Free Additional Attachments to Main Document - District Court of Arizona - Arizona

RECORDS

Phoenix-Goodyear Airport Area Super fund 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. selected in the

The State of Arizona concurred with the remedy 1989 ROD. In January 1991, EPA issued an

Explanation of Significant Difference (the 1991 BSD) which modified and clarified the 1989 ROD on five points. EPA now is modifying

the ROD a second 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 (March 8, 1990)), 300. 435 (c) (2) (ii) (55 Fed. Reg. 8666, 8852 is required to publish an BSD when

EPA

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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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 the 1989 ROD and how that remedy was modified by the 1991 ESD, a description of how this BSD affects the remedy originally selected by EPA in the 1989 ROD, and an explanation of why EPA is making these changes to the ROD. EPA is

issuing this second ESD to the 1989 ROD in order to take into 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,. portion of the site consists of the The northern

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

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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 GAG treatment requirement (or other similar effective technology) from the Subunit A groundwater 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 GAG treatment systems); (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 An explanation of when municipal end-use may still be considered is explained in Section III.E.
2 1

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 well(s) shall be treated as soon as possible by wellhead liquid-phase GAG 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 State of Arizona in (15) working day comment period for the accordance of Arizona with 40 on C.F.R. this Section ESD are

300.515(h)(3).

State

comments

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 BSD. However EPA, at its discretion, established a public

comment period of thirty (30) calendar days to obtain written or oral comments on the proposed BSD. period expired on April 1, 1993. This 30 calendar day comment

EPA held a public meeting in the A copy of the transcript from

City of Avondale on March 10, 1993.

the public meeting and copies of all written comments received by EPA have been placed in the administrative record,. considered all public comments on the proposed EPA carefully BSD prior to

issuance of this final BSD.

Community relations activities to

support this BSD 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 BSD. Additional

background information can be found in the 1989 ROD, the 1991 BSD and in the PGA Administrative Record. A. Site Background and Description The PGA site is located primarily in Goodyear, Arizona,

approximately seventeen (17) miles west of Phoenix in the western part of the Salt River Valley. A groundwater flow divide splits The

the site along Yuma Road into northern and southern portions.

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 PGA 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 site The

boundaries of the Phoenix-Goodyear Airport Superfund site. current land uses on and near the site are

agricultural,

industrial, and residential. In 1981, the Arizona Department of Health Services discovered that groundwater (ADHS)

in certain areas of the site was EPA and ADHS conducted

contaminated with solvents and chromium.

additional sampling of wells in 1982 and 1983 which revealed eighteen (18) wells contaminated with trichloroethylene (TCE). As a result, EPA added "Litchfield Airport the PGA site Area Superfund (originally Site") to listed the as the National

Priorities List (NPL) on September 8, 1983 (see Federal Register. Vol. 48, No. 175, p. 40671). Other hazardous substances found at

the PGA site include acetone, methyl ethyl ketone (MEK), 1,1,1trichloroethane (TCA), 1,1-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

groundwater11

(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 The

Section 16 Operable Unit was signed on September 29, 1987. designated remedy of a pump and treat system

for Subunit A A primary

groundwater has been operating since December 1989.

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 drinking 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 assistance of the Arizona

Department of Environmental Quality (ADEQ) , authorizes and oversees all clean-up activities at this Superfund site. B. Remedy Selected in the 1989 ROp 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 l of the 1987 ROD. ROD Remedy for Southern 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 Subunit B/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 for 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)

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)).
8

3

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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 portion is estimated to be from

soil remedy for the southern

$3,900,000 for a phased implementation, to $5,400,000 for a single phase implementation.

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. are required Vapor-phase GAG air emission controls The ROD

for the Subunit A groundwater remedy.

