ESD#2.
All Concentrations are in micrograms per liter.
ComDound
1,1-Dichloroethylene
1,2-Dichloropropane
Chloroform
Toluene
Trichloroethylene
Trichlorofluoromethane
Carbon Tetrachloride
Methylene Chloride
Methyl Ethyl Ketone *
Xylenes .
Antimony
Arsenic -
Barium
Beryllium
Cadmium
Chromium
Lead
Mercury
Nickel
Selenium
Silver
Zinc
Acetone **
Benzene ***
Ethylbenzene ***
Tetrachloroethene'***
1,1,2,2-tetrachloroethane ***
CleanuD Level
7
1
100
340
5
1
5
1
350
440
1.46
50
1,000
0.0039
10
50
50
2
15.4
10
50
5,000
700
5
700
5
0.18
* Revised groundwater cleanup level established by the 1991 ESD
** New groundwater cleanup level established by the 1991 ESD
*** New groundwater cleanup levels established by ESD#2
------- |