Free Product, BTEX and Polycyclic Aromatic Hydrocarbons (PAHs) Remediation
Former Retail Gas Station in Florida
Several circumstances converged to elevate this site to the special category status. A magnificent Antebellum Home dominated the landscape just a few yards from the site of a former 1920s era service station. The beautiful shrubbery and wall belied the environmental nightmare lurking below. Fuel releases from the stations inception until it was removed in 1979, had accumulated as free product impacting both soil and groundwater. Conventional remedial options (systems, excavation, etc.) were judged inappropriate because of the fear of damage to this National Historical Landmark. A search of proven technologies found that the Cool-Ox® in-situ chemical oxidation (ISCO) Process offered the highest probability of remediation with the lowest risk of damage to the site.
PROJECT AT A GLANCE
Type of Site: Former Retail Gasoline Station
Location: Madison County, Florida
Contaminants: Free Product - BTEX/PAHs
Work Scope: Inject Cool-Ox® Reagent
Media Treated: Soil & Groundwater
Soil Type: Sandy Clay to Hard Clay
Groundwater Depth: 40 fbgs
Remedial Objectives (Phase 1):
Eliminate Free Product & Initiate Groundwater Remediation
Application Method: DPT Probe Rig
Area Treated: 5,000 square Feet
Vertical Interval: 25 to 50 feet bgs
Injection Point (IP) Spacing: Irregular
Media Volume Treated: 1,186 cubic yards
Number of Injection Points: 39
Cool-Ox® Volume: 6,944 gallons
Cool-Ox® per IP: ~178 gal
The blue area on Map 1 depicts the extent of the groundwater contaminant plume prior to the first Cool-Ox® injection. Samples collected after the Phase 1 injection, revealed that the free product had been eliminated (see red area – Map 1) and that the groundwater plume had enjoyed a significant reduction in both size and contaminant concentrations (see blue and green areas – Map 2).
Prior to treatment, free product and high levels of petroleum contaminants in the GW were located below the shrubbery on site and along US Highway 90. Following the Cool-Ox® injections, BTEX concentrations in groundwater were reduced by more than ~95%.
Phase 1 was successfully completed with the elimination of free product and “zero” damage to the Home or grounds. The property was put into the Florida monitored natural attenuation (MNA) program because of the spectacular results after the first application. Three years after our application,the site met all closure standards and thus, received closure documentation. No additional applications were necessary.
Results of the Phase 1 Cool-Ox® injection revealed that application was cost effective and safe at this historic site. Site limitations allowed a relatively modest volume of reagent to be injected. Soil and groundwater contaminants extended beneath US Highway 90 and free product had been detected where the former gas station had stood. Post application results qualified the site for the Florida Monitored Natural Attenuation (MNA) program. Three years later the site met all qualifications for closure.