[Federal Register Volume 68, Number 40 (Friday, February 28, 2003)]
[Proposed Rules]
[Pages 9615-9621]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-4509]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 300

[FRL-7455-2]


National Oil and Hazardous Substances Pollution Contingency Plan; 
National Priorities List

AGENCY: Environmental Protection Agency.

ACTION: Notice of intent for partial deletion of a portion of the South 
Indian Bend Wash Site from the National Priorities List.

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SUMMARY: The Environmental Protection Agency (EPA) Region IX announces 
its intent to delete a portion of the South Indian Bend Wash (SIBW) 
Site located in Tempe, Maricopa County, Arizona, from the National 
Priorities List (NPL) and requests public comment on this action. The 
NPL constitutes Appendix B to the National Oil and Hazardous Substances 
Pollution Contingency Plan (NCP), 40 CFR Part 300, which EPA 
promulgated pursuant to Section 105 of the Comprehensive Environmental 
Response, Compensation, and Liability Act (CERCLA).

DATES: EPA will accept comments concerning its proposal for partial 
deletion for thirty (30) days after publication of this document in the 
Federal Register and a newspaper of record.

ADDRESSES: Comments may be mailed to: Melissa Pennington, Superfund 
Remedial Project Manager, U.S. EPA, Region IX [SFD-8-2], 75 Hawthorne 
Street, San Francisco, CA 94105, (415) 972-3153.
    Information Repositories: Comprehensive information on the SIBW 
Site as well as information specific to this proposed partial deletion 
is available for review at EPA's Region IX office in San Francisco, CA 
and at the information repositories listed below. There are three 
Administrative Record files for the SIBW Site: one for the 1993 Record 
of Decision for VOCs in the Vadose Zone; one for the 1998 Record of 
Decision for VOCs in Groundwater; and one for the Plug-in Determination 
issued in January 2002. All three Administrative Record files and the 
Deletion Docket for this partial deletion are maintained at EPA Region 
IX's Regional Office Superfund Records Center and the Tempe Public 
Library. EPA's Superfund Records Center is located at 95 Hawthorne 
Street (Suite 403S), San Francisco, CA 94105 and the hours of operation 
are 8-5 p.m., Monday-Friday. The Records Center

[[Page 9616]]

staff can be reached at (415) 536-2000. The location of the other 
information repository where the Deletion Docket is available for 
public review is: Tempe Public Library (South Area), 3500 South Rural 
Road, Tempe, AZ 85282.

FOR FURTHER INFORMATION CONTACT: Melissa Pennington (415) 972-3153.

