2024: ADEQ conducted groundwater sampling activties, cap inspection, and a site review.

2021 – 2023: ADEQ conducted groundwater remediation and sampling at the site. ADEQ also performed cap inspections.

2020: ADEQ conducted groundwater remediation activities at the site.

2019: ADEQ implemented the remedy which included monitoring and maintenance of the existing asphalt cap, enhanced reductive dechlorination (ERD) groundwater treatment, and monitored natural attenuation (MNA).

2018: The Record of Decision was signed.

2017: The Proposed Remedial Action Plan (PRAP) was issued for public review and comment in July. The proposed remedy for the site is monitoring and maintenance of the engineered asphaltic concrete cap and in situ ERD with MNA.

2016: A downgradient deep monitor well was installed in January. ADEQ completed one round of ground water monitoring and sampling at the site. Contaminant of concern concentrations and distribution in the aquifer remained relative constant. The Feasibility Study report was released in September.

2015: During March 2015, ADEQ completed one round of ground water monitoring at the site. Tetrachlorethene (PCE) concentrations and distribution in the upper part of the aquifer remained relative constant with the highest PCE concentration detected at a concentration of 54 parts per billion (ppb). In the middle portion of the aquifer, PCE concentrations and distribution also remained relatively constant with the exception of one well where concentrations continued to rise and PCE was detected at 1000 ppb. The Arizona Aquifer Water Quality Standard for PCE is 5 ppb.

In the upper part of the aquifer, cyanide concentrations remain above the Aquifer Water Quality Standard (AWQS) of 200 ppb in one monitor well. In the middle part of the aquifer, cyanide is present at 200 ppb in one monitor well. Cyanide concentrations in the middle part of the aquifer continue to separate from the source area.

No contaminants were detected above standards in the deeper part of the aquifer. 

2014: ADEQ installed seven additional soil vapor monitor wells at the site. A round of soil vapor sampling was also conducted. Soil vapor samples were analyzed for hydrogen cyanide and volatile organic compounds including PCE and trichloroethene (TCE). No samples detected hydrogen cyanide. PCE and TCE were detected a concentrations below ADEQ’s suggested soil vapor screening levels. ADEQ completed the draft Remedial Investigation (RI) report and solicited comments on the draft RI and on the Proposed Remedial Objectives. The Final RI Report was released in October. Groundwater monitoring was conducted annually at the site.

2013: ADEQ completed the installation of a permanent asphalt-based cap over the cyanide impacted soils. This cap limits people's access to these soils and further impacts to the groundwater beneath the site by minimizing the amount of cyanide leaching from cyanide-contaminated soils. ADEQ installed three additional wells down gradient of the site and the horizontal and vertical definition of the plume is complete. Groundwater monitoring was conducted annually at the site.

2012: ADEQ continued to investigate the site to identify the extent and severity of the groundwater contamination. ADEQ finalized plans to install a permanent asphalt-based cap over the cyanide-impacted soils still remaining at the site below a depth of one foot. 

2009 – 2011: A soil vapor investigation was performed which included the installation of several permanent soil vapor monitor probes and a soil vapor survey in order to help identify potential source areas. Additional permanent soil vapor monitor probes were installed and groundwater samplings were conducted. ADEQ continued to investigate the site to identify the extent of the groundwater contamination. Groundwater sampling results indicate the PCE plume extended over 4,000 feet downgradient from the site.

2008: ADEQ installed one groundwater extraction well in the middle of the contaminant plume. An aquifer test was completed to determine aquifer characteristics. The last remaining septic system on the Houston International, Limited (HIL) property was taken out of service and replaced with a new system and leach field located away from contaminated soil. Additional information was gathered north of the HIL property to locate potential sources areas. 

2007: Installation of additional deep groundwater monitor wells indicated that groundwater was present in three distinct zones: shallow (50 to 90 feet below ground surface [bgs]); middle (105 to 170 feet bgs) and deep (starting at 170 feet bgs). Each zone is divided by separate clay units. Groundwater samples from each zone indicated that the majority of the contaminant plume was located within the middle zone.

2005 – 2006: ADEQ drilled and sampled ten additional groundwater monitor wells to further define the extent of the contaminant plume. Laboratory analyses from these monitor wells indicated that the contaminant plume extended approximately ½ mile downgradient of the site.

