Payson PCE

Registry placement date: April 29, 1998

Score: 63

County: Gila

Location: Payson, approximately bounded by Main Street to the north, Cedar Lane to the south, Beeline Highway (State Route 87) to the east and McLane Road to the west

Contaminant of concern: Tetrachloroethene (PCE) 

Action taken: An interim groundwater treatment system (IGTS) was constructed to remediate the contamination in the source area. The IGTS operated from October 1998 to January 2003 and was decommissioned in July 2013.

An expanded groundwater treatment system (EGTS) began operation in October 1998 and continues to operate by treating contaminated water and preventing the contamination plume from migrating further. Treated water from the EGTS is delivered to the town of Payson’s drinking water system.

ADEQ completed the record of decision (ROD) in June 2007. Groundwater monitoring takes place twice per year. The periodic site review was completed in November 2013. In December 2013, to optimize mass removal, two additional monitor wells were connected to the production well network of the EGTS. Both production wells started pumping in January 2014.

Status: In 2015, a remedial optimization evaluation indicated enhanced reductive dechlorination (ERD) would accelerate remediation. Substrate injections (bio-stimulation) were planned based on the most current groundwater sampling at the site and injections were completed at four newly installed injection wells.  Substrate injections were completed in September 2016 and February 2017.  One bio-augmentation injection was completed in May 2017. The performance monitoring data demonstrate effective treatment of the source area with ERD; current PCE concentrations in wells all four injection wells are all less than the aquifer water quality standard (AWQS) of 5 micrograms per liter (µg/L) for PCE. Currently, only two groundwater wells exceed the AWQS. ADEQ will continue to conduct groundwater monitoring events and evaluate data to determine the next step towards closure of this WQARF site. The town of Payson will continue to operate and maintain the EGTS. 

Community Advisory Board (CAB): Not active