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 The

identifies the target area as that area where VOCs 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. $3,100,000. C. The 1991 ESP changes to the 1989 ROD The estimated present worth cost of the SVE system is

The BSD issued by EPA in January 1991 clarified and modified portions of EPA's September 1989 ROD. To the extent that the 1991 BSD differed from the ROD, the 1991 BSD supersedes the ROD. The 1991 BSD modified the ROD as follows: (1) The 1991 BSD revised the clean-up level for methyl ethyl ketone (MEK) in groundwater from 170 parts per billion (ppb) to 350

ppb;
(2) The 1991 BSD set a clean-up level for acetone in

groundwater at 700 ppb; * (3) The 1991 BSD 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 BSD, EPA defined these statements to

identify the soil remedy target area for the northern portion of the PGA site to consist of target areas B and C defined by all four circles in Figure 5-7 of the 1989 ROD; (4) The 1991 BSD clarified the role of soil excavation as a
10

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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 arid treatment may be required to remove residual contamination where soil vapor extraction is not effective." In the 1991 BSD, 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 BSD 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 Attachment #2 provides a condensed

this ESD are described below. overview of this ESD.

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Modifications to the ROD Remedy for PGA Site-North
A

- Vapor Treatment for the Soil Vapor Extraction System at the The ROD states that the contaminated soils at the PGA site-

Northern Portion of the Site

north (i.e. the Unidynamics area) will be treated by soil vapor extraction with vapor-phase GAG 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 as described in the ROD. All of Unidynamics1 design work plans and field activities were subject to EPA approval and oversight. In late 1991, Unidynamics installed two SVE for contaminant During this from the

extraction wells within the soil target area designated by the ROD. These SVE extraction wells were then tested concentration and pressure data in order to establish the final specifications needed to build the SVE remedy. testing, three (3) soil gas samples were collected

extracted vapor stream, and analyzed by EPA-approved test methods. The results are summarized below in Table 1.
TABLE1 PRELIMINARY CHARACTERIZATION QF SOIL VAPOR

Concentrations (ppm volume) Compound Acetone
MEK TCE

Sample SVEA-1
286

Sample SVEA-2
319

Sample SVEA-3
292

Average

299
1477

1327
436

1590
S49

1515
440

475
2251

Totals

2049

2458
12

2247

ppm = parts per million

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The data

shown

above were utilized

to make

preliminary

calculations to estimate GAG 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 extremely high rates, in excess of 4,000 Ibs. of GAC per day, which is much higher than the usage rates estimated at the time of the ROD. A 4,000 Ibs. per day GAC increase in the

usage rate would not only cause a significant

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 during SVE Pilot Testing, dated January 29, 1992 and revised March 13, 1992, Unidynamics evaluated several emissions control technologies for use during an SVE Pilot Testing

For additional information on this subject, see the administrative record for this BSD, document numbers 1, 2, and 3 . The index of documents for the administrative record for this BSD is provided in Attachment #4.
13

4

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Program5. recommended: extraction;

As a) and,

a

result

of use

this of SVE

evaluation, for

Unidynamics vapor of the

continued b) pilot

contaminant oxidation

testing

thermal

extracted contaminant vapors with wet scrubbing of the combustion by-products. natural gas In thermal oxidation, the soil vapor is heated, using or propane, to burn and destroy the vapor between

contaminants6.

Non-catalyzed

systems typically

operate

1400°F to 1600°F and destruction efficiency can be in excess of 99%. A wet scrubber unit is connected to the thermal oxidation The wet

unit to remove hydrochloric acid in the exhaust gas.

