The 120-acre municipal Harrison Road Landfill was operated by the City of Tucson from 1972 to 1997 (Harrison Landfill Site Map).

Volatile Organic Compounds (VOCs) were detected in nearby groundwater in 1994 and reported to the Arizona Department of Environmental Quality (ADEQ).  Environmental Services Engineering & Technical Support installed additional monitoring wells on State land in 1997 to define the downgradient edge of the plume. The highest levels of VOCs detected are Perchloroethylene (PCE) at 60 parts per billion (ppb) and Trichlorethylene (TCE) at 26 ppb.  The aquifer water quality standard for both PCE and TCE is 5 ppb.

Environmental Management is using a three-pronged attack (paid for by 1994 and 2000 bond funds) against the contaminant plume.  In order to eliminate the source of the plume, Environmental Services Engineering & Technical Support installed a deep soil vapor extraction system which started full-scale operation in August 1999.

Soil vapor extraction system at Harrison Landfill.

In order to contain the spread of the existing plume, Environmental Services Engineering & Technical Support implemented a pump-and-treat groundwater remediation system which began operation in June 2001.  And in order to eliminate the existing plume, nutrients (food-grade sodium benzoate) are being added to onsite wells to enhance the natural biological degradation processes. At one pilot well, these nutrient injections reduced the PCE concentration from 30 ppb to less than 5 ppb.

Using this three-pronged attack, Environmental Services Engineering & Technical Support projects that the contaminant plume will be completely contained within the Harrison Landfill by 2007.

In 2002, Environmental Services Engineering & Technical Support was recognized for this innovative and cost effective approach to groundwater clean up with both state and national awards from the American Public Works Association.