SUPPLEMENTARY INFORMATION: This partial deletion of the SIBW Site is 
proposed in accordance with 40 CFR 300.425(e) and the Notice of Policy 
Change: Partial Deletion of Sites Listed on the National Priorities 
List. 60 FR 55466 (Nov. 1, 1995).
    In July 2002, the City of Tempe (the City) submitted a petition to 
EPA for Partial Deletion of a portion of the SIBW Site from the NPL. To 
help facilitate an ongoing redevelopment project, the City requested 
that EPA delete a 200-acre property known as the McClintock/Rio Salado 
Brownfield Redevelopment Area (Redevelopment Area). This proposal for 
partial deletion from the SIBW NPL Site pertains to the former Allstate 
Mine Supply Subsite, the Maricopa County Landfill, the Old Tempe 
Landfill, the Resources Reclamation Corporation of America Landfill, 
the First Street Landfill and the Bennett Family Trust Landfill, which 
properties comprise that portion of the Redevelopment Area presently 
part of the SIBW NPL Site. These properties subject to this proposal 
for partial deletion are collectively referred to hereafter as the 
``SIBW Landfill Area''. The location of the SIBW Landfill Area is shown 
on Figure 1. Both Figures 1 and 2 are available for viewing in the 
Deletion Docket which is maintained at EPA Region IX's Regional Office 
Superfund Records Center and the Tempe Public Library (details below).
    This proposal for partial deletion pertains to all of the soils in 
the SIBW Landfill Area and a majority of the groundwater underlying the 
SIBW Landfill Area hereinafter referred to as the ``SIBW Deletion 
Area''. The groundwater included in the SIBW Deletion Area is that 
groundwater with concentrations of trichloroethylene (TCE) less than 5 
parts per billion (ppb). Based on existing data, the groundwater in the 
middle alluvial unit with concentrations of TCE less than 5 ppb is 
represented as that portion of the groundwater underlying the SIBW 
Landfill Area that is not within the 5 ppb TCE contour line as depicted 
on Figure 2 (available for viewing in the Deletion Docket). Once the 
partial deletion is effective, the only area remaining on the NPL north 
of Rio Salado Parkway will be the extent of groundwater contamination 
in the middle alluvial unit above 5 ppb TCE. This area is shown on 
Figure 2 (available for viewing in the Deletion Docket) as the overlap 
of the southeast corner of the SIBW Landfill Area and the 5 ppb TCE 
contour. This overlap has been estimated to cover approximately 7.4 
acres.
    Additional data may be obtained prior to the final Notice of 
Deletion that would allow for refinement of the definition of extent of 
groundwater contamination exceeding 5 ppb TCE depicted on Figure 2 
(available for viewing in the Deletion Docket). Such information would 
then be set out in the final Notice of Deletion.
    The SIBW site was added to the NPL because of widespread 
groundwater contamination caused by numerous facilities within the City 
of Tempe. The contaminants of concern (COCs) are volatile organic 
compounds (VOCs), primarily TCE and tetrachloroethylene (PCE). In order 
to efficiently manage the site, SIBW was divided into two operable 
units: a soil operable unit and a groundwater operable unit. In 1993, 
EPA issued a Record of Decision for VOCs in the Vadose Zone (1993 Soils 
ROD) at SIBW which required investigation of several facilities 
referred to as subsites. If the subsite investigations indicated that 
any subsite posed a continuing threat to groundwater or indoor air 
quality, then Soil Vapor Extraction (SVE) would be required. To date, 
EPA has completed or has overseen the investigations of approximately 
twelve subsites. Among the twelve subsites, SVE was required at one 
subsite in accordance with the (1993 Soils ROD), SVE was voluntarily 
conducted by the responsible parties at two of the subsites, SVE was 
not required at seven of the subsites, and the remaining subsites are 
still under investigation. None of the subsites still under 
investigation are part of this partial deletion.
    EPA has evaluated all existing data regarding the SIBW Landfills 
and concluded that the COCs are not present at the five landfills at 
levels which pose a continuing threat to groundwater or indoor air 
quality. The Focused Remedial Investigation Report for the Allstate 
Subsite concluded that this subsite does not pose a continuing threat 
to groundwater or indoor air quality. Therefore, in accordance with the 
1993 Soils ROD, EPA has determined that these subsites do not pose a 
threat to groundwater and that no further federal CERCLA response 
actions are required at the SIBW Landfill Area with respect to the 
groundwater.
    The focus of EPA's listing of this Site has been on the groundwater 
contamination and the sources of groundwater contamination. EPA did not 
intend to address all areas within the SIBW study area that might be 
contaminated, only those directly linked to the groundwater 
contamination. As a result of EPA's investigation, EPA has also 
determined that the contaminated levels in soil at these subsites do 
not pose a threat to indoor air. However, no determination has been 
made as to whether these properties are suitable for unrestricted uses. 
Any attempt to develop the SIBW Landfill Area should be coordinated 
with the Arizona Department of Environmental Quality (ADEQ), as well as 
other appropriate state and local agencies, to ensure that non-CERCLA 
environmental issues associated with these properties are fully 
investigated and addressed prior to development.
    There are three separate plumes of contaminated groundwater 
(eastern, central and western), resulting from former disposal 
practices at various SIBW subsites. The remedies selected for the SIBW 
groundwater plumes are: monitored natural attenuation in the central 
and eastern plumes and extraction and treatment via air stripping in 
the western plume. The groundwater operable unit and the remaining 
subsites of the soil operable unit will remain on the NPL. This 
proposal to delete the SIBW Deletion Area from the SIBW NPL Site is 
based on the determination by EPA and ADEQ that all appropriate federal 
actions under CERCLA with regard to the SIBW Deletion Area have been 
completed. Based on EPA's discussions with ADEQ, it has also been 
determined that ADEQ's Voluntary Remediation Program is an option for 
addressing any remaining environmental issues at the SIBW Landfill 
Area.

Table of Contents

I. Introduction
II. NPL Deletion Criteria
III. Deletion Procedures
IV. Basis for Intended Partial Site Deletion

I. Introduction

    The United States Environmental Protection Agency (EPA) Region IX 
announces its intent to delete a portion of the South Indian Bend Wash 
(SIBW) Site located in Tempe, Maricopa County, Arizona, from the 
National Priorities List (NPL) and requests public comment on this 
action. This proposal for partial deletion from the SIBW NPL Site 
pertains to the former Allstate Mine Supply Subsite, the Maricopa 
County Landfill, the Old Tempe Landfill, the

[[Page 9617]]