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%

To review a copy of this document, see the administrative record for this BSD, document number 12. For more information on thermal oxidation, see administrative record document number 4.
14
6

5

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can be achieved for the types of contaminants found in the soil target area at the Unidynaroics 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 accordance with the document entitled Proposed SVE Pilot Testing Program Description, dated October 1992 and revised

November 10, 1992, Unidynamics implemented a successful SVE/Thermal Oxidation pilot study during December 19927. concentrations The contaminant

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 2SVE-1 EXHAUST SAMPLE ANALYSIS RESULTS OSHA

Accm
750

Acetone

0.67
ND

0.18
ND

0.29

ND

750

M-DichJoroethylene Methyl Ethyl Ketone (MEK) TettachloroethyleM Trichloroethylene (TCE)

082
OJ3

ND
038 300

232
ND

200

ND

ND
OJ6

OJB
(US

107

an

50

SO

ND · AnaJyte wi» not detected it concentrations petter than or equal to the quantitatioa limit 1 Occupational Safety and Health Adminiitntion (OSHA) 29 CFR 1910.1000 permictible ei^ocure limit, 8-hour time-weighted average. * American Conference of Governmental Industrial Hypetiitt (ACGDi) threshold limit value, 8-hour time-weighted avenge, ppm = parts per

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 Acetone Methyl Ethyl Ketone Trichloroethylene Average Destruction Efficiency 99.8% 98.4% 99.3%

In the report entitled SVE Pilot Testing Final Report, dated February 1993, Unidynamics recommended use of the thermal oxidation technology 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 BSD 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

The analysis of certain exhaust samples taken during conditions 1 and 4, when the SVE-1 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

8

Administrative Record Document No. 29

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1991 BSD requirements specifying soil target areas and soil cleanup standards remain unchanged. B. Subunit A Groundwater Treatment Remedy The ROD states that the Subunit A Groundwater Treatment Remedy for the PGA site-north consists of pump and treat technology using both air stripping and liquid-phase GAG with vapor-phase GAC This remedy is scheduled to be

treatment of the air emissions. implemented in three phases. solely on Unidynamics

Phase 1 facilities will be located and consist of extraction,

property

treatment, and reinjection of Subunit A groundwater contamination plus some limited contribution from Subunit B. facilities will pump and treat only Subunit Phases 2 and 3 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 liquidphase 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 9OO
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ppb. ppb.

The MEK clean-up level established by the 1991 BSD is 350 During 1991 and 1992, EPA directed Unidynamics to implement

a special groundwater sampling program to confirm the extent and approximate amount of MEK groundwater contamination. In accordance with the document entitled Special Sampling Event10 dated February 10, 1992, Unidynamics implemented a focused groundwater testing of the two wells that indicated prior MEK 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 Unidynamics1 groundwater samples. The data results of the Special Sampling

Event are documented in a Unidynamics' letter report dated March 3, 1992 and an ADEQ letter report11. Unidynamics and ADEQ samples Data results from both the indicated non-detectable

concentrations of both MEK and acetone. In April 1992, EPA approved Unidynamics1 plan to continue searching for ketone groundwater contamination in the targeted three wells as part of Unidynamics1 on-going quarterly well program. No significant ketone groundwater

monitoring

contamination has been detected to date. Therefore, in the absence of ketone groundwater contamination, this ESD suspends immediate implementation of the liquid-phase GAG unit and requires air

stripping alone as the sole Subunit A groundwater remedy treatment
10 11

Administrative Record Document No. 8

See Administrative Record Document No. 10 for Unidynamics letter and Administrative Record Document No. 9 for ADEQ letter.
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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-volatile compound, such as methyl ethyl ketone or acetone, be drawn into the Subunit A groundwater remedy in concentrations clean-up at or in excess design of of a 50% of a site

groundwater

standard,

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 Requirements The ROD specifies that treated Subunit C groundwater generated by the Subunit C Groundwater Remedy at the northern portion of the
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PGA site shall be incorporated into the community potable water supply. This BSD 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 Subunit 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 extraction by a City for municipal use via EPA has

of Goodyear municipal well.

determined that reinjection of the treated water at or below the standards established by Table 2-5 of the ROD (as modified by the 1991 BSD and this BSD) 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 reinjection or a municipal end-use (see

alternative may be submitted for EPA review and approval Section III.E for additional explanation). Modifications to the ROD Remedy for PGA Site-south

