PB97-963116
EPA/541/R-97/040
March 1998
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Tucson International Airport Area,
(Areas A & B Groundwater OU)
Tucson, AZ
2/27/1997
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TUCSON INTERNATIONAL AIRPORT AREA SUPERFUND SITE
Tucson, Arizona
FINAL EXPLANATION OF SIGNIFICANT DIFFERENCES (ESD#1)
to EPA's August 1988 Record of Decision for Groundwater Remediation
[Note: This document primarily concerns the groundwater remedy
for the Arizona Air National Guard Base also known as Area B-
west.]
February 1997
I. INTRODUCTION
In August 1988, the United States Environmental Protection
Agency (EPA) issued a Record of Decision (ROD) for groundwater
cleanup at the Tucson International Airport Area (TIAA) Superfund
Site. The State of Arizona concurred with the remedy selected in
EPA's 1988 ROD. This ROD specified the cleanup actions to be taken
for two areas of groundwater contamination (Area A and Area B) both
located north of Los Reales Road in the southside district of
Tucson, Arizona. Groundwater contamination at the TIAA site south
of Los Reales Road is addressed by a 1985 ROD issued by the U.S.
Air Force.
Areas A and B are shown on Figure 1 (attached) . Area A is
also known as the Tucson Airport Remediaton Project, or "TARP".
Area B consists of two portions: Area B-east consists of
groundwater contamination associated with the Burr-Brown
Corporation property, and Area B-west consists of groundwater
contamination associated with the 162nd Fighter Group, Arizona Air
National Guard (ANG) Base.
The purpose of this Explanation of Significant Differences
(ESD#1) is to change and clarify some aspects of the groundwater
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remedy to be implemented at Area B-west (the ANG Base) . ESD#1
explains the significant differences between the remedy for the
Area B-west originally selected in the 1988 ROD and the remedy
which is to be implemented at this time. The 1988 ROD requirements
for Area A and Area B-east are not changed or modified in any way
by this BSD. The changes to the remedy at Area B-west are not
fundamental alterations of the remedy described in the 1988 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) (i) (55 Fed.Reg. 8666, 8852
(March 8, 1990)), EPA is required to publish an BSD 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
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 groundwater remedy selected in the 1988 ROD, a
description of how this BSD affects the remedy originally selected
by EPA in the 1988 ROD, and an explanation of why EPA made these
changes to the ROD. EPA is issuing this ESD#1 to the 1988 ROD in
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order to take into account information received by EPA after
issuance of the 1988 ROD.
As stated above, this ESD#1 changes the remedy selected in the
ROD only for Area B-west, which consists of groundwater
contamination associated with the ANG base located at 1500 East
Valencia Street in Tucson, AZ.
This ESD#1 modifies the remedy selected for the Area B-west
portion of the site as follows:
(1) use Cascade Tray Air Strippers instead of Packed Column
Aeration Air Strippers; and,
(2) use well reinjection as the end use of the treated
groundwater instead of municipal drinking water usage.
In addition, it should also be noted that this ESD#1 allows for the
following clarifications to the Area B-west groundwater remedy:
(1) allow for voluntary use of Granular Activated Carbon (GAC)
to control vapor-phase volatile organic compound (VOC) emissions to
the atmosphere instead of using no air pollution control devices.
(2) clarify that the treated water standards for water
intended to be reinjected back into the regional aquifer shall be
Federal Safe Drinking Water Act Maximum Contaminant Levels (MCLs).
All other requirements of the 1988 ROD remain intact and
unchanged. Thus, the treated groundwater standard continues to be
1 in 1 million aggregate risk factor (which translated to 1.5 parts
per billion for TCE and MCLs for all other contaminants) in water
intended for municipal drinking water uses. The in-situ
groundwater cleanup standards shall continue to be MCLs for all
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contaminants contained within the Area A or Area B groundwater
plumes.
The proposed ESDttl dated December 1996, public comments
received on the proposed ESD#1, this final ESD#1, and the
supporting documentation for this BSD process has become part of
the Administrative Record for the 1988 ROD. Copies of the
Administrative Record specifically for this ESD#1 are available for
review at the following two locations:
TCE Superfund Information Library
El Pueblo Neighborhood Center, Building B-2
101 W. Irvington
Tucson, AZ 85714
(520) 889-9194
(520) 741-8818 fax
EPA Region 9 Superfund Records Center
95 Hawthorne Street - Suite 403S
San Francisco, California 94105
(415) 536-2000
If additional information becomes available, EPA will revise the
Administrative Record to reflect such material. The index to the
ESD#1 Administrative Record is attached to this document as
Attachment 1.