2004: ADEQ collected indoor air data from the buildings on the property and one building adjacent to the property. This data was collected as part of an ongoing risk assessment of the indoor air at the site. ADEQ also drilled and sampled four deep borings beneath two of the remaining septic tanks and the former disposal pond area. The purpose of these borings was to evaluate the cyanide contamination at depth in these areas. Cyanide contamination above the non-residential soil remediation level (SRL) extended to a depth of approximately 17 feet bgs in some areas of the site. ADEQ used these data and other information to develop groundwater protection levels for the cyanide contaminated soils remaining in place.

Also, ADEQ drilled and sampled two deep groundwater monitor wells at the site. Analysis of groundwater samples from these deep wells did not indicate PCE or cyanide contamination above an AWQS.

2003: Soil and soil vapor samples were collected from six borings at the site. Samples were collected to evaluate the vertical extent of PCE contamination. Sampling results indicated that the concentrations of PCE remaining in the soil did not exceed regulatory standards.

2002: ADEQ completed an early response action (ERA) at the site, which included excavation and disposal of the upper foot of cyanide-contaminated surface soils. Approximately 1,700 tons of contaminated soils were removed from the site. A one-foot cap of aggregate base coarse material was placed over the remaining cyanide-contaminated soils. This cap helps prevent direct exposure to the underlying contaminated soils remaining at the site. The ERA also included the removal of two unused sumps and the cleaning of three active septic systems at the site. Approximately 15,000 gallons of PCE and cyanide-contaminated wastewater and sludge were removed from the disposal system during cleaning operations. The removal of this source material addressed a continuing source of groundwater contamination.

1998 – 2000: In 1998, the ADEQ Hazardous Waste Section (HWS) referred the facility to the ADEQ Superfund Programs Section, Site Assessment Unit. The site was placed on the WQARF Registry in March 2000 with a score of 31 out of a possible 120.

1996: One nested groundwater monitoring well (MW-102) and one upgradient monitor well (MW-101) were installed at the site. The maximum PCE concentration detected was 520 micrograms per liter (μg/l) in MW-2 at 140 to 150 feet bgs.

1990 – 1994: HIL reported a leaking tank to the ADEQ Underground Storage Tanks (UST) Section. The ADEQ UST Section referred the facility to the ADEQ Water Pollution Compliance Unit. Consultants for HIL conducted soil and groundwater investigations under the oversight of the Water Pollution Compliance Unit.

In 1990, PCE and metals were detected in onsite soils. Subsequent soil investigations indicated that PCE was present in soil at concentrations below the Arizona residential SRL of 53,000 micrograms per kilogram (μg/kg). In 1991, HIL began to use Industroclean (which contains ethylene glycol monobutyl ether) in place of PCE. Consultants for HIL installed three groundwater monitor wells (MW-1, MW-2, and MW-3) and performed groundwater sampling in 1993. The PCE concentrations exceeded the AWQS for PCE of 5.0 μg/l.

Also in 1993, the ADEQ HWS inspected the facility, and in 1994, HIL and the ADEQ HWS entered into a compliance order. Consultants for HIL conducted additional soil and groundwater investigations under the compliance order. In 1994, a soil vapor survey was conducted. Elevated concentrations of PCE were present in the soil vapor samples. TCE and 1,1,1-trichloroethane were also detected in soil vapor samples. HIL moved its motion picture laboratory operation off-site. The facility was subsequently occupied by the offices of Houston Film Labs and a dance studio. This operation did not generate wastewater.

1966 – 1988: Houston Photo Products (HPP) operated a motion picture laboratory and a facility, which also manufactured photographic film and paper processing equipment for the photo industry.  In 1988, HPP changed its name to HIL. The chemicals used at the facility included standard photographic chemicals, namely PCE, and small amounts of various other photographic chemicals and water. The wastewater at the facility was treated to recover silver. The treated wastewater was disposed in three ways:

Some of the wastewater was discharged to a 1,000-gallon concrete underground sump on the east side of the property.  When this sump was full, it was discharged to a disposal pond on the east side of the property. Wastewater from this disposal pond overflowed onto the adjacent property to the east of the site. Wastewater was used to water plants in landscaped areas at the front of the building. Wastewater was discharged to the ground in the southwest portion of the property by a sprinkler system and later to a sump.

Beginning in 1975, HPP/HIL used PCE to clean stainless steel machine parts. On one occasion in 1978, PCE was discharged to the 1,000-gallon concrete underground tank.