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Pacific Southwest, Region 9: Superfund

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

Tuba City Open Dump

EPA #: NND982400145

State: Arizona(AZ)

County: Coconino

City: Tuba City

Congressional District: 03

Other Names:

Bulletin Board

The Community Involvement Plan for the Tuba City Open Dump is now available.

Tuba City CIP 2_13.pdfTuba City CIP 2_13.pdf


Description and History

NPL Listing History

NPL Status: Not on the NPL

Proposed Date:

Final Date:

Deleted Date:

The Tuba City Open Dump (TCOD) is located near Tuba City, Arizona. It is adjacent to US Highway 160, approximately one mile east of State Highway 264 junction. The site is on land under two tribal jurisdictions and consists of approximately 30 acres (28 acres on the Hopi Reservation and two acres on the Navajo Nation).

Since the 1940s, the site was a dumping area where local businesses, schools, agencies, and the public dumped waste. During this time, it was not regulated nor supervised as a solid waste disposal site. The landfill received waste from the Tuba City area and, to a lesser extent, from the Moenkopi area. In addition, waste from other areas may have been disposed of at the TCOD due to its unrestricted access and location along a major highway. The Bureau of Indian Affairs (BIA) periodically provided limited maintenance to the site by constructing and back filling trenches at the dump site.

Since the TCOD was unmanned and unsecured during its operation, information about the disposed wastes is limited. The BIA closed the TCOD to additional waste disposal in 1997; however, the TCOD does not meet Federal and Tribal regulatory requirements for permanent closure.

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Contaminants and Risks

Contaminated Media
  • Groundwater
  • Soil and Sludges

Contaminants in solid waste material and soil

Solid waste in the TCOD includes municipal waste, medical waste, and metal debris. To date, studies show that most waste in the TCOD is municipal solid waste. However, arsenic, copper, strontium, and vanadium have been identified at elevated concentrations in soil compared to native soil and rock. Uranium-contaminated waste, equipment, or tailings may have been disposed of at the dump. However, no radioactive waste materials have been found in the TCOD.

Contaminants in groundwater

After of the BIA began environmental monitoring in 1995, radioactive contamination (including uranium and gross alpha and beta activity) was discovered in the shallow groundwater at levels exceeding the U.S EPA drinking water standards, known as Maximum Contaminant Levels (“MCLs”). MCLs are the maximum concentrations at which the contaminants are not considered to pose a significant risk to human health and the environment.

The shallow groundwater, very near to the dump, is contaminated with elevated levels of arsenic, chloride, lead, total dissolved solids (TDS), chromium, nitrate, selenium, strontium, sulfate, and vanadium.


Groundwater contamination and potential threats to drinking water

      Supply wells and springs located within 4000 to 7000 feet of the Site provide drinking water and irrigation to the Village of Moencopi (Lower) and Upper Village of Moenkopi. Recent testing of these supply wells and springs indicates that they are not contaminated. However, contaminants have been detected above EPA MCLs in monitoring wells within 2,600 feet of the supply wells and springs.

      BIA has implemented a groundwater monitoring program that is conducted by the Hopi Tribe to regularly collect and analyze groundwater samples in the monitoring wells across the site.

Is it safe to drink water supplied to the public?

      The Navajo Tribal Utility Authority is providing clean water to Navajo residents. Hopi residents of the Upper Village of Moenkopi get their drinking water from three public supply wells. These supply wells are tested regularly by the Hopi Tribe to ensure they meet Federal and Tribal drinking water standards. The public drinking water is safe to drink and is not affected by the TCOD. The Village of Moencopi (Lower) obtains its drinking water from two springs, one of which feeds a small community water system with four outdoor taps in the village. The spring water is safe to drink.

      The BIA is completing a Remedial Investigation and Feasibility Study to evaluate whether contaminants from the TCOD pose a future risk to the drinking water.

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Who is Involved

The United States Environmental Protection Agency (U.S. EPA) and the BIA are working with the Hopi Tribe and Navajo Nation to investigate and address the contamination. Other federal agencies involved in the investigation and closure of the site include: - U.S. Geological Survey (USGS)
- Indian Health Service (IHS)
- Department of Energy (DOE)

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Investigation and Cleanup Activities

Over the past several years, a number of site assessment activities have been conducted to understand the environmental conditions at the TCOD. No cleanup actions have been conducted at this site.
Tuba City Open Dump - Current and Future Projects

1. Interim Action Report - completed June 6, 2009

The BIA published the Interim Action Report on June 6, 2009. The report provided an evaluation of the current conditions of the site and listed a number of recommendations for interim actions to address the immediate risks associated with the TCOD. The following interim actions were identified for implementation to reduce or control the impact(s) to human health and the environment:

Continuation of groundwater monitoring

    Quarterly groundwater monitoring is a key component to monitoring and evaluating seasonal and long trends in the distribution of the various contaminants in the shallow groundwater. This information is very useful in planning and guiding future investigation and closure actions for the TCOD. As a result, BIA has recommended that this activity be continued.