D. Treatment Technology for the Subunit B/C Groundwater Remedy. 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
20

plant using

the air

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stripping technology (without air emission controls) shall be used to treat water from three new extraction wells. This BSD changes

the treatment technology for the Subunit B/C groundwater remedy from a centralized air stripping system to two or more independent liquid-phase GAG treatment systems. EPA is making this change to

the ROD due to a reduction in the estimated extraction flow rate for the Subunit B/C groundwater remedy and pipeline access

difficulties encountered when trying to design 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 groundwater contamination emanating from the airport property was substantial and had migrated all the way to the Phillips wells located about 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. eight old

The work consisted of: (a) investigating and addressing 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 Loral and airport properties. The results of this investigation are detailed in the report entitled Conceptual (30%) Design Report for the Ground-Water Remedy at the Phoenix-Goodvear Airport Superfund Site in Goodyear.

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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. volume of Subunit B/C contamination This reduction in the

has caused the estimated

extraction flow rate to decrease from 2200 gallons per minute (gpm) to about 700 gpm. The significantly reduced extraction rate

allowed liquid-phase GAC to become a viable treatment alternative. In addition, early in the design 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 rcsduces 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 BSD 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
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environment, the liquid-phase GAC systems required by this BSD 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 Requirements 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. changes the ultimate disposition of the treated This BSD

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. explained further below, if after 1994 EPA determines As 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 EPA designated the City of

subject to operational difficulties.

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

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described

in paragraph

D.

above, the

extent

of

Subunit

B/C

groundwater contamination was decreased, thereby decreasing the extraction flow rate of water to be remediated from about 2200 gpm to about 700 gpm. 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 TDS to acceptable levels at a 2200 gpm 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 costeffectiveness of the reinjection alternative by reducing the number of reinjection 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 BSD 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 Design Report for the Subunit B/C Ground-Water Remedy at the Phoenix-Goodvear Airport Superfund Site in Goodyear.

13

Administrative Record Document No. 5
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Arizona and scheduled for construction during 1993 and 1994, the required end-use requirement for treated Subunit B/C groundwater shall be reinjection aquifer. maintenance If after back into the Subunit B/C portion of the 1994, EPA determines that operation and

of Subunit B/C groundwater

reinjection

wells for

Subunit B/C groundwater remedial actions are not a cost-effective end-use alternative, plans and specifications for a modified

reinjection system or for conversion to a municipal 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 B/C groundwater remedial actions that are not constructed during 1993-94 pursuant to the Goodyear Tire and Rubber Company document entitled Final Design Report for the Subunit B/C Ground-Water Remedy at the Phoenix-Goodyear Airport Superfund Site in Goodyear. Arizona, this BSD 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 B/C 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 BSD and this BSD) . It must be noted here that any end use
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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 BSD is consistent with state law and not subject to a state permit. However, any

attempts to design and implement a municipal end use alternative shall be subject to state and local law including permitting

requirements, if any. Site-wide Modifications F. Drinking Water Well Protection. This BSD adds the following

requirement to the ROD: In the event that any private or municipal drinking water well, including, but not limited to, City 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 BSD) 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 well(s) shall be treated by wellhead liquid-phase GAG 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 The immediacy

concentration at its groundwater cleanup standard.

of such proper design, procurement, and construction activities shall be based on EPA assessment of trends in drinking water well
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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 BSD14. These data indicate that, with some exceptions to

date, no City of 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 sampled15. in nature. These exceptions were each minor

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 15

Administrative Record Document No. 31

For the last five years, TCE concentrations in City of Goodyear drinking water wells and the Parkshadows drinking water well 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) Well 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.
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clear directive for protection of public health in the case of this unlikely event, EPA has decided to add the wellhead treatment requirement as described above. It must be rioted that this

drinking water wellhead treatment requirement may not be determined by EPA to be an adequate long-term response action for groundwater 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-up Levels for Benzene. Ethylbenzene. 1,1.2,2 Tetrachloroethane. and Tetrachloroethene. Table 2-5 of the ROD The

provides the groundwater clean-up standards for the PGA site.

