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Pacific Southwest, Region 9: Superfund

Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations

South Indian Bend Wash Area

EPA #: AZD980695969

State: Arizona(AZ)

County: Maricopa

City: Tempe

Congressional District: 00

Other Names:

Bulletin Board

The Second Five-Year Review Report was completed in September 2016 and can be viewed by clicking here.


NEWS FEATURE ! (press release dated 12/4/06)

Description and History

NPL Listing History

NPL Status:

Proposed Date: 12/30/82

Final Date: 09/08/83

Deleted Date:

The entire area of the Indian Bend Wash Superfund Site (IBW Site) covers approximately 13 square miles in Scottsdale and Tempe, Arizona. EPA divided the Site into two areas known as North Indian Bend Wash (NIBW) and South Indian Bend Wash (SIBW). NIBW and SIBW are on separate cleanup tracks. Groundwater within the SIBW site has nearly achieved drinking water standards already.

This Site Overview focuses on SIBW only. More information on NIBW can be found at: NIBW.

EPA and ADEQ have been involved in investigations and cleanup activities at NIBW and SIBW since the initial discovery of VOCs in the groundwater in 1981. The entire Site, including both NIBW and SIBW, was placed on EPA's National Priorities List (NPL), or Superfund list, in 1983.

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Contaminants and Risks

Contaminated Media
  • Groundwater
  • Soil and Sludges

Groundwater and soils (in certain isolated areas) were contaminated with VOCs, including TCE and PCE. Groundwater is nearly cleaned up and is being monitored for long term control.

The primary risk at SIBW was to individuals who may have consumed contaminated groundwater before it was discovered in 1981. Since individuals are currently not drinking the contaminated groundwater, there is no direct human health threat associated with the groundwater contamination. All drinking water in the Tempe area is provided by municipal drinking water suppliers. This water can not be served to customers unless it meets all drinking water standards set by the federal Safe Drinking Water Act.

Wells can not be drilled in the state of Arizona without a permit from the Arizona Department of Water Resources (ADWR). EPA works with ADWR to coordinate the cleanup efforts at SIBW. If someone applied for a well permit, ADWR would inform them of the risks of using the groundwater for drinking, showering, etc.

The original concern associated with contaminated soils was the potential to impact groundwater. If individuals were to come into direct contact with contaminated soil, due to the low concentrations of contaminants present in surface and deep soil, the potential health risks would be minimal or insignificant.

As a result of the 2016 Second 5 Year Review recommendations, EPA has begun a reassessment of potential for chemical vapors remaining in shallow soils in former industrial areas to migrate in residential and commercial buildings. In April 2017, EPA mobilized its Trace Atmospheric Gas Analyzer (TAGA) bus, a mobile laboratory to evaluate potential vapor intrusion risk at the NIBW and SIBW sites. Data from the April 2017 did not identify a vapor intrusion problem at the site. However, EPA will continue to collect data during the winter months for confirmation.

If you have questions about TCE, please review the Agency for Toxic Substances and Disease Registry's (ATSDR's) TCE fact sheet at http://www.atsdr.cdc.gov/toxfaqs/TF.asp?id=172&tid=30 and EPA'sTechnical Factsheet on: TRICHLOROETHYLENE (TCE) under the Documents and Reports section below.

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Who is Involved

This site is being addressed through Federal and potentially responsible parties' actions.

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Investigation and Cleanup Activities

This site is being addressed in two long-term remedial phases. For the most part, the work has been divided into the following management units: (1) soil; and (2) groundwater. The EPA is addressing SIBW as a separate area of study from NIBW because the contaminants come from different sources and the groundwater plumes are not contiguous.

Site Studies

The Remedial Investigation (RI) for SIBW was conducted over a period of many years and characterized both soil and groundwater conditions. Interim RI Reports were completed in 1991 and 1993. The final RI and the Groundwater Feasibility Study (Groundwater FS) were completed in 1997.

