Motorola 52nd Street | Site History : Page 2 of 3

OU2

1983: ADEQ discovered groundwater contamination in the area known today as OU2. TCE was detected at the Desert Hills Well (Monroe and 27th Street) at 640 ppb, at the security center well (Central Avenue and Van Buren) at 202 ppb, and at the Eastlake Park well (Jefferson and 16th Street) at 44 ppb. At the time of discovery, it was not known that Motorola’s contamination extended beyond the Old Cross Cut Canal. Therefore, the contamination discovered in this area was initially thought to be a separate contaminant plume known as the East Washington (EW) area.

1985: From 1985 to 1989, ADEQ conducted an RI and initiated an investigation of PRPs. In 1987, the EW area was listed on ADEQ’s Water Quality Assurance Revolving Fund (WQARF) priority list. The study area boundaries were determined to be Thomas Road to the north, Lower Buckeye Road to the south, 48th Street to the east, and 7th Avenue to the west.

1988: In July, questionnaires were mailed to 995 facilities located in the EW area requesting information regarding their hazardous substance use, storage, and disposal practices. In August 1989, ADEQ completed the Phase I report for the EW area. Questionnaire responses were evaluated by ADEQ to determine which facilities warranted additional investigations. At the time, four companies were found to have potential sources of contamination that may have contributed to the groundwater plume: Tiernay Turbines (now Walker Power Systems), Arvin Industries, FMC Corporation, and AlliedSignal (now Honeywell).

1990 – 1992: ADEQ and Motorola continued an area-wide groundwater investigation to define the extent of groundwater contamination in the OU2 area. Area-wide sampling events were coordinated to include Motorola wells and EW wells. The extent of groundwater contamination prompted ADEQ and EPA to develop a second OU to address groundwater contamination before a final remedy is selected. Motorola submitted the RI report to ADEQ which confirmed that contamination migrating from the Motorola facility had extended into the EW area. ADHS completed a Baseline Risk Assessment that concluded: The risk of public exposure to groundwater is limited, and therefore causes no imminent health hazard. EPA completed an ecological risk assessment that concluded: . . . because of [the VOC’s] high volatility and low toxicity relative to freshwater aquatic criteria, exposure of biota to acute or chronic levels of TCA and TCE may not be a concern. Inorganics (arsenic and lead) would be of most concern to biota because of their exceedance of the fresh water criteria, persistence in the environment, and their potential for bioaccumulation. During this year EPA named additional PRPs: AlliedSignal (now Honeywell), ITT Cannon, and Tiernay Turbines (now Walker Power Systems).

1993: In 1993, EPA named the City of Phoenix a PRP as the landowner of a portion of the Honeywell and ITT Cannon properties. In August, Motorola submitted a draft Interim Remedy FS report which covers the same area as the final Remedy RI report. Sixty-seven remedial alternatives were evaluated and ROs were proposed. The document was approved by ADEQ in January 1994. ATSDR completed an update to the 1988 Health Assessment.

1994: In July, ADEQ and EPA issued the ROD selecting the interim groundwater remedy. The purpose of the OU2 interim remedy is to provide additional containment of contaminated portions of the groundwater. The interim remedy included groundwater extraction near 20th and Washington Streets, treatment of the water by ultraviolet oxidation and granular activated carbon (GAC), and discharge of the treated water to the Grand Canal for irrigation use.

1996: ATSDR completed an update to the 1988 Health Assessment and the 1993 update to the Health Assessment. In October, Motorola and the City of Phoenix signed a Consent Decree (CD with ADEQ to implement the design of a groundwater containment and treatment system for OU2. Honeywell withdrew from the agreement and did not participate in the design.

1997: ADEQ and EPA determined that the investigation of groundwater contamination from 52nd Street to 7th Avenue would continue under the federal Superfund program. The EPA delegated its authority to ADEQ to continue to be the lead agency for the OU2 area.