1991 BSD revised the MEK groundwater clean-up standard to be 350 ppb and adopted 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 BSD. These four new contaminants and are benzene, ethylbenzene, (also 1,1,2,2known as

tetrachloroethane,

tetrachloroethene

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
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contaminants

shall

be

determined

based

upon

a

decision-tree

described in the ROD and are related to their clean-up levels in groundwater. It must be noted here that consistent with the "petroleum exclusion11 allowed by CERCLA, the groundwater cleanup standards for benzene and ethylbenzene are not applicable to actions related to the clean up of petroleum underground 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 5 ppb18 1,1,2,2-tetrachloroethane: 0.18 micrograms per liter or 0.18 ppb19 The above groundwater clean-up standards for benzene, products released from a petroleum

tetrachloroethene, 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. same as 13.

18 19

Reference: Human Health-based Guidance Levels for the Ingestion of Contaminants in Drinking Water and Soil Arizona Department of Environmental Quality, June 1992. (see Administrative Record Document No. 16).
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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 clean-up level listed in Table l 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 Drinking 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) cleanup 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

BSD.
IV. SUPPORT AGENCY COMMENTS The Arizona Department of 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:
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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 If there are any future changes in end

water at Superfund sites.

use, the new end uses(s) roust be consistent with state laws. 2) Pursuant 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 Quality

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 BSD to be an adequate document and submitted the following four comments: 1) ADEQ still recommends that EPA include a reference in the BSD 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 will be conducted on the efficiency of the groundwater air stripping system, since liquid-phase granular activated carbon (GAG) may not be required.
31

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3) Conditions 1-4 of Table 2 on page 15 of the BSD should be explained in the text of the ESD. 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 ESD should state that "ppm" is an abbreviation for "parts per million" (also applicable to Table 1). Comments numbers one and two from ADWR have been incorporated into this ESD. 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

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an BSD 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 BSD dated March 1993. In accordance with Section 117 (c) EPA published in the West

of CERCLA, 42 U.S.C. Section 9617(c),

Valley View newspaper and the Arizona Republic newspaper a notice that describes the proposed BSD 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 BSD and announces its availability for review. In accordance with 40 C.F.R. Section

300.435(c) (2) (ii) , this final BSD 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 BSD.

John tyzse

Acting Regional Administrator

Date

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ATTACHMENT #1

Approximate Boundaries of Phoenix Goodyear Airport Area Superfund Site
Camelback Road

Indian School

Thomas Road

McDowell

Van Buren UNIDVNAMICS F HOENIX, It

Phoenix Goodyear Airport Lower Buckeye Road

Broadway

Glla River

Approximate Site Boundaries
Case 2:03-cv-02226-ROS Document 82-2 Filed 06/27/2006 Page 34 of 41

ATTACHMENT #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 Original 1989 ROD Site Clean-up Plan Airport Area - Soils; Soil vapor extraction with vapor-phase carbon emission controls. - Deep Groundwater; Pump and treat at a centralized air stripping plant. Provide treated water to City of Goodyear. - Shallow Groundwater; Incorporatated 1987 Record of Decision requirement for pump and treat at a centralized air stripping plant with vapor-phase carbon emission controls. Reinject treated water. Unidvnamics Area - Soils; Soil vapor extraction with vapor-phase carbon emission controls. - Deep Groundwater; Pump and treat at a centralized air stripping/liquid-phase carbon treatment plant with vaporphase carbon emission controls. Provide treated water to City of Goodyear. - Shallow Groundwater; Pump and treat at a centralized air stripping/ liquid-phase carbon treatment plant with vaporphase carbon emission controls. Reinject treated water. Additional Site-wide Requirements - none. Additional Site-Wide Requirements - Liquid-phase carbon treatment at the well-head for drinking water wells contaminated by Airport or Unidynamics areas. - Add 4 new groundwater standards. The Site Clean-up Plan as modified by ESD#2 Airport Area - Soils; same as 1989 ROD.