Remedy Selected

On September 27, 1993, EPA issued a Record of Decision for the Soil Operable Unit entitled, “VOCs in the Vadose Zone” (1993 Soils ROD). This ROD selected Soil Vapor Extraction (SVE) as the cleanup technology for VOCs in soils at SIBW.

Within the SIBW study area there are many facilities at separate locations which are known as subsites. These subsites have the same VOC contamination and very similar types of soils. Traditionally, EPA would investigate and then evaluate cleanup alternatives for each facility or subsite. However, due to the similarities among the SIBW subsites it was likely that the same cleanup would have been selected in each case. Rather than select the same remedy repeatedly for many facilities, EPA selected a remedy in the 1993 Soils ROD that utilized the “Plug-in Approach” in order to save time and resources.

Using this approach, EPA selected a cleanup technology (SVE) that would apply whenever a certain set of conditions existed. This set of conditions was defined in the 1993 Soils ROD. First, investigations ( “Focused Remedial Investigations” or FRIs) were required to be conducted at each subsite. EPA compares the data results with the standard criteria, and If the facility meets the specified conditions, then soil cleanup is required at that facility.

Once EPA has made a decision regarding whether or not a particular subsite meets the criteria, EPA then issues a “Plug-in Determination Document” and makes the FRI Report available for the public to review. To date, EPA has issued two Plug-in Determinations. The first was in February 1994 for the DCE Circuits Subsite. Soil cleanup was required at DCE Circuits and this cleanup is currently nearing completion. The second Plug-in Determination was issued in January 2002 for the following seven subsites: Circuit Express, Allstate Mine Supply, Desert Sportswear, Cerprobe, Service and Sales, and the City of Tempe Right-of-Way. None of these seven subsites plugged-in to the 1993 Soils ROD and, therefore, soil cleanup was not required.

On September 30, 1998, EPA issued a Record of Decision for VOCs in groundwater (1998 Groundwater ROD). The 1998 Groundwater ROD addressed all three groundwater plumes at the SIBW Site: the western plume, the central plume and the eastern plume. The remedy selected for the western plume was extraction and treatment and the remedy selected for the central and eastern plumes was monitored natural attenuation (MNA). In 2013 EPA implemented a pilot test of Insitu Chemical Oxidation (ISCO) by injecting permanganate into 5 wells within the eastern groundwater plume. These wells were not predicted to meet drinking water criteria for 30 years. Subsequent monitoring has demonstrated attainment of drinking water standards has been nearly met as of 2017.

Cleanup Ongoing

EPA became the lead for site cleanup in the 2000's. The MNA remedy effectively cleaned up the central, western, and eastern plumes. EPA is currently monitoring to gauge long term remedy success.

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Cleanup Results to Date

After adding this Site to the NPL, EPA performed preliminary investigations and determined that no immediate actions were required at the Site. Remedies have been selected and cleanup activities in various stages are nearly completed, and confirmation monitoring is ongoing.

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Potentially Responsible Parties

Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.

Online information about the PRPs for the site is not available.

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Community Involvement

Public Meetings: General public meetings have been held since the early 1990s. These have included a meeting on the Proposed Plan for Cleanup in September 1997 and one on a Revision to a portion of the cleanup stategy in March 2004.

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Public Information Repositories

The public information repositories for the site are at the following locations:

Tempe Public Library
3500 South Rural Road
Tempe, AZ 85282

Arizona Department of Environmental Quality
1110 West Washington Street
Phoenix, AZ 85007

The most complete collection of documents is the official EPA site file, maintained at the following location:

Superfund Records Center

Mail Stop SFD-7C

95 Hawthorne Street, Room 403

San Francisco, CA 94105

(415) 820-4700

Enter main lobby of 75 Hawthorne street, go to 4th floor of South Wing Annex.

Additional Links

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EPA Site Manager
Carolyn dAlmeida
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Carlin Hafiz
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
State Contact
Laura Fischer
Arizona Department of Environmental Quality
1110 West Washington Street
Phoenix, AZ 85007
PRP Contact
Community Contact
Other Contacts
After Hours (Emergency Response)
(800) 424-8802

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