Resources Reclamation Corporation of America Landfill, the First Street 
Landfill and the Bennett Family Trust Landfill. These properties 
subject to this proposal for partial deletion are collectively referred 
to hereafter as the ``SIBW Landfill Area''. The location of the SIBW 
Landfill Area is shown on Figure 1 (available for viewing in the 
Deletion Docket).
    This proposal for partial deletion pertains to all of the soils in 
the SIBW Landfill Area and a majority of the groundwater underlying the 
SIBW Landfill Area hereinafter referred to as the ``SIBW Deletion 
Area'.
    The NPL constitutes appendix B to the National Oil and Hazardous 
Substances Pollution Contingency Plan (NCP), 40 CFR part 300, which EPA 
promulgated pursuant to Section 105 of the Comprehensive Environmental 
Response, Compensation, and Liability Act (CERCLA). This partial 
deletion of the SIBW Site is proposed in accordance with 40 CFR 
300.425(e) and the Notice of Policy Change: Partial Deletion of Sites 
Listed on the National Priorities List. 60 FR 55466 (Nov. 1, 1995). 
This guidance allows EPA to delete portions of a site, including 
deletions by media.
    The National Priorities List (NPL) is a list, maintained by EPA, of 
sites that EPA has determined present a significant risk to human 
health, welfare, or the environment. This proposal for partial deletion 
from the SIBW NPL Site pertains to the SIBW Deletion Area defined in 
the Summary section above (page 2). The location of the SIBW Landfill 
Area is shown on Figure 1 and the area of groundwater included within 
the SIBW Deletion Area is shown on Figure 2. Figures 1 and 2 are 
available for viewing in the Deletion Docket.
    The SIBW study area covers approximately three square miles in 
Tempe, Arizona. The Site consists of groundwater contaminated with VOCs 
(primarily TCE and PCE) and soil contamination at the facilities on the 
surface that have contributed to or are contributing to the groundwater 
contamination. Groundwater at the Site is present in three separated 
levels or layers. These layers are referred to as the Upper, Middle, 
and Lower Aquifers. The groundwater contamination is present as three 
separate plumes known as the western plume, eastern plume and central 
plume. Land use in the vicinity of the Site includes residential, 
industrial/commercial, agricultural, public and private recreational 
(parks, golf courses, playing fields, etc.), undeveloped open space, 
and waterways.
    There have been two Records of Decision (RODs) issued for SIBW to 
address VOC contamination at the Site, one for soil and one for 
groundwater. The soils ROD required Soil Vapor Extraction (SVE) at 
areas within SIBW (known as subsites) that meet specific criteria which 
are used to assess whether VOC levels at a subsite pose a threat to 
groundwater and ambient air. The soils ROD was issued in September 
1993. The groundwater ROD required Monitored Natural Attenuation in the 
central and eastern plumes and extraction and treatment of the western 
plume. The groundwater ROD was issued in September 1998.
    The approximate boundaries for the SIBW Landfill Area are the Rio 
Salado Parkway, which forms a portion of the boundary to the south; the 
Salt River to the north; Perry Lane, which makes up most of the western 
boundary; and the eastern boundary is between Rockford Drive and River 
Drive. However, the actual boundaries are the boundaries of the SIBW 
Landfill Area as depicted on Figure 1 (available for viewing in the 
Deletion Docket). The boundaries of the SIBW Deletion Area are defined 
as the boundaries of the SIBW Landfill Area (described above) with the 
exception of the area of groundwater contamination in the middle 
alluvial unit above 5 ppb TCE. This area is shown on Figure 2 
(available for viewing in the Deletion Docket) as the overlap of the 
southeast corner of the SIBW Landfill Area and the 5 ppb TCE contour. 
This overlap has been estimated to cover approximately 7.4 acres.
    In July 2002, the city of Tempe (the City) submitted a petition to 
EPA for Partial Deletion of a portion of the SIBW Site from the NPL. To 
help facilitate an ongoing redevelopment project, the City requested 
that EPA delete a 200-acre property known as the McClintock/Rio Salado 
Brownfield Redevelopment Area (Redevelopment Area). EPA is proposing 
only the SIBW Deletion Area, as defined in the Summary section above 
(page 2), for deletion from the NPL Site (See Figure 1 which is 
available for viewing in the Deletion Docket). This is because EPA 
considers only a portion of the entire 200-acre Redevelopment Area to 
be part of the SIBW NPL Site. The SIBW NPL Site is defined as the 
groundwater plumes contaminated with VOCs and the facilities on the 
surface that have contributed to or are contributing contamination to 
the groundwater plumes.
    The SIBW Landfill Area, which encompasses the SIBW Landfills and 
the Allstate Subsite, has been thoroughly investigated. In October 
2001, a Focused Remedial Investigation Report (FRI Report) was prepared 
for the Allstate Subsite by EPA's contractor (CH2M Hill) and several 
documents have been prepared describing the conditions at the SIBW 
Landfills. In December 1993, ADEQ prepared a draft document entitled 
``Indian Bend Wash (South) Superfund Site, Tempe, Arizona, Evaluation 
of Landfills.'' In 1999, ADEQ contracted Roy F. Weston to evaluate the 
existing landfill information and to prepare a report. This document 
was entitled ``Review of Previous Site Characterization Work at Former 
Landfills''. These documents recommended additional work be performed 
before a decision could be made regarding remediation at the landfills. 
In December 2002, EPA's contractor compiled all of the existing 
landfill data into a technical memorandum. The main objective of this 
technical memorandum was to utilize data from the landfills as well as 
groundwater data that had been collected as part of the ongoing 
groundwater remedy at SIBW to assess whether the soil contamination in, 
beneath, and in the vicinity of the landfill sites has contributed to 
the VOC contamination in the groundwater plumes.
    For the purposes of this proposal, EPA has evaluated the 
conclusions regarding the Allstate Subsite in the Allstate FRI Report 
as well as the data and conclusions in CH2M Hill's December 2002 SIBW 
Landfill Sites Technical Memorandum. As a result, EPA has determined 
that the SIBW Landfill Area does not require soil remediation for 
protection of the groundwater in accordance with the 1993 Soils ROD. 
Therefore, no further federal CERCLA action is necessary for the SIBW 
Landfill Area to protect human health and the environment with respect 
to VOCs in soils contributing to the groundwater contamination. As 
indicated previously in this document, the 1993 Soils ROD addresses 
VOCs only. When placed on the NPL, the SIBW Site was defined as 
groundwater plumes contaminated with VOCs and the surface sources 
contributing to the VOC contamination in the groundwater. It was never 
EPA's intention that remediation of the SIBW site would include 
contaminants other than VOCs. Therefore, this proposed deletion does 
not draw any conclusions about the potential presence or absence of 
other contaminants in the SIBW Landfill Area. It is EPA's understanding 
that further investigation and remediation of the landfill properties 
will be conducted by the prospective developers prior to