- 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.

Unidynamics Area " Soils; 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.

- Shallow Groundwater; same as the 1989 ROD except suspend implementation of the liquid-phase carbon unit until warranted.

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ATTACHMENT #3 A summary of the legally applicable state and federal requirements and other criteria for groundwater clean-up levels as reported in Table 2-5 of the September 1989 Record of Decision for PhoenixGoody ear Airport Area Superfund Site including modifications established by the January 1991 Explanation of Significant Differences (1991 BSD) and modifications established by ESD#2.

All Concentrations are in micrograms per liter. Compound
1,1-Dichloroethylene

Cleanup Level
7

1,2-Dichloropropane
Chloroform Toluene Trichloroethylene Trichlorofluoromethane

1
100 340 5 1

Carbon Tetrachloride
Methylene Chloride Methyl Ethyl Ketone * Xylenes Antimony Arsenic Barium Beryllium Cadmium Chromium Lead Mercury Nickel Selenium Silver Zinc Acetone ** Benzene ***

5
1 350 440 1.46 50 1,000 0.0039 10 50 50 2 15.4 10 50 5,000 700 5

Ethylbenzene ***
Tetrachloroethene ***

700
5

1,1,2,2-tetrachloroethane ***

0.18

* Revised groundwater cleanup level established by the 1991 BSD ** New groundwater cleanup level established by the 1991 BSD *** New groundwater cleanup levels established by ESD#2

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a a. / "7 - o on
Attachment #4
Page 1 05/06/93 PHOENIX-GOOOYEAR AIRPORT AREA

Superfund Removal Site
EXPLANATION OF SIGNIFICANT DIFFERENCES ADMINISTRATIVE RECORD INDEX
MAY 1993

DATE yy/mm/dd

AR #

AUTHOR

ADDRESSEE

SUBJECT

00/00/00 AR 1

M Chapman, D Field Scotts Graphics, Inc A Naujokas Eastman Kodak Co A Naujokas Eastman Kodak Co Joseph Tessitore, et al Cross/Tessitore & Associates Stephen Cleveland City of Goodyear, AZ

Article: Lessons fr carbon bed adsorption losses Article: Preventing carbon bed combustion problems Article: Spontaneous combustion of carbon bed (Plant/Operations Progress, 4/85: 120-126) Article: Thermal destruction of organic air toxics (Pollution Engineering, 3/90: 58-68) Craig Cooper City of Goodyear proposal for end use Environmental Protection water & irrigation alternatives, Agency - Region 9 w/appendix, oversized map, & TL fr S Cleveland to C Cooper (doc date fr TL) Craig Cooper TL: Transmits technical articles Environmental Protection referenced in Evaluation of Alternatives Agency - Region 9 for Treatment of Extracted Soil Vapor during SVE Testing

00/00/00 AR 2

85/04/00 AR 3

90/03/00 AR 4

90/04/16 AR 5

92/02/07 AR 6

Daniel Herbert Malcolm Pirnie, Inc

92/02/07 AR 7

Craig Cooper William Donahue Ltr: Comments on 10/91 quarterly Environmental Protection Unidynamics Phoenix, Inc groundwater sampling rpt Agency - Region 9 Daniel Hebert Malcolm Pirnie, Inc William Donahue Ltr: Transmits description of work Unidynamics Phoenix, Inc prepared for special sampling event 2/12/92 w/encl

92/02/11 AR 8

92/02/13 AR 9

Moses Olade Craig Cooper Ltr: Transmits analytical results of AZ Dept of Environmental Environmental Protection groundwater samples fr Unidynamics Quality Agency - Region 9 special sampling event 2/92 w/encl &
w/TL fr K DeWhitt to W Turner 3/3/92

