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NIBW Superfund Site: Miller Road Treatment Facility

NIBW Superfund Site: Miller Road Treatment Facility


The Miller Road Treatment Facility (MRTF) is a groundwater treatment facility owned and operated by EPCOR Arizona, formerly known as the Arizona American Water Company, successor to the Paradise Valley Water Company. The MRTF is located just south of McDonald Drive on Cattletrack (formerly Miller) Road in Scottsdale, Arizona. The plant provides treatment to remove trichloroethylene (TCE) from groundwater extracted from the lower alluvial unit in the southernmost wells of the EPCOR well field.

The MRTF was designed and constructed collaboratively and voluntarily by EPCOR’s predecessor, the Paradise Valley Water Company and the NIBW Participating Companies (PCs) after low level concentrations of TCE were detected in monitor wells sited approximately 3,500 feet south of the current EPCOR well field in 1994. Construction of the MRTF began in March 1996 and the plant was operational in March 1997, about two years before TCE was detected in the southernmost EPCOR extraction well, PV-15.

The construction was reviewed by the Environmental Protection Agency (EPA) and the Arizona Department of Environmental Quality (ADEQ). The NIBW PCs provided funding for design and construction and continue to fund ongoing operation and maintenance of the MRTF.

In 2003, the EPA included groundwater extraction and treatment at MRTF as part of the required remediation efforts at the NIBW Site in the Amended Consent Decree and established operational requirements. The MRTF currently provides treatment for EPCOR wells number PV-14 and PV-15.  It was previously used to treat groundwater from well PCX-1, a well owned and operated by the Salt River Project (SRP). Together with the other companies involved, Motorola Solutions worked closely with SRP to install PCX-1 on the Arizona Canal bank approximately 3,500 feet south of the southernmost EPCOR well to extract groundwater containing TCE before it reached the EPCOR well-field. The MRTF is capable of treating around 6,300 gallons per minute of groundwater.  Water extracted from well PCX-1 is now treated at a facility known as the NIBW Granular Activated Carbon (GAC) Treatment Facility (NIBW), commissioned in 2013.

There are three treatment towers at the MRTF, each capable of treating around 2,100 gallons per minute of water. The treatment towers installed at MRTF use packed tower aeration (air stripping treatment technology) to reduce influent the TCE concentration to levels that meet or surpass drinking water standards. The water enters the top of the treatment tower and TCE is removed from the water as it flows over the packing material and contacts air passing upward through the column. A blower at the base of the column introduces up to 10,500 cubic feet per minute of air in counter-current flow through the column from where it flows to the granular activated carbon vapor phase treatment system as necessary. The treated water from the column flows into a clearwell beneath the MRTF and is then pumped to another EPCOR facility where it is disinfected using a hypochlorite solution, blended with water from other EPCOR groundwater wells and treated through an arsenic removal process prior to use in the EPCOR distribution system. Alternatively, the water may at times be distributed to the Arizona Canal for Salt River Project use. Treated water from the MRTF is routinely below the TCE detection limit of 0.5 ug/L.

At the start of the MRTF groundwater extraction and treatment program in 1997, together with the other companies involved, Motorola Solutions initiated a comprehensive monitoring program for the Paradise Valley area. The monitoring program and subsequent state-of-the-art groundwater modeling indicate that the MRTF extraction wells will capture impacted groundwater in the lower alluvium unit. Since the MRTF became operational in 1997 through 2012, more than 94 billion gallons of groundwater have been treated and returned to beneficial use.

About EPCOR Water company

EPCOR Water Arizona is owned by EPCOR Utilities, and is privately owned by the City of Edmonton, Canada.  EPCOR Utilities is an integrated energy provider, supplying water, wastewater, and power distribution services to more than 1 million customers across Western Canada and the United States. In 2012 EPCOR Water bought Arizona American Water Company.  EPCOR water provides potable water service to 11 water utility districts in Arizona. Within the City of Scottsdale, Town of Paradise Valley and unincorporated areas of Maricopa County it serves approximately 4,700 connections (approximately 10,000 people). The sole source of groundwater for these municipalities is pumped from six wells located immediately west of the Arizona Canal between Lincoln Drive and McDonald Drive in Scottsdale, and an allotment of Colorado River Water from the Central Arizona Project. (See attached map of EPCOR service area.)