[[Page 9618]]

redevelopment of the property. ADEQ is in agreement with this approach.
    This proposed deletion specifically addresses the soils at the SIBW 
Landfill Area and the groundwater beneath the SIBW Landfill Area with 
concentrations of TCE less than 5 ppb. Groundwater associated with the 
SIBW Site with concentrations of TCE greater than 5 ppb is being 
addressed as part of the remedial action at the SIBW Site. The plume 
south of the SIBW Landfill Area is known as the eastern plume. The 
remedial design for monitored natural attenuation in the eastern plume 
is being implemented by an SIBW potentially responsible party. Response 
activities for the SIBW groundwater plumes are not yet complete and 
therefore the groundwater operable unit will remain on the NPL. 
Similarly, the remaining SIBW subsites are not subject to this partial 
deletion.
    The NPL is a list, maintained by EPA, of sites that EPA has 
determined present a significant risk to human health, welfare, or the 
environment. Sites on the NPL may be the subject of remedial actions 
financed by the Hazardous Substance Superfund (Fund). Pursuant to 40 
CFR 300.425(e) of the NCP, any site or portion of a site deleted from 
the NPL remains eligible for Fund-financed remedial actions if 
conditions at the site warrant such action.
    EPA will accept comments concerning its intent for partial deletion 
for thirty (30) days after publication of this notice in the Federal 
Register and a newspaper of record.

II. NPL Deletion Criteria

    The NCP establishes the criteria that EPA uses to delete sites from 
the NPL. In accordance with 40 CFR 300.425(e), sites may be deleted 
from the NPL where no further response is appropriate to protect human 
health or the environment. In making such a determination pursuant to 
40 CFR 300.425(e), EPA will consider, in consultation with the State, 
whether any of the following criteria have been met:
    A. Section 300.425(e)(1)(i). Responsible parties or other persons 
have implemented all appropriate response actions required; or
    B. Section 300.425(e)(1)(ii). All appropriate Fund-financed 
response under CERCLA has been implemented, and no further response 
action by responsible parties is appropriate; or
    C. Section 300.425(e)(1)(iii). The remedial investigation has shown 
that the release poses no significant threat to human health or the 
environment and, therefore, taking of remedial measures is not 
appropriate.
    Deletion of a portion of a site from the NPL does not preclude 
eligibility for subsequent Fund-financed actions at the area deleted if 
future site conditions warrant such actions. Section 300.425(e)(3) of 
the NCP provides that Fund-financed actions may be taken at sites that 
have been deleted from the NPL. A partial deletion of a site from the 
NPL does not affect or impede EPA's ability to conduct CERCLA response 
activities at areas not deleted and remaining on the NPL. In addition, 
deletion of a portion of a site from the NPL does not affect the 
liability of responsible parties or impede agency efforts to recover 
costs associated with response efforts.

III. Deletion Procedures

    Deletion of a portion of a site from the NPL does not itself 
create, alter, or revoke any person's rights or obligations. The NPL is 
designed primarily for informational purposes and to assist Agency 
management. The following procedures were followed for the proposed 
deletion of the SIBW Deletion Area from the SIBW NPL Site:
    (1) EPA received and evaluated a petition for partial deletion from 
the City of Tempe;
    (2) The State of Arizona through the Arizona Department of 
Environmental Quality pledged support for the partial deletion and 
encouraged EPA to proceed with the deletion process;
    (3) EPA preliminarily concurred with the recommendations for 
partial deletion and prepared the relevant documents;
    (4) Concurrent with this national Notice of Intent for Partial 
Deletion, a notice has been published in a newspaper of record and has 
been distributed to appropriate federal, State, and local officials, 
and other interested parties. These notices announce a thirty (30) day 
public comment period on the deletion package, which commences on the 
date of publication of this notice in the Federal Register and a 
newspaper of record.
    (5) EPA has made all relevant documents available at the 
information repositories listed previously.
    This Federal Register document, and a concurrent notice in a 
newspaper of record, announce the initiation of a thirty (30) day 
public comment period and the availability of the Notice of Intent for 
Partial Deletion. The public is asked to comment on EPA's proposal to 
delete the SIBW Deletion Area from the NPL. All critical documents 
needed to evaluate EPA's decision are included in the Deletion Docket 
and are available for review at the information repositories.
    Upon completion of the thirty (30) day public comment period, EPA 
will evaluate all comments received before issuing the final decision 
on the partial deletion. EPA will prepare a Responsiveness Summary for 
comments received during the public comment period and will address 
concerns presented in the comments. The Responsiveness Summary will be 
made available to the public at the information repositories listed 
previously. Members of the public are encouraged to contact EPA Region 
IX to obtain a copy of the Responsiveness Summary. If, after review of 
all public comments, EPA determines that the partial deletion from the 
NPL is still appropriate, EPA will publish a final notice of partial 
deletion in the Federal Register. Deletion of the SIBW Deletion Area 
does not actually occur until the final Notice of Partial Deletion is 
published in the Federal Register.