92/03/03 AR 10

Daniel Hebert Malcolm Pirnie, Inc

William Donahue Ltr: Reports results of special Unidynamics Phoenix, Inc groundwater sampling event conducted 2/12/91

92/03/09 AR 11

Craig Cooper William Donahue Ltr: Approves special sampling event Environmental Protection Unidynamics Phoenix, Inc for MW-4, HVl-7 & MW-8 wells Agency - Region 9 Malcolm Pirnie, Inc Evaluation of alternatives for treatment

92/03/13 AR 12

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Page 2 05/06/93 PHOENIX-GOODYEAR AIRPORT AREA Superfund Removal Site EXPLANATION OF SIGNIFICANT DIFFERENCES ADMINISTRATIVE RECORD INDEX MAY 1993

DATE yy/mm/dd

AR #

AUTHOR

ADDRESSEE

SUBJECT

of extracted soil vapor during SVE (soil vapor extraction) pilot testing 92/04/07 AR 13 Craig Cooper William Donahue Ltr: Soil vapor extraction (SVE) pilot Environmental Protection Unidynamics Phoenix, Inc testing (US Amended Admin Order Docket Agency - Region 9 #90-20) Craig Cooper WiIIiam Donahue Ltr: Soil vapor extraction (SVE) pilot Environmental Protection Unidynamics Phoenix, Inc testing Agency - Region 9 Craig Cooper Ltr: Proposed revision to test methods Bill Donahue Unidynamics Phoenix, Inc Environmental Protection Agency - Region 9 AZ Dept of Environmental Quality Human health-based guidance levels for ingestion of contaminants in drinking water & soiI Health & safety plan: Soil vapor extraction (SVE) remedial design & operation activities (revised 7/31/91) w/TL fr D Hebert to C Cooper 7/30/92

92/04/07 AR 14

92/04/20 AR 15

92/06/00 AR 16

92/07/00 AR 17

Malcolm Pirnie, Inc

92/07/08 AR 18

Wi11iam Donahue Craig Cooper Monthly rpts for remedial activities for Unidynamics Phoenix, Inc Environmental Protection 5/92-7/92, dated 6/9/92 & 7/8/92 (Admin Agency - Region 9 Order Docket #90-20) Craig Cooper Environmental Protection Agency - Region 9 Malcolm Pirnie, Inc William Donahue Ltr: Follow-up issues to 6/25/92 mtg Unidynamics Phoenix, Inc including VLEACH rpt, SVE pilot program, & gw remedy Soil vapor extraction (SVE) pilot testing program description & interim routine sampling program at Unidynamics w/TL fr W Donahue to C Cooper 8/31/92

92/07/21 AR 19

92/08/00 AR 20

92/08/11 AR 21

Craig Cooper William Donahue Ltr: Soil vapor extraction (SVE) pilot Environmental Protection Unidynamics Phoenix, Inc testing program Agency - Region 9 Daniel Hebert Malcolm Pirnie, Inc William Donahue Ltr: Transmits results fr re-sampling & Unidynamics Phoenix, Inc analysis of MU-4, MU-7 & MW-8 wells w/encls & Itr fr J Harlan to C Gordon 8/19/92

92/08/25 AR 22

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Page 3 05/06/93
PHOENIX-GOODYEAR AIRPORT AREA

Super-fund Removal Site
EXPLANATION OF SIGNIFICANT DIFFERENCES ADMINISTRATIVE RECORD INDEX MAY 1993

DATE yy/wn/dd

AR #

AUTHOR

ADDRESSEE

SUBJECT

92/08/28 AR 23

Craig Cooper William Donahue Ltr: Soil vapor extraction (SVE) pilot Environmental Protection Unidynamics Phoenix, Inc testing prog (US Amended Admin Order Agency - Region 9 Docket #90-20) Malcolm Pirnie, Inc Environmental Protection Agency - Region 9 Final groundwater sampling rpt

