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Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Evoqua Water Technologies
(formerly Siemens Carbon Regeneration Facility)


National Historic Preservation Act


US EPA has made a Determination of No Historic Properties Affected by a Resource Conservation and Recovery Act (RCRA) permit decision at the Evoqua Water Technologies facility in Parker, Arizona. This means that whether EPA approves or denies Evoqua’s permit application, there would be no impact on historic properties. This fact sheet summarizes this determination and its relationship to the hazardous waste permit being sought by Evoqua.


Evoqua Water Technologies, formerly Siemens Carbon Regeneration Facility, operates a spent carbon storage and treatment facility on the Colorado River Indian Tribes (CRIT) reservation, near Parker, Arizona. Evoqua treats spent carbon in a regeneration furnace to purify it and make it a reusable product that is sold back to their customers.

EPA is responsible under RCRA to permit facilities that manage regulated wastes on tribal lands. Evoqua has been operating under RCRA “interim status”, while applying for a RCRA permit. It is important to note that both the interim status and permit regulations require that the facility be operated safely, so as to protect both human health and the environment.

EPA is in the process of reviewing Evoqua’s application for a RCRA permit at the Parker, Arizona location. As part of that review, EPA has conducted a number of more detailed studies, some in conjunction with other governmental agencies. One of these is a National Historic Preservation Act (NHPA) review, which requires that EPA review potential impacts of the permit decision on historic properties. Please see EPA’s general fact sheet for discussion of other studies done as part of this permit process.

The public will have the opportunity to see and comment on EPA’s draft permit before a final permit decision is made. Since less than 15% of the spent carbon coming into Evoqua is considered RCRA hazardous waste, Evoqua can still continue to operate and regenerate the 85% non-RCRA carbon even if US EPA denies their RCRA permit.

Overview of the NHPA Process

US EPA has conducted a NHPA Sec. 106 review of the proposed RCRA hazardous waste permit for Evoqua and made a final determination of No Historic Properties Affected. A report documenting the steps taken in making this finding has been sent to the Colorado River Indian Tribes, the Arizona State Historic Preservation Office, Evoqua Water Technologies, and the Town of Parker, which are consulting parties to the NHPA process.

As part of the NHPA review, EPA first designated an Area of Potential Effect (or “APE”), which signifies the area in which historic properties may be directly or indirectly affected. EPA designated the APE to be a one-mile-radius around the facility in a January 2007 public notice.

Search for Historic Properties

EPA has taken a number of steps to identify historic properties within the APE. First, with assistance from the CRIT Museum Director and Attorney General’s Office, EPA reviewed past records regarding the facility area. Neither a walkover of the site nor a records search of Museum’s files revealed any historic sites in the area.

EPA also reached out to the public via public notices regarding the NHPA process and public comment periods in 2006 and 2007. None of the comments received identified any specific historic properties within the APE. A search of the National Register of Historic Places database likewise found no such sites within the APE.

Two sites were identified as potential historic properties under NHPA. One was Parker Cemetery, which lies within the APE and is a location where Navajo Code Talkers are interred. In addition, addressing public concerns about the proximity of the facility to Black Peak, a sacred mountain approximately 3 miles away, EPA considered all areas within the APE from where Black Peak may be viewed or from where prayers might be directed to Black peak to be an area of traditional religious and cultural importance.


EPA identified potential effects of facility operations on historic properties, including visual and auditory impacts, and impacts stemming from the presence of chemicals in the facility’s emissions. However, the facility can continue operating whether or not a permit is issued. Since the permit decision will not significantly affect facility operations, EPA has determined that a permit decision relating to Evoqua’s management of RCRA Hazardous Waste will have no effect on historic properties.

For more information on the NHPA process please see the following NHPA fact sheet:


Evoqua Contact Information

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