IV. Basis for Intended Partial Site Deletion

    The following provides EPA's rationale for deletion of the SIBW 
Deletion Area from the NPL and EPA's finding that the criteria in 40 
CFR 300.425(e) are satisfied.

Background

    The entire study area of the Indian Bend Wash Superfund Site (Site) 
covers approximately 13 square miles in Scottsdale and Tempe, Arizona. 
EPA divided the Site into two areas known as the Indian Bend Wash 
Area--North (NIBW) and the Indian Bend Wash Area--South (SIBW). EPA is 
proposing to delete a portion of the SIBW site only; all of the NIBW 
Site and most of the SIBW Site will remain on the NPL.
    As discussed below, there are numerous industrial facilities 
located within the boundaries of the Site study area. Up until the 
1970s, industrial solvents containing VOCs were typically disposed of 
directly onto the ground or in dry wells. These disposal practices, 
along with other releases, resulted in soil and groundwater 
contamination at various locations throughout the Site. The groundwater 
contamination at NIBW was discovered in 1981 when elevated levels of 
VOCs, including TCE, were found in drinking water wells. Further 
investigation of regional groundwater quality led to the discovery and 
characterization of the three SIBW groundwater contamination plumes 
(western, central and eastern). The unacceptable risks associated with 
the contamination at SIBW is based on exposure to groundwater 
contamination. There were no significant levels of inorganic 
contaminants found in the

[[Page 9619]]

groundwater. Therefore, all remedial actions required at the SIBW Site 
were intended to address VOCs in groundwater and VOCs in soils which 
could contribute to groundwater contamination.
    EPA and the State of Arizona have been involved in investigations 
and cleanup activities at the Site since the initial discovery of VOCs 
in the groundwater in 1981. The Site, including both NIBW and SIBW, was 
placed on EPA's NPL in 1983. On September 27, 1993, EPA issued a Record 
of Decision for VOCs in the Vadose Zone (the 1993 Soils ROD). This ROD 
selected soil vapor extraction (SVE) as the remedy for VOCs in soils at 
SIBW and is discussed in more detail below. EPA also characterized 
contamination in groundwater and issued a second Record of Decision on 
September 30, 1998 for VOCs in groundwater at SIBW. The groundwater ROD 
is not discussed in detail in this document.
    The surface portion of the SIBW Site is divided into many small 
isolated locations where soil contaminated with VOCs was expected to be 
present. These locations are known as subsites. The 1993 Soils ROD 
utilized an approach called ``Plug-in,'' whereby the ROD did not 
directly apply the SVE remedy to any particular subsite. Rather, the 
ROD established criteria that EPA uses to determine whether pre-defined 
conditions exist at any given subsite thereby indicating that a subsite 
needs to be remediated using SVE. Each individual subsite had to be 
evaluated by EPA to determine whether it ``Plugged-in'' to the SVE 
remedy. These evaluations are based on the data collected at each of 
the subsites following issuance of the ROD. Implementation of SVE is 
required for subsites that ``Plug-in,'' or meet certain criteria, in 
accordance with the 1993 Soils ROD.
    The risks associated with VOCs in the Vadose Zone at the SIBW 
Landfills and other SIBW subsites were risks solely attributable to the 
potential for VOCs in soils to enter the groundwater or the air (See 
Interim Risk Assessment, Operable Unit Feasibility Study, VOCs in 
Vadose Zone, Appendix A, June 1993). In the Interim Risk Assessment, 
direct contact and ingestion of VOCs in soil were not considered 
complete exposure pathways because surface VOCs would likely volatilize 
before direct contact or ingestion could occur. Therefore, there are no 
risks associated with direct human exposure to VOCs in soils. The FRI 
Report for the Allstate Subsite and the SIBW Landfills Technical 
Memorandum evaluated whether or not VOCs in the Vadose Zone had the 
potential to impact groundwater or air. If a particular subsite does 
not meet the plug-in criteria identified in the 1993 ROD, the risks 
posed by the residual VOC contamination, if any, do not warrant further 
action.
    At the time that the 1993 ROD was issued at SIBW, approximately 
thirty facilities were considered potential source areas for VOC 
contamination in the groundwater. Five of these facilities had already 
been issued unilateral orders to complete site investigations. These 
five facilities were: DCE Circuits, Eldon Drapery, IMC Magnetics, 
Prestige Cleaners, and Unitog Cintas. Following additional screening, 
it was determined that investigations should also be conducted at 
Arizona Public Service (APS), Circuit Express, Allstate Mine Supply, 
Desert Sportswear, Cerprobe, Service and Sales, and the City of Tempe 
Right-of-Way.
    In February 1994, EPA issued a Plug-in Determination requiring 
implementation of SVE at the DCE Circuits Subsite. This work has been 
conducted with fund-lead money and is currently nearing completion. APS 
made the determination that SVE was appropriate at its site in lieu of 
conducting additional investigations. APS implemented SVE successfully 
at its subsite, and EPA approved its closure report in April of 2001, 
documenting that soil cleanup had been completed at the APS Subsite.
    In January 2002, EPA issued a Plug-in Determination that documented 
EPA's subsite-specific decision for the following seven SIBW subsites: 
Eldon; Circuit Express; Allstate Mine Supply; Desert Sportswear; 
Cerprobe; Service and Sales; and City of Tempe Right-of-Way. In the 
January 2002 Plug-in Determination, EPA concluded that all seven 
subsites fall within the Remedy Profile defined in the 1993 Soils ROD 
and that the subsites contain VOCs in soils at concentrations that do 
not exceed the Plug-In Criteria. Therefore, SVE was not required for 
any of these subsites.
    The remaining SIBW subsites (IMC Magnetics, Prestige Drapery, and 
Unitog) are still being evaluated. EPA will address these subsites in 
future Plug-in Determinations.

