Revised On: Feb. 16, 2024 - 1:00 p.m.

2021: The enhanced reductive dechlorination (ERD) groundwater treatment pilot study continued throughout the year. Soil vapor extraction was performed intermittently at the former Maroney’s property. The Soil Vapor Extraction (SVE) system located at the former Viking's location was moved offsite.

2020: An ERD groundwater treatment pilot study was initiated in February 2020. The proposed remedial action plan (PRAP) was released in September 2020. Soil vapor extraction was performed intermittently at the former Maroney’s property.

2019: Rebound evaluations continued at both the Maroney’s Cleaners and Viking Cleaners SVE systems. The Draft Remedial Investigation (RI) Report was released in March.  The Proposed Remedial Objectives (RO) Report was released in May.  The Final RI Report and Feasibility Study (FS) Workplan were released in June. The Final FS Report was completed in September.

2018: Two additional wells, VCMW-24 and 26, were installed to delineate the downgradient extent of the plume. The SVE system at Maroney’s was shut down for a rebound evaluation. Concentrations remained below the health-protective concentrations during the rebound evaluation period and the system was not restarted. In December, an additional soil vapor extraction well (SVE-10) was installed at the former Viking Cleaners facility.

2017: Groundwater well drilling continued in an effort to fully delineate the plume, including drilling of VCMW-08AR and VCMW-23. Additional SVE wells and vapor probes were installed to assist ongoing SVE operations at both the Maroney’s and former Viking Cleaners facilities.

2016: Several groundwater wells and borings were installed to further delineate the plume including VCMW-03B, 06B, 15-17, 20, and 22. A rebound evaluation and remediation optimization review was conducted for the Maroney’s SVE system. The Viking SVE system operated for much of the year with only brief shutdown periods for maintenance and operational considerations. In December, the Arizona Department of Health Services (ADHS) published a Health Consultation and concluded that there is no inherent public health concern from subsurface PCE or trichoroethene (TCE) vapor concentrations.

2015: A total of four groundwater and five soil vapor monitor wells were installed throughout the site. Design and implementation of SVE remediation systems was initiated as part of an early response action (ERA) near the Maroney’s Cleaners and the former Viking Cleaners. The Maroney SVE system has been turned off due to low soil vapor concentrations. The Viking SVE system is operating. Site investigation and groundwater well installation continued throughout FY16.

In FY 2015, a total of 117 pounds of Volatile Organic Compounds (VOCs) were removed at the Maroney and Viking SVE system sites. Additionally, 183 groundwater, 19 soil vapor, and 38 soil samples were collected.

2014: Construction of the SVE systems located near the former Viking’s Cleaners facility was completed in the summer of 2014. A total of 13.075 pounds of volatile organic compounds (VOCs) were removed from the Maroney’s SVE system. Additionally, 68 groundwater and 326 soil vapor samples were collected.  Follow-up indoor air samples were also collected to further assess the potential for vapor intrusion.

2013: The SVE system near Maroney’s Cleaners became operational in June.  Additionally, ADEQ installed soil vapor wells to help delineate the soil vapor plume along the eastern portion of North 32nd Street between East Indian School Road and East Glenrosa Avenue, and at the corner of East Indian School Road and North 31st Street. Soil vapor wells were also installed along the southern portion of the Viking facility.

Soil vapor samples showed concentrations of PCE varied significantly from location to location. PCE was detected in soil vapor at concentrations as high as 4,100 micrograms per cubic meter (µg/m³). The results of soil vapor sampling delineated an area in which PCE concentrations exceeded vapor intrusion screening levels calculated from available EPA guidance. Based on this information, ADEQ went door-to-door to collect indoor air samples from residences located above the soil vapor plume to assess the potential for vapor intrusion. Sample results did not indicate a wide-spread vapor intrusion problem.

2012: ADEQ installed three SVE wells at the former location of Viking Cleaners in preparation for the installation of a SVE system. Eleven SVE wells and eight groundwater remediation pilot test wells were installed along East Fairmont Avenue and North 31st Street. An additional groundwater monitoring well was installed south of Fairmont Avenue on 30th Street.

By February, 12 SVE extraction wells and 10 SVE observation wells were installed in preparation for the installation of a SVE system near the Maroney’s Cleaners facility.

During the spring, ADEQ also conducted sampling of the soil vapor monitoring wells throughout the site. Cone Penetrometer Testing (CPT) was also performed throughout the site to investigate current hydrogeologic conditions. Additionally, a routine groundwater monitoring event was conducted. 

2011: ADEQ installed five permanent soil vapor monitoring wells at the former location of Viking Cleaners. The initial soil vapor samples collected from these wells had PCE and TCE concentrations that ranged from less than the laboratory’s reporting limit to 350,000 µg/m³ and 2,400 µg/m³, respectively. ADEQ also installed two SVE test wells, and 10 SVE observation wells and conducted an SVE pilot test. The results from the test suggest that SVE could be an effective treatment technology at the former location of Viking Cleaners.

In May, ADEQ installed a groundwater monitoring well west of the former location of Viking Cleaners within the parking lot adjacent to Food City. The initial groundwater sample collected from the well had a PCE concentration of 1,100 micrograms per liter (µg/L).

Based on the soil vapor sampling results in 2010 along East Fairmont Avenue and North 31st Street, ADEQ installed two SVE test wells, six SVE observation wells and conducted SVE pilot tests in February and December. The results from the tests suggested that SVE could be an effective treatment technology along East Fairmont Avenue and North 31st Street.

