TranslateGainesville Creosote Site
A 90-acre site with extensive creosote contamination. Pump & treat system was in place. IET conducted multiple pilot tests and full-scale treatments from 2008 to 2018, including:
- SA pilot (Source Area) - 2008
- UHG pilot (Under-building Horizontal Grouting) - 2014
- ISGS pilot (In Situ Geochemical Stabilization) - 2015
- Full-Scale treatment - 2015
- South Lagoon treatment - 2018
Multiple former process areas, north lagoon, and south lagoon were addressed across the 90-acre site.
Scale of Operations:
- 267 Direct-Push Injection Points
- 1,500 Discrete Depths
- 187,000 Gallons of Reagent Injected
ISGS technology focuses on NAPL encapsulation rather than just chemical oxidation, using modified permanganate solutions to physically coat NAPL and reduce contaminant flux while destroying dissolved-phase contaminants.
DNAPL Recovery Results:
- Well DNAPL Reduction: 83%
- Piezometer DNAPL Reduction: 83%
- Pre-ISGS Average Recovery: 30.4 gal/2-weeks
- Post-ISGS Average Recovery: 3.5 gal/2-weeks
Costs include characterization, pilot test and full-scale treatment
This Gainesville project demonstrates one of the largest-scale ISGS (In Situ Geochemical Stabilization) deployments in IET's portfolio — 267 direct-push injection points, 1,500 discrete injection depths, and 187,000 gallons of reagent delivered over a multi-year phased program. ISGS uses a modified permanganate-based amendment to chemically oxidize and polymerize NAPL (non-aqueous phase liquid) in place, physically coating NAPL globules with manganese oxide precipitate and dramatically reducing contaminant flux to groundwater.
The scale of this program — 267 injection points across the site — reflects the large footprint of the creosote/coal tar NAPL source zone, typical of former wood treatment or MGP sites in Florida. Each injection point was treated at multiple discrete depth intervals (1,500 total depths across 267 points = an average of 5.6 depth intervals per point), ensuring vertical coverage of the NAPL zone from 5 to 67 feet below ground surface. The 187,000 gallons of reagent delivered provided the amendment mass needed to achieve the 83% DNAPL reduction documented in the treatment results.
The targeted approach — treating only the DNAPL-impacted portions of the site rather than the entire 5–67 foot column — generated $8.0M in cost savings compared to full-footprint treatment ($2.5M actual vs. $10.5M full-footprint estimate). This targeted ISGS strategy demonstrates the economic advantage of precise source zone characterization followed by focused amendment delivery, rather than the blanket treatment approach that characterizes less technically sophisticated remediation programs.
Gainesville, Florida is located in Alachua County within the Northern Highlands physiographic province of the Florida peninsula. The shallow geology consists of Tertiary-age limestone and sand deposits of the Floridan Aquifer System — one of the world's most productive groundwater systems. Creosote and coal tar NAPL contamination at this site likely originated from historical wood treatment operations, which used creosote as a preservative for utility poles and railroad ties.
Creosote NAPL is particularly challenging to remediate because it is a complex mixture of hundreds of polycyclic aromatic hydrocarbons (PAHs) with high density, high viscosity, and very low aqueous solubility. The NAPL tends to pool at lithologic interfaces and in limestone solution features, creating persistent source zones that can sustain dissolved-phase plumes for decades. ISGS is ideally suited for this contaminant class because the permanganate-based amendment polymerizes the PAH compounds in place, physically stabilizing the NAPL mass rather than attempting to fully destroy it — an approach that is both more cost-effective and more reliable for large NAPL source zones than conventional ISCO or bioremediation alone.
