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Success Stories - Siting Renewable Energy on Contaminated Land
Apache Powder Superfund Site, Rio Cochise County Arizona
Solar and Wind Energy Used to Power Cleanup of Contaminated Ground Water at Apache Powder
Site Description
The Apache Powder Superfund Site encompasses nine square miles
(approximately 1,100 acres of land) and is located seven miles
southeast of the incorporated town of Benson, Arizona, and 2.5 miles
southwest of the unincorporated town of St. David, Arizona. The San
Pedro River bounds the eastern side of the site, running from the
southeast corner of the property north towards the northwest.
Property History
Apache Powder (now Apache Nitrogen Products, Inc. or ANP) began
manufacturing dynamite in 1922 for mining and construction projects
throughout the southwest. Later, ANP broadened its product line to
include ammonium nitrate, nitrogen-based fertilizer products, blasting
agents, and nitric acid. Today, ANP manufactures various forms of
ammonium nitrate and nitric acid.
In August 1990, EPA placed the site on the National Priorities List of
Superfund sites because of groundwater and soil contamination. During
the intervening years, ANP has cleaned up the soil contaminated with
lead, dinitrotoluene (DNT) and trinitrotoluene (TNT) by a combination
of onsite treatment and off-site removal and disposal. The remaining
soil and sediment contaminated with heavy metals in the onsite ponds
have been capped with native soil materials.
In September 2008, EPA signed a Preliminary Closeout Report stating
that all construction activities related to site cleanup are complete.
Currently, the only cleanup requirements remaining are for long-term
cleanup and monitoring of ground water. ANP is monitoring the
southern area ground water until the cleanup standards for nitrate and
perchlorate (the primary contaminants) are met. For the northern area
ground water, ANP is treating the nitrate-contaminated ground water in
constructed wetlands.
Renewable Energy Development
Different forms of renewable energy are being used to help clean up the
ground water in both the northern and southern areas. Wetlands are the
ultimate source of renewable energy, in that the sun provides the
necessary energy for the plant material and the microorganisms in the
root systems that remove (denitrify) the nitrate. ANP also is using solar
photovoltaics and wind to enhance the cleanup operations.
In 1997, ANP constructed the 4.5-acre tiered hydraulically driven
wetland system on the northern portion of the site. It treats
approximately 150 gallons per minute (80 million gallons/year) of
contaminated water. For the first five years of start-up, a 1.4 kW PV
panel provided solar power for a centrifugal pump to recirculate (at 5
gallons/minute) the contaminated water through the wetlands cells until
the treated water reached the discharge cleanup standards. Now that the
wetlands are removing the nitrate to well below the drinking water
standard for nitrate, the PV system is no longer needed. However, a
mini-solar PV panel is used on the flow meter to measure the volume of
water moving through the wetlands system. In the southern area, a
windmill is pumping water to de-water a perched system underlying the
formerly-used evaporation ponds that now are capped.
Key Partners:
Current Status:
EPA Region 9, Rio Cochise County, AZ
1,100 acres
Private - Apache Nitrogen Products,
Inc., formerly Apache Powder
Chemicals and explosives
manufacturing
Nitrate and Perchlorate
Superfund
Solar; Wind
Estimated at $2.5 million - includes
construction and performance
monitoring and O&M costs (to date) for
northern area wetlands system,
including solar PV pumping systems
and field equipment, and windmill for
southern area perched system (cost
does not include soil cleanup)
ANP; EPA Region 9; Arizona
Department of Environmental Quality
Construction Complete (for site
cleanup) issued September 2008;
long-term monitoring ongoing
PROJECT HIGHLIGHTS:
Use of renewable energy sources .including constructed
wetlands, solar PV, and wind energy, for cleanup of
ground water contamination reduced the 1994 original
30-year ground water cleanup cost estimate from $25
million to $10 million or less, due to significantly lower
annual operation and maintenance and energy costs.
Cost of solar PV system for circulating water in the
northern wetlands and the windmill pump for the
southern perched system was 3 times less expensive
than the cost to run power lines and pay for electricity to
these remote areas.
To date, constructed wetland system has treated over
408 million gallons of ground water and removed over
497,000 pounds of nitrate-nitrogen.
CONTACT: Arizona Department of Environment Quality: Bill Ellett, Project Manager: 1-888-271-9302, ellett.william@azdeq.gov
EPA Region 9 Project Manager, Andria Benner, 415-972-3189, benner.andria@epa.gov
To learn more about siting renewable energy on contaminated land, visit: www.epa.gov/renewableenergyland
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