In April, 10 permanent soil vapor monitor wells were installed north of the Maroney’s Cleaners facility. The initial soil vapor samples collected from these wells had PCE and TCE concentrations that ranged from less than the laboratory reporting limit to 300,000 µg/m³ and 3,800 µg/m³, respectively. As a result, ADEQ conducted an SVE pilot test in June. The results from the test suggested that SVE could be an effective treatment technology at the Maroney’s Cleaners facility.

During a routine groundwater monitoring event, PCE was not detected in the SRP well above the Arizona Water Quality Standard (AWQS).

2010: ADEQ continued to collect passive soil gas samples from an additional 25 locations placed within one and a half city blocks west to southwest of the former location of Viking Cleaners. The qualitative PCE mass observed in those samples ranged from less than 25 nanograms (ng) up to 546 ng. ADEQ also installed 21 permanent soil vapor monitoring wells along East Fairmont Avenue and North 31st Street. The initial soil vapor samples collected from these wells had PCE and TCE concentrations that ranged from less than the laboratory’s reporting limit to 36,000 µg/m³ and 210 µg/m³, respectively.

During a routine groundwater monitoring event, PCE was not detected in the SRP well above the AWQS.

2008: The SVE//Air Sparging (AS) system at the former location of Viking Cleaners had removed approximately 3,020 pounds of PCE. Since the treatment system had reached the appropriate cleanup criteria, the system was shut down and removed from the site. In June, ADEQ installed a second groundwater monitoring well located west of the former dry cleaning building within East Fairmont Avenue. The initial groundwater samples collected from the well had shallow and deep PCE concentrations that ranged from 32 to 2,400 µg/L.

ADEQ collected passive soil vapor samples from 40 locations placed within one city block west to southwest of the former location of Viking Cleaners. The qualitative PCE mass observed in those samples ranged from less than 25 ng up to 66,800 ng.

During a routine groundwater monitoring event, PCE was not detected in the SRP well above the AWQS.

2007: In May, a groundwater monitoring well located south of the Maroney’s Cleaners facility was installed. The initial groundwater samples collected from the well had shallow and deep PCE results that were below the AWQS of 5 µg/L. In June, ADEQ sent out notices per A.R.S. §49-287.03 initiating the RI for the site. The SVE/AS system located at the former location of Viking Cleaners remained operational. 

2006: An ERA investigation was conducted to determine what contamination remained in soil and groundwater near the Maroney’s Cleaners facility. Three additional groundwater monitor wells were installed within the parking lot area surrounding the Maroney’s Cleaners facility. The initial groundwater samples, collected from the three wells, indicated a maximum PCE concentration of 100 µg/L. Soil vapor samples collected during the monitor well drilling had a maximum PCE concentration of 468 µg/L in one well at a depth of 5 feet below ground surface (bgs).

In the spring, as part of a Prospective Purchaser Agreement (PPA), the new property owner of the former location of Viking Cleaners installed four soil vapor extraction wells inside the building. The wells were then connected to the SVE/AS system being operated by ADEQ. ADEQ installed a groundwater monitoring well located west of the building. The initial groundwater samples collected from the well had shallow and deep PCE concentrations of 2.9 and 2.7 µg/L, respectively.

During a routine groundwater monitoring event, PCE was detected in the SRP well at a concentration of 5.0 µg/L, while the maximum PCE concentration observed in a groundwater monitor well southwest of the SRP well was 930 µg/L.

2004: A SVE/AS system was installed at the former location of Viking Cleaners. The SVE/AS unit became operational in December.

During a routine groundwater monitoring event, PCE was detected in the SRP well at a concentration of 4.6 µg/L, while the maximum PCE concentration observed in a groundwater monitor well southwest of the SRP well was 12,900 µg/L.

2003: In March, an ERA investigation was conducted at the former location of Viking Cleaners at 4029 N. 32nd Street. The ERA included completion of four soil borings (two inside and two outside the former dry cleaning building) and the collection of soil vapor and a groundwater sample. Results of this investigation indicated that a release of PCE had occurred and that the release had impacted groundwater. In April, air samples were collected from inside this building and the adjacent convenience mart. ADHS evaluated this data and provided a health consultation that determined there was no risk to employees under current use scenarios.

During a routine groundwater monitoring event, PCE was detected in the SRP well at a concentration of 8.1 µg/L, above the AWQS of 5.0 µg/l. The maximum PCE concentration observed in a groundwater monitor well west of the SRP well was 3,600 µg/L.

2000: In May, the site was placed on the WQARF Registry with a score of 29 out of a possible 120. In June, a limited Phase II investigation was conducted at the Maroney’s Cleaners facility located at the northwest corner of 32nd Street and Indian School Road. The investigation included a soil vapor survey to 15 feet bgs and the installation and sampling of two groundwater monitor wells. The highest concentration of PCE detected in soil vapor was 15,000 µg/L from a sample collected at 15 feet bgs in the alley just north of Maroney’s Cleaners. The highest detection of PCE in groundwater, 28 µg/L, was observed southwest of Maroney’s Cleaners in the parking area.

1983 – 1998: Groundwater samples were collected by SRP from their well, 17.0E-8.0N, located southwest of 3201 E. Indian School Road (formally Unocal #6453). A sampling event, conducted in January 1996, yielded the highest detection of PCE yet observed in the SRP well, a concentration of 82 µg/L.

1989 – 1994: Two underground storage tanks were removed from Unocal #6453, formerly located at 3201 E. Indian School Road. During an investigation in 1994, a sample of the sludge, from the western waste oil tank, was analyzed and contained 68 milligrams per kilogram (mg/kg) of PCE. Additionally, a soil sample collected from a depth of 12 feet bgs beneath the same tank contained 13 mg/kg of PCE.

1989: Soil gas surveys were conducted at multiple facilities throughout the East Central Phoenix study area to determine if a release of contaminants to the subsurface had occurred.