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Nineteenth Avenue Landfill

This site is not a Federal Facility.

Updated: March 27, 2003

NINETEENTH AVENUE LANDFILL
AZIZONA
EPA ID# AZD980496780

EPA Region 9
City: Phoenix
County: Maricopa
Other Names: Salt River Landfills

Site Responsibility:

This site is being addressed through Federal, state and local actions.

NPL LISTING HISTORY

Proposed Date:12/30/1982

Final Date:09/08/1983

Deleted Date:

During the remedial investigation (RI), the groundwater was found to contain very low levels of volatile organic compounds (VOCs), heavy metals including arsenic, barium, mercury, and nickel, and beta radiation. The only compound that is above drinking water standards (MCLs) is 1,1-dichloroethylene (1,1-DCE). Sampling of soil and refuse in the landfill during the RI had shown that the contents of the landfill are generally similar to those expected in municipal landfills, although refuse in the landfill also contains VOCs and pesticides. Soil contained VOCs, polychlorinated biphenyls (PCBs), heavy metals and pesticides. During the RI, the most frequently detected VOCs were ethyl benzene, 1,4-dichlorobenzene, xylenes and toluene.

Potential public health risks could occur if landfill material were washed out of the landfill as the result of flows in the Salt River, although this risk cannot be quantified. Again, with the channelization and stabilization of the Salt River Channel, this scenario is unlikely to occur in the future. The surface water concern is based on the potential for surface water runoff to contact refuse and transport this material to the Salt River, as has occurred in the past during periods of heavy river flow, thereby potentially increasing the risk for a surface water exposure pathway and a sediment exposure pathway. A more likely potential risk to public health and the environment could occur as the result of a rising water table which saturates a greater volume of refuse and releases additional leachate. The risk to the environment resulting from additional leachate generation by this mechanism is unknown and cannot be precisely quantified, although leachate may impact the quality of groundwater and thereby increase the risk for the human groundwater exposure pathway. Although the groundwater table is still in contact with refuse in the landfill during periods of flow in the adjacent Salt River, the existing monitoring network indicates that there is minimal resultant contamination of the groundwater. The Groundwater Contingency Plan for this site, explained in more detail in the next section, ensures continued monitoring of the groundwater in the vicinity of the landfill to evaluate and remediate potential degradation of the groundwater from the landfill. Exposure to groundwater from a shallow drinking water well, assuming such a well were drilled on or near the landfill boundary and used as a drinking water source, represents the only quantifiable potential public health risk.

Immediate Actions: Earthen berms were constructed on the site to limit access. The site was covered with sand, gravel, and stones. In 1981, the City installed a system to collect methane gas and installed monitoring wells to sample the groundwater. There is a fence around the perimeter of the site to prevent unauthorized access.

Entire Site: In 1989, the EPA and ADEQ selected a remedy to clean up the landfill by installing a gas collection and treatment system, covering the landfill with a clay soil cap to prevent water from coming in contact with the buried materials, and constructing bank protection levees between the river and the landfill to prevent erosion. In 1990, the City of Phoenix began designing the technical specifications to clean up the site. Design activities were completed in May 1995.

The City’s construction contractor started work on the bank protection system on August 14, 1995. By the end of August, work had started on the grade control structure and site grading for the capping system. On December 14, 1995, Explanation of Significant Difference (ESD) #1 was signed by ADEQ. ESD #1 changed the perimeter drainage lining material from gunite to Armorflex. Also in December, areas of site grading were completed and work on the capping system was started. By March 1996, the bank protection system and grade control structure were completed, and work on the gas collection system was started. The installation of the Armorflex channel and sedimentation pond lining system was started in May 1996. The site landscaping was started in July 1996. The capping system and site landscaping were both completed by the end of November 1996.

The gas collection system and the two flare stations were completed in October 1996. The emissions testing for the flare stations at Cell A and Cell A-1 were performed on October 16-18, 1996 and were satisfactory. An air permit was subsequently issued to the City. The landfill gas collection system has been operational and functional since February 1997.

Containment of landfill wastes and minimization of infiltration by precipitation or any liquids is achieved by the construction of a compacted clay-soil cap with surface drainage structures to channel precipitation off of the cap. Construction of levees along the landfill cells that border the Salt River will prevent erosion and overtopping from the Salt River. The original earthen channel for storm water drainage along the eastern boundary of the site was replaced by a subsurface pipe with backfill to prevent erosion undercutting along the east boundary of the landfill.

