Coastal Florida

1,4-Dioxane in Fractured Bedrock

Managing Phytotoxic Concentrations

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Underlying Clean Groundwater Zone

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Managing Phytotoxic Concentrations --- Underlying Clean Groundwater Zone ---

Objective:
Evaluate the efficacy of a TreeWell® system as a sustainable and cost-effective replacement for a costly and ineffective pump-and-treat system.

Site Conditions:
The source area remained active, and a plume of 1,4-dioxane was migrating offsite through a fractured bedrock aquifer. Shallow aquifer media (0–2 meters) consisted of clean, sandy soils, while the deeper zone (2–4.5 meters) contained contaminated groundwater within fractured bedrock.

Implementation:
To facilitate the installation of a targeted remediation system, a mature vegetative canopy was removed. A 154-unit TreeWell® system was subsequently installed to address groundwater contamination within fractured bedrock. The design focused on intercepting and treating a plume of 1,4-dioxane migrating offsite.

The system incorporated some native wetland tree species selected for their tolerance to site conditions and phytoremediation potential: Slash Pine (Pinus elliottii), Willow (Salix spp.), Sycamore (Platanus occidentalis), Cypress (Taxodium distichum), and Laurel Oak (Quercus laurifolia).

Results:

  • Eliminated high-cost pump-and-treat system, saving the client approximately $300,000 per year in operational costs.

  • Replaced ineffective UV/peroxide treatment with a TreeWell® System, delivering measurable contaminant reduction.

  • Achieved active remediation and hydraulic control of the impacted zone beneath clean groundwater, with low O&M requirements.

  • Secured regulatory closure in record time:

    • No Further Action granted within three years.

    • Site Rehabilitation Completion Order (SRCO) issued by the Florida Department of Environmental Protection.

  • Resolved a 20-year remediation challenge through nature-based, cost-effective intervention.