A Tale of Too Many Nitrates: The Palette of a 20-Year Superfund Study

Tuesday, April 21, 2009: 1:50 p.m.
Agave Ballroom (Hilton Tucson El Conquistador Golf & Tennis Resort )
Leo S. Leonhart, Ph.D., RG , Hargis + Associates Inc., Tucson, AZ
Beth Ann Scully , Hargis + Associates Inc., Tucson, AZ
Amy L. Milsom , Hargis + Associates Inc., Tucson, AZ
Eric M. Roudebush, PE , Hargis + Associates Inc., Tucson, AZ
Manufacturing of commercial nitrogen products at the Apache Nitrogen Products, Inc. (formerly Apache Powder Company) site in Cochise County, Arizona have been ongoing continuously since 1922.  As a result of historical industrial wastewater practices, dissolved nitrate has been found in shallow ground water along the San Pedro River and downgradient from the manufacturing areas.  At one time, it was determined that the ground water nitrate-N plume extended nearly three miles. In the Fall of 2008, the U.S. Environmental Protection Agency made a determination of “construction complete” with regard to the required remedial actions at the site.  This action came after about twenty years of CERCLA investigations, with prior regulatory involvement at the State level dating back even earlier.  Owing to this lengthy history of remedial investigations, a number of the topics highlighted for this NGWA session on Nitrates in Ground Water is available for discussion.  Included among those topics are:  occurrence of nitrates in domestic wells; fingerprinting nitrate/forensics to distinguish various sources; assessment of long-term trends in ground water nitrate; denitrification processes; quantification/ assessment/mapping of denitrification zones in aquifers; nitrate and co-contamination with salts; regulatory control of nitrate in ground water; remediation of nitrate in ground water; and computer modeling of transport and fate/geochemistry of nitrogen at various scales.  Each topic will be presented along with examples and the respective findings of interest. 
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