The Preliminary Close-Out Report (PCOR) was completed in February of 1998, documenting construction completion, and the Remedial Action Report was approved in September 1998. The landfill gas treatment system, soil cap, and levee system will continue to be operated and maintained by the City of Phoenix.

1,1-dichloroethylene (1,1-DCE) contamination detected in the groundwater above the aquifer water quality standards at the landfill monitoring wells were studied by the City of Phoenix, ADEQ, and EPA in 1998. It was determined by EPA and ADEQ in January of 1999 that the 1,1-DCE contamination is originating from an upgradient source, and that the Nineteenth Avenue landfill is not contributing. Therefore, under the Consent Decree, the City of Phoenix is not responsible for addressing this contamination. The existing 1,1-DCE groundwater contamination will be considered for further investigation under ADEQ's Water Quality Assurance Revolving Fund (WQAZF) or "state Superfund" program. The wells at the landfill continues to be monitored as part of the Groundwater Contingency Plan (described above). Recently, levels of vinyl chloride above aquifer water quality standards were detected at the landfill monitoring wells. The City of Phoenix reports that this is due likely to the degradation of the 1,1-DCE. The City of Phoenix, ADEQ, and EPA are currently studying the issue.

The first Five-Year Review for the Site was conducted from January 2000 through June 2000 by ADEQ and approved by EPA September 2000. The Five-Year review is required by CERCLA Section 121 (c) due to the fact that hazardous substances, pollutants, and contaminants remain at the site at levels that preclude unlimited land use. A review of the protectiveness of this remedy is required no less frequent than every five years. The start of construction activities on August 14, 1995 triggered the deadline for this review. The next review will be due no later than five years after completion of the first review, or in September 2005.

The Five-Year Review consisted of the following activities: a review of relevant documents; interviews with appropriate operations staff, state and local federal agencies, local government officials, and concerned community members; applicable, relevant, and appropriate (AZAZ) review of current standards to the remedy; and a site inspection. In addition, a public notice regarding the completion of the review was placed in the local newspaper, and a copy of the completed report has been made available at the ADEQ file room and the local site repository (City of Phoenix public library).

The primary findings of the review were that a protectiveness determination for the remedy could not be made until additional data is obtained. However, several deficiencies were noted, which had the potential to affect current protectiveness. A follow-up report was required to investigate the deficiencies and determine whether the remedy is protective. The Follow-up report was completed in September 2001, and concluded that the remedy does remain protective of human health and the environment. However, additional recommendations were made to ensure protectiveness in the future. The most significant deficiencies in the five-year review requiring action are as follows:

• Due to high methane levels in certain methane probes at the landfill, the City of Phoenix (COP) was required to conduct monthly surface monitoring measurements in those areas according to an approved plan, and enhance the methane recovery systems to ensure the methane is not allowed to migrate beyond landfill boundaries at both cells. The COP has completed construction on the enhancements of the methane gas collection and treatment system and installation of new methane monitoring probes. The project construction was completed in August 2002, and system operations have reduced methane levels at the boundary of the landfill to safe levels.
• Several groundwater monitoring standards outlined in the Groundwater Contingency plan are not longer protective, and ADEQ will need to require new standards. The groundwater quality at the landfill however, is not exceeding any of the new groundwater standards, therefore no specific action is required by the COP. ADEQ is currently considering revising the Record of Decision (ROD) through an Explanation of Significant Differences to update the groundwater monitoring program requirements.

Pre-final inspections were conducted to determine the substantial completion of the project. A pre-final inspection of the gas collection system and flare stations was performed on December 4 and 5, 1996. Inspections for the other features of the project, including the completed levees and channelization of the Salt River, were conducted on December 6 and 12, 1996. Based on the results of the inspections, the project was determined to be substantially complete on December 6, 1996. Based on the results of two additional inspections conducted on January 7 and February 13, 1997, final project acceptance, by the City to the construction contractor, was made on February 28, 1997.