1998: In November, EPA issued a Unilateral Administrative Order (UAO) to Motorola and Honeywell (the Companies) for construction, start up, and two years of operation and maintenance of the groundwater treatment system. EPA became the lead agency for the remedial action phase for OU2.

1999: On December 28, ADEQ approved the final 100% design report. In November, the Companies submitted the OU2 Remedial Action Work Plan to EPA.

2000 –  2001: In March 2000, under the oversight of EPA, construction of the treatment system began and was completed in September 2001. The OU2 groundwater treatment system became fully operational, designed to pump at a rate of approximately 5,000 gallons per minute (gpm). The treated water is discharged to the Salt River Project Grand Canal for irrigation use and met all treatment standards.

2002: In November, Motorola submitted an evaluation of groundwater extraction rates by conducting a model. The results of the model indicated that the extraction rates of the OU2 system can be substantially reduced while still maintaining capture of the observed plume. The pumping rate was reduced to 2,650 gpm.

2003: In April, the companies submitted the Remedial Action Report. The report provided documentation to show that the OU2 groundwater treatment system has attained capture of the contaminant plume.

2005: ADEQ issued a UAO to Joray Corporation to conduct an investigation at its former facility, Kachina Testing Laboratories.

2006: As of January, the OU2 capture and treatment system treated over 4.5 billion gallons of water and removed over 6,000 pounds of contamination. The second FYR was completed in September.

2007: The companies installed four sets of groundwater monitor wells to the south and west of the southern most groundwater extraction well. Three additional locations were drilled during the month of November to evaluate groundwater elevations, contaminant concentrations, and bedrock.

2008: As of September 30, the OU2 groundwater treatment system treated over 7.6 billion gallons of groundwater and removed over 10,567 pounds of contamination since the system began operation in December 2001.

2009 – 2010: The Companies negotiated a CD with ADEQ for operation of the OU2 treatment system and for ADEQ to take over oversight from EPA. In July 2010, the decree was approved by the Federal District Court in Phoenix. As of the end of September 2010, approximately 12,334 pounds of VOCs have been removed from the subsurface.

2011: A FYR was completed evaluating the record of decision and the remedy in place. The hydrostratigraphic nomenclature of Subunit A, B and C was changed to Salt River Gravels and Basin Fill. Groundwater monitoring continued and the treatment system operated without disruption.

2012: ADEQ began negotiating the statement of work and the AOC for the OU2 site-wide area. The RI/FS will address groundwater monitoring data gaps and investigation of the vapor intrusion pathway.

2013: Negotiation of the OU2 supplemental RI/FS continued. The RI/FS will aid in determining a proposed plan and final remedy. An evaluation of vapor intrusion is needed to address this potential pathway. SVOCs were added to the Sept. sampling rounds for select wells.

2014: Six new monitoring wells were installed to address data-gaps within the COC plume.

1999 to 2017: Honeywell completed remedial actions at the Honeywell 34th Street facility (within OU2) for jet fuel releases over the course of approximately 18 years. Honeywell used multiple remedial tools to remove more than 7,500 gallons of free product (via direct recovery) and approximately 17 million pounds of petroleum hydrocarbons from the subsurface between 1999 and 2017 using biologically enhanced soil vapor extraction (BSVE) technology. In addition, the BSVE system removed over 400 pounds of residual chlorinated VOCs from the subsurface in the eastern portion of the facility.

2015 to 2017: As part of the RI, the VI investigation began in 2016 and continues to date. Semi-annual groundwater monitoring was performed and GETS continued operation to reduce the COC plume.

2018: The VI investigation continues with the 5th round of step-outs to fully define the extent of TCE in soil vapor at concentrations greater than the (site specific) Soil Gas Human Health Screening Level (SGHHSL) of 210 micrograms per cubic meter. An in-situ chemical oxidation (ISCO) pilot program work plan was approved and implemented in May. Approximately 40,000 pounds of chemical oxidant was initially injected into four wells and later into six supplemental wells near center and southern portion of the COC plume at the western end of OU2.