Current Surface Conditions at the SIBW Deletion Area

    The Allstate Subsite is located at 1926 East First Street, Tempe, 
Arizona. It is also within the footprint of the Maricopa County 
Landfill discussed below. Prior to 1963, the property was vacant and 
undisturbed.
    From 1963 to 1976, the property was used in a gravel sorting 
operation and construction equipment and/or dumpsters became noticeable 
onsite. During this timeframe, the property served as a storage yard 
for A&B Enterprises (A&B). A&B was an operation that repaired garbage 
dumpsters. The repairs included painting, welding, and use of paint 
thinners.
    Beginning in approximately April 1976, Allstate Mine Supply, Inc. 
and Canyon State Chemical, Inc. used this property to blend soaps, 
solvents, and other chemicals into finished products to be sold to 
clients. The products were ``specialty cleaning products'' which are 
made by compounding liquid raw materials (chemicals) onsite. The 
compounding, storing and shipping of raw materials and finished 
products occurs in 55-gallon drums.
    EPA's FRI Report for the Allstate Mine Supply Subsite (Allstate 
FRI) found that VOCs are present in the soil vapor at the Allstate 
Subsite to a depth of approximately 43 feet below ground surface (bgs). 
Although as many as 10 VOCs were detected at the subsite, only 1,1,1-
TCA and PCE were consistently present in both shallow and deep samples. 
Total xylenes were detected at depth in all three sampling events in 
1998 and the 1999 sampling event. The maximum concentrations of these 
contaminants are as follows: PCE at 28 [mu]g/L, 1,1,1-TCA at 210 [mu]g/
L, and total xylenes at 88 [mu]g/L. In 1988, 1990 and 1994, shallow 
soil vapor data were collected for this subsite. Three sampling events 
were conducted in 1998 (August, September and November) and one 
sampling event was conducted in July 1999 from one soil vapor 
monitoring well (SVWM-6). Both shallow and deep soil vapor samples were 
collected. The soil vapor data show that PCE appears to persist through 
time and throughout the length of the vadose zone. 1,1,1-TCA and 1,1-
DCE appear to decrease with time and depth in the vadose zone. Total 
xylenes are at the highest concentrations at 43 feet bgs and appear to 
be decreasing over time. The levels of VOCs at the Allstate Subsite 
were not high enough to cause the subsite to Plug-in to the 1993 Soils 
ROD.
    The landfill properties are located along the north side of Rio 
Salado Parkway approximately one quarter of a mile east of McClintock 
Drive. The landfill property boundaries are shown on Figure 1 
(available for viewing in the Deletion Docket). Since these landfills 
operated sometimes on top of one another, each landfill will be 
discussed separately. Since the state, county, and

[[Page 9620]]

