Strong housing demand and a limited supply of urban land in Florida has increased the residential development of former agricultural lands. At a former 14-acre ornamental nursery site, historical use of arsenical herbicides and pesticides contaminated soil and groundwater to levels exceeding residential cleanup goals. A site assessment identified the extent of soil and groundwater with arsenic concentrations greater than regulatory cleanup goals. Analysis of soil samples collected from more than 300 locations indicated that arsenic concentrations were above the residential soil cleanup goal (2.1 mg/kg), arsenic leached to the groundwater at concentrations above the groundwater cleanup goal (0.05 mg/l), and contaminated soil was non-hazardous based on TCLP tests. A leachability study established a site-specific leachability soil cleanup goal of 12 mg/kg. A soil management plan was prepared and implemented in 2006. During implantation of the soil management plan 43,000 tons of soil were excavated and disposed offsite as non-hazardous waste.

Arsenic concentrations in groundwater range up to 4 mg/l. Because of the quantity, oxidation state, and distribution of arsenic in groundwater above the groundwater cleanup goal, the most viable method for groundwater remediation was identified as groundwater extraction and treatment. To treat arsenic in extracted groundwater, several technologies were reviewed. An adsorption technique was selected based on bench and field-scale treatability studies. The primary component of the selected treatment technology is an adsorbent (granular ferric oxide) that has a high capacity for arsenic adsorption. Groundwater remediation began in December 2004 and stopped in October 2006 prior to implementation of the soil management plan. During this period, approximately 11 million gallons of groundwater were extracted and 55 pounds of arsenic removed from groundwater. In 2007, the groundwater remediation system (20 gpm) was reconstructed during site development activity. The expected duration of the project and cost is 5 years and $3,000,000.