Silverbell Landfill

Registry placement date: April 23, 1999

Score: 51

County: Pima

Location: 3200 North Silverbell Road in northwest Tucson, approximately bounded by Sweetwater Drive on the north, Grant Road/Ironwood Hills Drive on the south, Interstate 10 on the east and Silverbell Road on the west and comprised of approximately 40 acres

Contaminants of concern: Tetrachloroethene (PCE), trichloroethene (TCE), cis-1,2-dichloroethene (cis-1,2-DCE) and vinyl chloride

Action taken: In 2001, the city of Tucson (COT) began operation of a full-scale soil vapor extraction (SVE) system to remove and treat contaminated volatile organic chemical (VOC) landfill gases contributing to the groundwater contamination. From December 2006 until 2008, the system operated intermittently to control methane migration. In April 2008, the system was shut down and the equipment was removed. COT conducts soil-gas rebound testing periodically.

In 2010, COT proposed to install a pump-and-treat (P+T) system to address most of the site plume. Since 2010, COT has been working on revisions (including conducting additional modeling) to this proposal. COT has concerns regarding the potential for the upgradient Kinder Morgan Silvercroft Wash Release (SWR) Voluntary Remediation Program (VRP) site methyl tertiary-butyl ether (MTBE) groundwater plume eventually reaching COT’s proposed P+T system, which will not address MTBE. ADEQ, COT and Kinder Morgan have been meeting periodically to improve coordination regarding sampling and cleanup of the two sites. 

Status: COT identified Geosyntec as the design, build and operate consultant for the groundwater P+T system. COT expects to have a contract agreement in place with Geosyntec by May 2016 and expects installation of the P+T to begin soon thereafter.

In April 2016, COT provided comments to Kinder Morgan and ADEQ on the draft SWR VRP Remedial Investigation report. COT has requested that ADEQ address the monitoring and remediation issues related to the migration of the SWR contaminants into the Silverbell Landfill WQARF site.

COT plans to install an additional groundwater monitor well to the northwest to assist in delineating the lateral extent of the groundwater plume.

Community Advisory Board (CAB): Not applicable under “old WQARF” laws/rules.