local government agencies did not keep information on landfill 
activities until after the landfills were closed, little information is 
available. Most of the information available is from site investigation 
activities that began around 1988 as part of the SIBW Superfund Site 
investigation. Five landfills were operated on the property in the 
vicinity of the proposed redevelopment project in Tempe, Arizona. These 
landfills are: Maricopa County Landfill; Old Tempe Landfill; Resources 
Reclamation Corporation of America; First Street Landfill; and the 
Bennett Family Trust Landfill.
    The Maricopa County Landfill operated on the southwest portion of 
the landfill area properties and consisted of approximately 40 acres. 
The landfill has two distinct areas, a northern portion and a southern 
portion, based on apparent differences in fill material, time of 
emplacement, and soil vapor sampling results.
    A number of buildings were constructed on the southern portion of 
the landfill. None of the buildings were associated with the landfill 
operations. The buildings housed many industrial businesses, most 
notably the former Allstate Mine Supply. The Allstate Subsite was 
investigated as a separate and distinct subsite of SIBW as discussed 
above.
    The Old Tempe Landfill was located on the northeast corner of the 
landfill properties and consisted of approximately 11.5 acres. This 
landfill operated between 1971 and 1977, prior to which it was a gravel 
quarry. Conflicting information exists regarding the operating 
timeframe of this landfill. According to various property owners in the 
area, the landfill was operated as a municipal landfill by the cities 
of Tempe, Mesa, Phoenix, and Scottsdale from 1968 to 1979. The landfill 
primarily accepted solid waste; however, liquid and/or hazardous wastes 
may also have been accepted, although never verified. Resources 
Reclamation Corporation of America (RRCA), discussed below, purchased 
the property and continued the municipal landfill operations from 1978 
to 1982.
    The RRCA property totaled approximately 104 acres and included the 
area of the First Street Landfill, the Old Tempe Landfill, and adjacent 
parcels in the northwest corner of the landfill properties. The 
landfill accepted demolition debris, municipal solid wastes, and 
recyclable material, including metals, glass, and paper from the Cities 
of Tempe and Mesa, Arizona and reportedly did not accept any liquid or 
hazardous wastes. Additionally, RRCA was supposedly producing 
combustible materials for fuel cubes (refuse-derived fuel) from non-
recyclable products received at the landfill. RRCA disposed of the 
wastes over the area of the Old Tempe Landfill. The First Street 
Landfill property consisted of approximately 80 acres and included the 
area of the Old Tempe Landfill. The First Street Landfill accepted 
demolition debris and was to accept only inert materials such as dirt, 
concrete, and asphalt. Wood and uncontained refuse was also allowed if 
it was buried above the historical high water level.
    The Bennett Family Trust Landfill is located adjacent to the First 
Street Landfill and is comprised of approximately seven acres. Little 
information is available for this property. The Bennett Family Trust 
obtained the property in the 1970s and used an onsite pit for storage 
of automobiles related to their scrap yard. The pit was susceptible to 
flooding, so the Bennetts decided to fill the pit with clean material. 
Supposedly, the Bennetts observed every load of material used to fill 
the pit and did not allow wood, garbage, tires, or the like to be 
disposed of in the pit.
    The VOCs identified in the shallow soil-vapor within the SIBW 
Landfill Area include TCE, PCE and 1,1,1-TCA. These VOCs were 
identified because they were pervasive and persistent with respect to 
the three shallow soil vapor studies. In addition to the VOCs 
identified above, methane is also present in soil vapor at the SIBW 
Landfills. The methane concentrations are well below the lower 
explosive limit for methane, but still may cause a potential explosion 
risk if the gases build up inside of a structure.
    The highest concentrations of 1,1,1-TCA or PCE observed within the 
SIBW Landfill Area were associated with the Allstate Subsite. None of 
the VOCs of concern were detected in the soil beneath the SIBW 
Landfills at concentrations that suggest that there could be a 
continuing source contamination to the groundwater into the future. 
1,1,1-TCA contamination is present in soil vapor at concentrations 
ranging from 0.68 mg/L to 210 mg/L. The samples that contained the 
highest measured concentrations of 1,1,1-TCA are near the drywell on 
the former Allstate property. Data from SVMW-6, located at the former 
Allstate property, exhibited concentrations of 1,1,1-TCA that decreased 
with depth suggesting the 1,1,1-TCA source is above 30 feet bgs.
    Within the SIBW Landfill Area, PCE contamination is present in soil 
vapor at concentrations ranging from 0.24 mg/L to 30 mg/L. The samples 
that contained the highest measured concentrations of PCE are 
associated with the former Allstate property. PCE concentrations appear 
to be decreasing with depth, peak at approximately 30 feet bgs, and 
decrease below 30 feet bgs at the former Allstate property.
    TCE was observed only once within the SIBW Landfill Area in shallow 
soil vapor at a concentration of 0.55 mg/L in 1990. This TCE 
concentration was observed in SVMW-6 in 1998 and 1999 which is located 
at the former Allstate property. Unlike 1,1,1-TCA and PCE, the TCE 
concentrations do not appear to follow any identifiable pattern related 
to depth.
    The 1993 Soils ROD identified very specific criteria that 
determines whether or not soil remediation is required at SIBW 
subsites. The subsite must meet the following criteria in order for EPA 
to require soil remediation:
    (1) Present cancer risk (incremental risk) of more than one in one 
million to a person from both ingestion of VOCs in groundwater and 
inhalation of VOCs during other household uses of groundwater, such as 
showering, over a lifetime;
    (2) Present a cancer risk to a person of more than one in one 
million from inhalation of air above the soils at the subsite itself, 
over a lifetime;
    (3) Present a hazard index for non-cancer effects of more than one 
to a person from both ingestion of VOCs in groundwater and inhalation 
of VOCs during household uses of groundwater, over a lifetime;
    (4) Present a hazard index for non-cancer effects of more than one 
to a person from inhalation of air above the soils at the subsite 
itself, over a lifetime; and
    (5) Increase the concentration of VOCs in groundwater (incremental 
concentration) by an amount greater than the federal Maximum 
Contaminant Level (MCL) under the Safe Drinking Water Act.
    The maximum concentrations of 1,1,1-TCA, TCE and PCE in soil gas at 
the SIBW Landfill Area were obtained from sample points at the Allstate 
facility, which did not plug in to the 1993 soils ROD Remedy. 
Therefore, since the concentrations observed on the landfill properties 
are less than or equal to the concentrations observed at the Allstate 
Subsite, EPA has determined that the landfill properties would not meet 
any of the criteria listed above and therefore would not Plug-in to the 
1993 soils ROD Remedy.
    In conclusion, the concentration of VOCs detected in soil gas at 
the SIBW Landfill Area do not require any soil

[[Page 9621]]

remediation to be conducted under CERCLA.