II. BACKGROUND
The following provides a brief background of the TIAA site,
Area B-west, and the 1988 ROD. Additional background information
can be found in the 1988 ROD and its Administrative Record.
A. Site Background and Description
The TIAA Superfund site is located on the southside of Tucson,
Arizona. Figure 1 provides a map indicating the approximate site
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boundaries of the TIAA Superfund site. The current land uses on
and near the site are commercial, industrial, and residential.
In 1981, organic chemicals -- primarily trichloroethylene or
"TCE", a solvent that was commonly used by electronic, military,
and aerospace industries -- were found in groundwater in southwest
Tucson. EPA proposed the TIAA Superfund site for inclusion on the
National Priorities List (NPL), a list of federally designated
significant hazardous waste sites, on December 30, 1982. The TIAA
site attained final NPL status on September 8, 1983. As
contaminated wells were ,identified, the City of Tucson took
measures to make sure that no water with a chemical exceeding State
or Federal standards was delivered to the public. The drinking
water standard for TCE is 5 parts per billion (ppb).
Soon thereafter, EPA and the Air Force agreed, for purposes of
investigation of groundwater contamination, to divide the site at
Los Reales Road. The Air Force issued its ROD in 1985 for
groundwater contamination south of Los Reales and commenced
operation of a groundwater extraction and treatment system for this
same area in 1987. In 1984-88, EPA, with the assistance of state
agencies, identified areas of groundwater contamination north of
Los Reales Road, and designated them Areas A and B as shown in
Figure 1. On March 3, 1988, EPA released for public review and
comment the draft "Feasibility Study for Ground Water Remediation
in the Tucson Airport Area," which proposed a preferred groundwater
cleanup remedy for Areas A and B. After extensive community
relation activities, EPA issued its August 1988 ROD.
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Drinking water for the City of Tucson continues to be tested
regularly for compliance with State and Federal standards. In
addition, EPA has taken efforts to ensure that no known private
well users on the southside of Tucson are drinking contaminated
groundwater. However, because private and municipal water supplies
in the area of the site are dependent on groundwater, EPA's stated
strategy in its 1988 ROD is to return the portions of the regional
aquifer contaminated by facilities within the TIAA Superfund site
back to drinking water quality.
In the late 1980's, the U.S. National Guard Bureau (NGB),
which is the lead federal agency at the federally owned and
operated ANG Base, took over investigations of the ANG Base from
EPA. Under a CERCLA Remedial Investigation/Feasibility Study
(RI/FS) , NGB assumed the lead role from EPA to investigate the Area
B-west groundwater contamination. In addition, the NGB initiated
a RI/FS for potential soil contamination at the ANG Base. In
October 1994, NGB, EPA, and the State of Arizona signed a Federal
Facility Agreement (FFA) outlining their respective future
responsibilities and obligations regarding the cleanup of
contamination at the ANG Base. NGB issued its final groundwater
and soils RI report in June 1995 and final soils FS report in
November 1995. EPA, with the assistance of the Arizona Department
of Environmental Quality (ADEQ) , oversaw all of the NGB's
investigation activities at1the ANG Base.
Pursuant to the FFA, the NGB is responsible for designing and
implementing the groundwater remedy for Area B-west required by
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EPA's 1988 ROD. However, due to additional information obtained by
the NGB and EPA during the NGB's RI/FS studies, EPA determined that
some changes to the 1988 ROD concerning the Area B-west remedy were
warranted.
B. Remedy Selected in the 1988 ROD
The ROD for the groundwater remedy north of Los Reales Road at
the TIAA Site was signed by the EPA Regional Administrator on
August 22, 1988. In addition to selecting the cleanup actions
described below, the 1988 ROD also establishes the cleanup levels
for contaminated groundwater that is extracted out of the regional
aquifer and treated by a groundwater remediation system. These are
known as the "treated water" standards. The 1988 ROD also
established the cleanup levels for the contaminated groundwater
which remains underground in the regional aquifer. These are known
as the "in-situ groundwater" cleanup standards. The treated water
standards and the in-situ groundwater clean-up standards identified
in the 1988 ROD are provided in Attachment 2. The standards
identified in Attachment 2 apply to groundwater remediation systems
required in the 1998 ROD for both Areas A and B. The rest of this
document will focus solely on the ANG Base, referred to as Area B-
west in the 1988 ROD.