92/10/00 AR 24

92/11/03 AR 25

Craig Cooper Ltr: Transmits sampling & analysis of Byron James AZ Dept of Environmental Environmental Protection irrigation & drinking water supply wells at Park Shadows Apartments, Goodyear, AZ Quality Agency - Region 9 w/encls Daniel Hebert Malcolm Pirnie, Inc Ltr: Transmits copy of revised soil Craig Cooper Environmental Protection vapor extraction (SVE) pilot testing program description w/encl Agency - Region 9 Ltr: Transmits revised conceptual (30%) Craig Cooper Environmental Protection design rpt for groundwater remedy, 2 oversize maps, & Goodyear comments on Agency - Region 9 design rpt w/encls

92/11/10 AR 26

92/11/16 AR 27

Todd Struttman Sharp & Assoc

92/11/24 AR 28

Ltr: Revised Soil vapor extraction (SVE) William Donahue Craig Cooper Environmental Protection Unidynamics Phoenix, Inc pilot testing program Agency - Region 9 Malcolm Pirnie, Inc Unidynamics Phoenix, Inc Soil vapor extraction (SVE) pilot testing rpt Selected guidance documents, Explanation of Significant: Differences (ESD), 3/92 Ltr: Transmits analytical data for City Craig Cooper Environmental Protection of Goodyear municipal wells & for Park Shadows Apartments wells w/encl (Cont Agency - Region 9 #68-W9-5400, WA #54-12-9P19) Ltr: Reviews groundwater remedy phase 1 Craig Cooper Environmental Protection design analysis & need for granular activated carbon polishing (GAC) (Cont Agency '- Region 9 #68-W9-0054, WA #54-12-9P19) Public notice of availability of proposed Explanation of Significant Differences (ESD) for cleanup of PGA Superfund Site

93/02/00 AR 29

93/02/02 AR 30

Environmental Protection Agency - Region 9 Lawrence Smith URS Consultants, Inc

93/02/17 AR 31

93/02/18 AR 32

Lawrence Smith URS Consultants, Inc

93/03/00 AR 33

Environmental Protection Agency - Region 9

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Page 4 05/06/93
PHOENIX-GOODYEAR AIRPORT AREA

Superfund Removal Site
EXPLANATION OF SIGNIFICANT DIFFERENCES ADMINISTRATIVE RECORD INDEX MAY 1993

DATE yy/mm/dd

AR #

AUTHOR

ADDRESSEE

SUBJECT

93/03/00 AR 34

Craig Cooper Environmental Protection Agency - Region 9

Proposed Explanation of Significant Differences #2 for the Final Remedy Record of Decision

No. of Records: 34 \arfinal1.rpt

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Page 1 05/06/93
PHOENIX-GOODYEAR AIRPORT AREA

Superfund Removal Site
EXPLANATION OF SIGNIFICANT DIFFERENCES ADMINISTRATIVE RECORD INDEX SUPPLEMENT 1, MAY 1993

DATE yy/mm/dd

AR #

AUTHOR

ADDRESSEE

SUBJECT

93/03/10 AR 35

Environmental Protection Agency - Region 9 Mason Bolitho AZ Dept of Water Resources

Public mtg re 3/93 Explanation of Significant Differences (ESD) (transcript) Craig Cooper Ltr: Comments on Explanation of Environmental Protection Significant Differences (ESD) Agency - Region 9

93/03/16 AR 36

93/03/19 AR 37

Bryon James Craig Cooper Ltr: Transmits comments on Explanation AZ Dept of Environmental Environmental Protection of Significant Differences (ESD) w/encl Quality Agency - Region 9 Stephen Cleveland City of Goodyear, AZ Craig Cooper Environmental Protection Agency - Region 9 Environmental Protection Agency - Region 9 Craig Cooper Ltr: Comments on Explanation of Environmental Protection Significant Differences (ESD) Agency - Region 9 Explanation of Significant Differences #2 (ESD #2) for final remedy Record of Decision Public notice of availability of Explanation of Significant Differences (ESD) for cleanup