Current Groundwater Conditions at the SIBW Deletion Area

    There are three separate plumes of contaminated groundwater 
(eastern, central and western), resulting from former disposal 
practices at various SIBW subsites. The primary contaminants of concern 
in the groundwater are VOCs, primarily TCE and PCE. EPA characterized 
contamination in groundwater and issued a Record of Decision on 
September 30, 1998 for VOCs in groundwater at SIBW (Groundwater ROD). 
The remedies selected for the SIBW groundwater plumes are: monitored 
natural attenuation in the central and eastern plumes and extraction 
and treatment via air stripping in the western plume. The cleanup 
levels for the SIBW plumes are based on the federal Safe Drinking Water 
Act Maximum Contaminant Levels (MCLs). The MCL for both TCE and PCE is 
5 parts per billion (ppb).
    The plume of groundwater with concentrations of TCE above 5 ppb in 
the vicinity of the SIBW Landfill Area is the eastern plume. This plume 
is located approximately 100 to 200 feet below ground surface (bgs) in 
a formation known as the Middle Alluvial Unit. The groundwater included 
in the SIBW Deletion Area is not part of the eastern plume and contains 
concentrations of TCE less than 5 ppb. Based on existing data, the 
groundwater in the middle alluvial unit with concentrations of TCE less 
than 5 ppb is represented as that portion of the groundwater underlying 
the SIBW Landfill Area that is not within the 5 ppb TCE contour line as 
depicted on Figure 2 (available for viewing in the Deletion Docket). 
Once the partial deletion is effective, the only area remaining on the 
NPL north of Rio Salado Parkway will be the extent of groundwater 
contamination in the middle alluvial unit above 5 ppb TCE. This area is 
shown on Figure 2 as the overlap of the southeast corner of the SIBW 
Landfill Area and the 5 ppb TCE contour. This overlap has been 
estimated to cover approximately 7.4 acres.
    Additional data may be obtained prior to the final Notice of 
Deletion that would allow for refinement of the definition of extent of 
groundwater which is presently above 5 ppb TCE depicted on Figure 2 
(available for viewing in the Deletion Docket). Such information would 
then be set out in the final Notice of Deletion.

Community Relations Activities

    Community interest in this site has been relatively low. With the 
exception of persons wanting to purchase property in the area, very few 
calls are received from citizens interested in activities at SIBW. EPA 
issued a fact sheet in February 2002 which described the January 2002 
Plug-in Determination for seven (7) SIBW Subsites including the 
Allstate Subsite. EPA has also conducted two formal public meetings. 
The first was on July 7, 1993 and was to present the proposed Soil 
Vapor Extraction Plug-in Remedy and the second was on September 24, 
1997 to present the proposed groundwater remedy.

Current Status

    The SIBW Landfill Area has been investigated and the plug-in 
analysis has been performed in accordance with the 1993 Soils ROD. As 
prescribed by the ROD, SVE remediation is not required and therefore, 
no further federal CERCLA action is necessary at the SIBW Landfill Area 
to protect human health and the environment with respect to VOCs in 
soils. However, any attempt to develop the SIBW Landfill Area should be 
coordinated with the Arizona Department of Environmental Quality 
(ADEQ), as well as other appropriate state and local agencies, to 
ensure that non-CERCLA environmental issues associated with these 
properties are fully investigated and addressed prior to development of 
the area. In accordance with 40 CFR 300.425(e)(1)(ii), EPA has 
determined that all appropriate Fund-financed response under CERCLA has 
been implemented in accordance with the 1993 Soils ROD, and no further 
response action by responsible parties is appropriate.
    While EPA does not believe that any future response actions at the 
SIBW Deletion Area will be needed with respect to CERCLA, if future 
conditions warrant such action, the proposed deletion area of the SIBW 
Site remains eligible for future Fund-financed response actions. In 
order to be eligible for future Fund-financed response actions the 
deleted portion of the SIBW site would either have to be re-listed on 
the NPL or an imminent and substantial threat would have to be 
documented that would warrant a CERCLA removal action. Furthermore, 
this partial deletion does not alter the status of the groundwater 
operable unit or the remaining subsites of the SIBW Site which are not 
proposed for deletion and remain on the NPL.
    In a letter dated July 2, 2002 the State of Arizona through its 
Department of Environmental Quality, has pledged its support for the 
partial deletion of this portion of the SIBW Site.

    Dated: February 14, 2003.
Keith Takata,
Acting Regional Administrator, Region IX.
[FR Doc. 03-4509 Filed 2-27-03; 8:45 am]
BILLING CODE 6560-50-P