C. 1988 ROD Remedy for Area B-west (ANG Base)
For the Area B-west portion of the TIAA site, the groundwater
remedy primarily consists of extraction and treatment of
contaminated groundwater in the upper divided regional aquifer.
The 1988 ROD goes on to state that this remedial action requires a
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pump and treat system using packed column aeration air stripping to
remove VOCs from the groundwater. Extraction from the upper
divided regional aquifer was selected to contain and prevent
migration of contamination and will remove the unacceptable
contaminant levels from areas where they are currently believed to
be. Packed column aeration air stripping was chosen/for treatment
because this method provides virtually the same public health
protection as other technologies with substantially less cost. The
198.8 ROD suggests that another treatment method for the Area B-west
remedy may be used if it is cost-effective or more easily
implementable while still offering the same level of protection of
human health and the environment and complying with all Applicable
or Relevant and Appropriate Requirements (ARARs), including those
contained in Title 45 of the Arizona Code.
With respect to air emissions, the 1988 ROD states that the
low levels of contamination in Area B-west indicate that no air
emission controls would be needed on the packed column(s).
The estimated total present worth cost of the extraction and
treatment facilities for the groundwater remedy for Area B-west was
approximately $1,00(3,000 in 1988.
III. DESCRIPTION OF ESDttl
This ESD#1 changes and clarifies the groundwater remedy EPA
intends to have implemented at Area B-west (the ANG Base) and
modifies portions of EPA's August 1988 ROD concerning Area B-west.
This ESD#1 does not affect Area A or Area B-east. To the extent
that this ESD#1 differs from the ROD, this ESD#1 shall supersede
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the ROD upon EPA signature of this ESD#1. The modifications to the
Area B-west groundwater remedy described below do not cause a
significant change to the $1,000,000 cost estimate found in the
1988 ROD. The modifications to the 1988 ROD contained in this
ESD#1 are described below. Attachment 3 provides a condensed
overview of this ESD#1.
A. Required Modifications to the Area B-west Remedy
1. Cascade Tray Air Strippers
The 1988 ROD requires a pump and treat system using packed
column aeration air stripping to remove VOCs from the groundwater
in Area B-west. In the seven years since the 1988 ROD was signed,
many technology studies on how to improve air stripping technology
have been conducted. The NGB, via its consultant ERM West Inc.,
surveyed these studies and recommended Cascade Tray Air Stripping
instead of packed column aeration air stripping. ERM West's design
analysis for the Area B-west groundwater remedy entitled
Preliminary Design Report for the Air National Guard Ground Water
Extraction and Treatment System dated March 1995 ("Preliminary
Design Report") found that Cascade Tray Air Stripping is more
suitable and cost-effective than packed column aeration for the
conditions found at Area B-west. The Cascade Tray Air Stripper is
similar to the Packed Column Aeration in that both methods equally
remove VOCs from water through the use of air stripping. For the
conditions found at Area B-west, the Cascade Tray Air Stripping is,
however, superior to Packed column Aeration method because it is
easier to maintain, fouling and breakdowns can be better avoided,
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and continuous operation is better ensured. Therefore, the 1988
ROD for Area B-west is hereby modified to allow the use of Cascade
Tray Air Stripping groundwater treatment technology.
2. Well Reinfection of Treated Groundwater
The 1988 ROD implies that treated groundwater generated by the
groundwater remedy for Area B-west would be incorporated into
Tucson's municipal drinking water supply. This ESD#1 hereby
modifies the 1988 ROD for Area B-west to require that treated
groundwater from. Area B-west be reinjected via groundwater
injection wells back into the upper divided portion of the regional
aquifer.
EPA made this change to the end use for the treated ground-
water for the following reasons:
(1) By letter dated October 19, 1994, the City of Tucson
informed the National Guard Bureau (NGB) that the City can not
and will not accept delivery of the NGB treated groundwater
directly into the Tucson drinking water distribution system;
(2) During a NGB community meeting held on October 19, 1994,
strong opposition was voiced by several community members
against delivery of treated groundwater into the drinking
water distribution system; and,
(3) Treated water reinjection was fully analyzed by EPA in the
feasibility study and proposed plan for the 1988 ROD. The
feasibility study found treated water reinjection to be
compliant with all federal and state applicable or relevant
and appropriate requirements (ARARs) including the state's
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Groundwater Management Act.