    Focused source investigation and removal of waste around Monitoring Well 07 (MW07)

    Investigations in the MW07 area of the TCOD have detected the presence of radionuclides in the shallow groundwater at much higher levels than other areas within the site. The BIA entered into an Interagency Agreement (IA) with EPA that provided $1.2M to EPA to conduct a source investigation in the vicinity of MW07. This investigation will characterize the waste in this area and properly dispose of the investigation-derived waste from this activity (see #2 below for details about the Source Characterization Project).

    Drinking water well head protection study
    The shallow groundwater at the site has been impaired by a number of sources. The municipal water supply wells in this area are screened across both shallow and deep groundwater intervals, which could allow the impaired shallow groundwater to enter the wells. Currently, the water quality in the supply wells meets drinking waters standards for both tribal and federal standards. However, the BIA has recommended and funded a protective measures study to ensure that the supply wells continue to produce clean water for the community.

    Fencing of the old cell
    The BIA has recommended that the old dump cell be fenced to limit access. The hazardous items on the ground of the old cell could potentially harm humans and livestock/animals that come in contact with the items. This work has been completed.

The above recommendations are designed to reduce immediate risk at the TCOD while the long-term closure plan is being developed.

2. Source Characterization Project - Fall and Winter 2009

During fall 2009, EPA implemented a uranium source characterization project. The goal of the investigation was to locate uranium hotspots within the vicinity of MW-07, which may be contributing to elevated concentrations of uranium in groundwater. The project tasks included the following:

    1) Characterize the waste material and locate source(s) of uranium contamination in the vicinity of MW-07;
    2) Remove and dispose of Investigation-Derived Waste (IDW);
    3) Install two additional monitoring wells and collect groundwater quality and flow information; and
    4) Evaluate possible shallow groundwater containment options.

The source characterization work was carried out in phases.

Phase I: Comprehensive document review and development of sampling and field work plans.

Phase II: Field work.

The first phase of field work entailed surface surveying (e.g. magnetometer survey, electrical resistivity survey, and in-situ gamma survey). After the surface surveying, EPA drilled waste borings and dug test pits to visually and chemically analyze the contents of the landfill in the vicinity of MW-07. EPA collected chemical and radiation measurements and conducted soil and waste profiling of the unearthed material. The EPA planned to remove waste that may be contributing to the elevated uranium concentrations in groundwater and to dispose all waste materials, including materials containing radiological contamination, pursuant to a radiological materials and IDW disposal work plan. All clean soil was returned to the excavated area.

The last phase of the field work was the installation of two groundwater monitoring wells and collection of groundwater quality and flow data. This information was to be used in a preliminary evaluation of groundwater containment options.

During the field work EPA implemented dust suppression measures to reduce the amount of fugitive dust from the project site. EPA restored the disturbed area by grading, filling and re-vegetating.

The results of this work were presented in "Data Summary Report: Monitoring Well 7 Investigation Area (9/17/10)."

3. Remedial Investigation and Feasibility Study - Ongoing, Completion Estimated in 2014.

In addition to studying immediate health risks and taking interim actions to address these risks, BIA is collecting information to develop long-term solutions for closing the Site. This investigation and the resulting reports are called a Remedial Investigation and Feasibility Study (RI/FS), which is under the Comprehensive Environmental Response, Compensation and Liability Act (Code of Federal Regulations Title 40 Part 300). BIA has developed a RI/FS workplan.

The RI/FS will incorporate and build on past studies conducted by the BIA, the Hopi Tribe and the Navajo Nation. The RI/FS will involve the collection and compilation of groundwater, surface soils, subsurface soils, and waste data from the site. The goal for the RI/FS is to help select a remedy that eliminates or sufficiently reduces or controls risks to human health and the environment. The BIA initated the RI/FS work in June 2011.

Based on the RI/FS and comments received from the public, a final remedy will be selected for closure of the TCOD. This decision will be documented in a Record of Decision (ROD).

Initial Actions

Site Studies

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Cleanup Results to Date

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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.

The BIA is currently taking the lead as PRP for ongoing work at the site.

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Community Involvement

Public Meetings: In September 2008, EPA held two public meetings, one for the Hopi Tribe and one for the Navajo Nation, to update the communities on the closure activities for the TCOD. Both the Hopi Tribe and Navajo Nation were not pleased with the process or the progress of site closure. Both tribes want the BIA to clean close the TCOD immediately instead of more studies and delays.

The EPA conducted community involvement activities throughout the source characterization project. EPA conducted outreach to nearby residents to ensure their needs will be met during the field activities. This outreach was done in advance of field activities. EPA also evaluated the need for relocating nearby residents in the vicinity of the source characterization field work. EPA developed and mailed fact sheets to the community and we held a public meeting to discuss the project with community members during fall 2009.

The EPA will be lead in conducting community involvement activities throughout the RI/FS process.

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Public Information Repositories

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

No public information repositories have yet been established.

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
Jeff Dhont
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Alejandro Diaz
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
State Contact
PRP Contact
Community Contact
Other Contacts
After Hours (Emergency Response)
(800) 424-8802

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