Based on the information gathered during the RI/FS and the quality of the construction of the final remedy, it is believed that the final remedy selected by ADEQ and EPA for the Nineteenth Avenue Landfill site is protective of human health and the environment, is cost effective and attains federal and state requirements that are applicable or relevant and appropriate. ADEQ issued written approval of completion of the remedial action in accordance with the Consent Decree on June 30, 1997 which activated the groundwater contingency plan.

The remedy uses permanent solutions and alternative treatment technologies to the maximum extent practicable for this site. The collection and flaring of gas and the activation of a groundwater contingency plan are significant components of the remedy; however, the size of the landfill and the volume of landfill wastes preclude a remedy in which contaminants could be effectively excavated and treated.

As this remedy will result in hazardous substances remaining on-site above health based levels, a review will be conducted by ADEQ and EPA at least every five years after commencement of remedial action to ensure the remedy continues to provide adequate protection of human health and the environment. The first of these reviews was completed in September 2000. Since there was insufficient data available to make a final determination on protectiveness to human health and the environment, additional data was collected, and supplemental report was completed in September 2001.

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

City of Phoenix Public Library
1221 N. Central Avenue
Phoenix, AZ 85004
(602) 262-6801

Arizona Department of Environmental Quality (ADEQ)
1110 W. Washington St.
Phoenix, AZ
(602) 771-4380

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) 536-2000

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

EPA SITE MANAGER:

Nadia Hollan

ADDRESS:

US EPA Region 9
75 Hawthorne St. (SFD-8-2)
San Francisco, CA 94105

PHONE NUMBER:

(415) 972-3187
or toll free message 1-800-231-3075

E-MAIL ADDRESS:

hollan.nadia@epa.gov

EPA COMMUNITY INVOLVEMENT COORDINATOR:

Jackie Lane

ADDRESS:

US EPA Region 9
75 Hawthorne St (SFD-3)
San Francisco, CA 94109

PHONE NUMBER:

(415) 972-3236
or toll free message at 1-800-231-3075

E-MAIL ADDRESS:

lane.jackie@epa.gov

PUBLIC INFORMATION CENTER:

(415) 947-8701

E-MAIL ADDRESS:

r9.info@epamail.epa.gov

STATE CONTACT:

William DePaul (Project Manager)
depaul.william@ev.state.az.us

Tina Wesoloskie (Community Involvement)
wesoloskie.tina@ev.state.az.us

ADDRESS:

ADEQ
1110 W. Washington St.
Phoenix, AZ 85007-2935

PHONE NUMBER:

William (602) 771-4654
Tina (602) 2074288

PRP CONTACT:

Ron Serio

ADDRESS:

City of Phoenix, Public Works Department
101 South Central Ave., S-312
Phoenix, AZ 85004

PHONE NUMBER:

PH. (602) 256-5600

COMMUNITY CONTACT:

ADDRESS:

PHONE NUMBER:

State Environmental Protection Agency

US Environmental Protection Agency

(800) 852-7550

(800) 424-8802

STATE:

AZ

CONGRESSIONAL DISTRICT:

04

EPA ORGANIZATION:

SFD-8-2

• Site Description and History

•  Maps
•  Images

•  Description
•  Environmental Data

•  Response Action Status

EPA SITE MANAGER:

ADDRESS:

PHONE NUMBER:

E-MAIL ADDRESS:

EPA COMMUNITY INVOLVEMENT COORDINATOR:

ADDRESS:

PHONE NUMBER:

E-MAIL ADDRESS:

PUBLIC INFORMATION CENTER:

E-MAIL ADDRESS:

STATE CONTACT:

ADDRESS:

PHONE NUMBER:

PRP CONTACT:

ADDRESS:

PHONE NUMBER:

COMMUNITY CONTACT:

ADDRESS:

PHONE NUMBER:

STATE:

CONGRESSIONAL DISTRICT:

EPA ORGANIZATION:

source: U.S. Environmental Protection Agency

see also:

Nineteenth Avenue Landfill Environmental Pollution in Arizona- Site: Nineteenth Avenue Landfill
Nineteenth Avenue Landfill Superfund Site Info

Williams Air Force Base Environmental Pollution in Arizona- Site: Williams Air Force Base
Williams Air Force Base Superfund Site Info

AZ Environmental Pollution Lawsuit: Arizona Superfund Sites
Environmental pollution Superfund Sites in Arizona