It should also be noted that, although it is not an ARAR, City of
Tucson initiative Proposition 200, which was made effective by
Tucson voters on November 13, 1995, bars the City from delivery of
treated water for drinking water purposes if such water originated
from a polluted source.
B. Clarifications to the Area B-west Remedy
1. Air Emission Controls.
The 1988 ROD states that the low levels of contamination in
Area B groundwater indicate that no air emission controls will be
needed on the groundwater treatment packed column(s) . Pitna County
Air Quality Control Regulation 17.12.090 Sub-Paragraph E, an ARAR
in the 1988 ROD, requires that Reasonably Available Control
Technology (RACT) , such as GAG, be installed on any new air
stripping facility having the potential to emit in excess of 2.4
pounds per day of airborne VOCs. The NGB document, Design for
Ground Water Extraction, Treatment, and Recharge System, 100%
Submittal ("Final Groundwater Design") dated March 1996, estimates
that the Cascade Tray Air Stripper facility will generate only
0.035 Ibs of VOCs per day, which is much less than the county
standard. However, the NGB, upon conducting a cost analysis of
various RACT options and assessing community opinion at public
meetings concerning their desire that RACT be implemented for
remediation systems at the TIAA site, found that vapor-phase GAG
emission controls could be implemented at a reasonable cost. This
ESD#1 allows the NGB to voluntarily incorporate GAC air emission
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controls into its Final Groundwater Design. The NGB may elect to
remove these controls in the future as allowed by federal, state
and county law and rules.
2 . Treated Water Standards for Rein-lection
The 1988 ROD is not explicitly clear on the
treatment requirements for groundwater that is treated and then
reinjected via groundwater injection wells back into the regional
aquifer. This ESD#1 clarifies the 1988 ROD treated water
requirement to state that the treated water standards for water
intended to be reinjected back into the regional aquifer shall be
Federal Safe Drinking Water Act MCLs. The use of MCLs for the
treated water standard for reinjection is compliant with ARARs.
IV. SUPPORT AGENCY COMMENTS
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). On behalf of the state, the Arizona Department of
Environmental Quality (ADEQ) and the Arizona Department of Water
Resources (ADWR) provided comments on the proposed ESD#1.
Both ADWR and ADEQ comment letters focused on EPA's
justification for changing the treated water end use from municipal
drinking water to reinjection. Although both state agencies
agreed with the substance of this change, they suggested that EPA
emphasize that the primary factors for the change in favor of
reinjection consist of: (1) institutional barriers to municipal
use; (2) reinjection had previous EPA analysis and public comment
in feasibility study and proposed plan for the 1988 ROD; (3)
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reinjection is ARAR compliant. The State agencies went on to state
that City of Tucson's Proposition 200 does not qualify as an ARAR
and therefore should not be referenced as a primary reason for this
change in the ROD. EPA agrees with these state comments and
modified Section III of this BSD accordingly. The comment letters
from ADWR and ADEQ on the proposed ESD#1 are included in the
Administrative Record.
V. STATUTORY DETERMINATIONS
Considering the new information that has been developed since
the 1988 ROD and the changes that have been made to the selected
groundwater remedy for Area B-west required by this ESD#1, EPA
believes that the groundwater remedy for Area B-west of the TIAA
site will remain protective of human health and the environment,
and will continue to comply with federal and state requirements
that are applicable or relevant and appropriate to this remedial
action. .EPA also believes the Area B-west remedy will continue to
be cost-effective. In addition, the proposed 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#1 are significant,
but none of the proposed changes fundamentally change the remedy.
VI. PUBLIC PARTICIPATION ACTIVITIES
Pursuant to 40 C.F.R. Section 300.435(c)(2)(i), a formal
public comment period is not required for an BSD. However, EPA,
recognizing the high degree of community interest in site
activities, established a public comment period of thirty (30)
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calendar days to obtain written comments on the proposed ESD#1.
The comment period began on December 20, 1996 and closed on January
20, 1997. A newspaper advertisement was placed in local Tucson
newspaper, the Arizona Daily Star, on December 20, 1996 announcing
the availability of the proposed ESD#1 and the public comment
period. In order to promote additional public participation, EPA
presented the key components of this BSD during the June 19, 1996
and the January 15, 1997 Unified Community Advisory Board (UCAB)
meetings. UCAB is an on-going monthly community forum on TIAA site
issues. EPA received two comment letters from the State of Arizona
as described in Section IV. No written comment letters were
received by EPA from the public. Community relations activities to
support this final ESDtfl are set at 40 C.F.R. Section
300.435(c) (2) (ii) .
Upon EPA signature on this, final ESD#1, EPA will again publish
in the Arizona Daily Star newspaper a notice that describes the
final ESD#1 and announces its availability for review. In
accordance with 40 C.F.R. Section 300 .435 (c) (2) (i) , this final
ESD#1 and the documents that support the changes and clarifications
herein will be contained in the Administrative Record for the 1988
ROD prior to the commencement of operation of the groundwater
remedy for Area B-west.
- f-7
Keith Takata, Director Date
Superfund Division
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FIGURE i
Tucson International Airport Area Superfund Sitq
Drexel Road
s AREA
\ D
V
Air National
ucson
International |
Los Reales Road!
San Xavler
Indian
Reservation
i Hughes Access Roa
Approximate Scale
(in miles)
Suggested Superfund Site Boundaries
Approximate areas of
groundwater concentrations
y of 5 ppb TCE or greater*
"Indicates identified area of contamination prior to the start of cleanup; ongoing cleanup programs have markedly
reduced the area of contanvnation.
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Page 1
12/10/96
Attachment 1
Tucson International Airport Area
Area A t Area B Gcounduater OU
Tucson, Arizona
*** Draft Administrative Record Index *•*
DOC *
AR
*
DATE
yy/mm/dd
AUTHOR
ADDRESSEE
SUBJECT
FOIA
CBI
DISC
TYPES/ACTIVITIES
DESCRIPTORS
CONTRACT
INFO
0229-91746 00-001 94/09/20 Gary Hinkle
US Air FUILU
Charles M.CUIn
City of Tucson, AZ -
Tucson Water
Ltr: Describes cleanup (pump t
treat) system for TCE-
contamlnated groundwater In
Area B
01,23,24.60,66, .
0229-91747 00-002 94/10/19 Charles HcClaln
City of Tucson, AZ
Tucson Water
0229-91748 00-003 94/11/01 Gary Hlnkle
us Air Force
0229-91744 OD-004 94/12/09 City of Tucson, AZ
Gary Hlnkle
US Air Force
Ltr: Tucson Water nil I not
accept treated TCE groundwater
into potable water system
Craig Cooper Ltn Connunity groups oppose
Environmental Protection disposal of TCE-contamlnated
Agency - Region 9 groundwater Into Tucson
potable water system t ROD
Bmendncnt Is requested w/o
attchs
Proposition 200 (aka Water
Consumer Protection Act) •
amended chapter 27 of Tucson
code
01,24.68.66. , .
23.24.01.31.67,82.66
81.66.23. , . .
0229-00573 00-005 95/03/00 ERH-Ucit, Inc
022/01068 OD-006 96/03/00 ERH-West, Inc
US Air National Guard
US Air National Guard
Draft final preliminary design 7
rpt for groundwater, w/TL fr N
Grlnnt to C Cooper 5/11/95
Design for groundwater
extraction, treatment It
recharge system, 100X
subtnittal, w/TL fr J Quinn to
M Grimm 3/15/96
23,68,81,86,04.24.82
23,07.65.53. . .
0229-01252 00-007 96/06/19 Craig Cooper
Unified connunity advisory
67,31,82,66,83.23,28
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12/10/96
Tucson International Airport Area
Area A I Area B Groundwater OU
Tucson, Arizona
•'* Draft Administrative Record Index ***
DOC
tt
AR n
DATE
yy/mn/dd
AUTHOR
ADDRESSEE
SUBJECT
FOIA
CBI
DISC
TYPES/ACTIVITIES
DESCRIPTORS
CONTRACT
INFO
Environmental Protection
Agency - Region 9
0229-01292 OD-OOS 96/12/00 Craig Cooper
Environmental Protection
Agency - Region 9
0229-91749 00-009 96/12/10 Craig Cooper Addressee List
Environmental Protection
Agency - Region 9
0229-91745 00-010 96/12/20 Environmental Protection Arizona Dally Star
Agency - Region 9
board (UCAB) mtg agenda, final
mtg minute* I key point
s urinary
Proposed explanation of
significant differences (ESO)
*1 to 1988 grounduater ROD
w/note fr C Cooper & w/J
attchs
Memo: Changes to 1988
groundwater ROD re Air Hatl
Guard project area
Public notice: Availability of
explanation of significant
differences (ESD) #1
82,81,24.45,53.04.31
03,82,45,68,23.24,81
11.66,82.81.23.31,45
No. of Records: 10
\arlegal_cont.rpt
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Attachment #2
Overview of the Treated Water Cleanup Levels and In-Situ
Groundwater Cleanup Levels required by the Tucson International
Airport Area (TIAA) Super fund site August 1988 Record of Decision
(ROD) as clarified by Explanation of Significant Differences
(ESDttl).
"Treated Water" means water exiting a groundwater treatment
system for Area A or Area B required by the 1988 ROD.
"In-situ Groundwater" means groundwater located in the regional
aquifer within the boundaries of Area A or Area B as defined in
the 1988 ROD.
"Safe Drinking Water Act (SDWA)" means the federal Safe Drinking
Water Act.
"parts per billion (ppb)" means micrograms per liter.
"Maximum Contaminant Level" or "MCL" means MCL as defined in the
SDWA, and the specific values have been promulgated as final,
primary maximum contaminant levels pursuant to the SDWA as of
June 4, 1991.
"TCE" means trichloroethylene.
TREATED WATER
IN-SITU GROUNDWATER
Treatment Goal for water
intended for direct drinking
water usage: The goal is to
remove contamination from
groundwater extracted from the
regional aquifer until an
overall excess cancer risk
level (for all contaminants
combined) of 1 in 1 million is
achieved.
Treatment Goal; The treatment
goal for in-situ groundwater
is to restore contaminated
areas of the regional aquifer
back drinking water quality.
Required Cleanup Levels:
The required treated water
standards all Site
contaminants are MCLs. The
TCE standard is lowered to 1.5
ppb TCE in any treated water
intended for direct drinking
water usage.
Reoruired Cleanup Levels:
The required in-situ
groundwater cleanup levels for
all Site contaminants are
MCLs.
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Attachment #3
Overview of the modifications by Explanation of Significant
Differences (ESD#1) to the Tucson International Airport Area
(TIAA) Superfund site August 1988 Record of Decision (ROD).
The Original 1988 ROD
Groundwater Clean-up Plan for
Area B-West
(Air National Guard Base)
- Groundwater Extraction;:
Pump from groundwater
extraction wells in the upper
divided regional aquifer to
restore aquifer to MCLs and
prevent migration of
groundwater contamination.
- Groundwater Treatment;
Treat extracted groundwater
via packed column aeration air
stripping technology.
- Treated Groundwater Enduse;
Treated water will be fed
directly into the municipal
water distribution system.
- Air Emission Controls: None
required.
The Modified Clean-up Plan for
Area B-West as Required by
ESD#1
- Groundwater Extraction: same
as 1988 ROD.
- Groundwater Treatment: Treat
extracted groundwater via
cascade tray air stripping
technology.
- Treated Groundwater Enduse:
Treated water will be
reinjected via injection wells
back into the upper divided
regional aquifer.
- Air Emission Controls;
Capture airborne volatile
organic compound contaminants
using granular activated
carbon controls. [Voluntary
Action]
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SFUND RECORDS CTR
0229-01006
XR0004
February 12, 1997
TO: Keith Takata, Director
Superfund Division
VIA: Martin PesareB^T Office of Regional Counsel ^/TU/^l
Mike Montgomery, Chief, CA & AZ Cleanup Section
John Kemmerer, Acting Chief, Superfund Enf. Branc
Dan Opalski, Chief, Federal Facilities Compliance' Branch
FR: Craig Cooper, Remedial Project Manager, SFD7-1 £
RE: Tucson International Airport Area Superfund Site
Final ESD#1 to 1988 ROD
Attached for your signature is the final ESD#l to EPA's 1988 ROD
for groundwater cleanup at the Tucson Airport site. This BSD
concerns changes to the groundwater remedy at the Air Guard
facility only.
The primary change to the Air Guard remedy concerns switching the
enduse of the treated water from municipal to reinjection. More
minor changes described in the BSD include changing the air
stripping technology to cascade trays, allowing voluntary use of
GAG air controls, and clarifying that the treated water must meet
MCLs prior to reinjection.
Please call me at 520-628-6722 with any questions..
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