ORIN successfully treated petroleum contaminated groundwater with enhanced bioremediation chemistry. Saturated contaminant levels were reduced from approximately 20 ug/L to less than laboratory detection limits. ORIN’s approach effectively remediated residual contamination that the onsite pump-and-treat system was unable to remove.

Site Characteristics

  • Site – Farm near Escanaba, Michigan
  • Geology – silty clay with shallow bedrock (4-8 ft bgs)
  • Contaminants – 11 ug/L benzene 4 ug/L ethylbenzene 4 ug/L xylenes

Remediation Approach

  • Treatment chemistry – ECH-O
  • Treatment application – In-situ chemical injections

Treatment Chemistry Description

EHC-O contains an oxygen releasing component that provides a long-term source of dissolved oxygen. Native microorganisms utilize the dissolved oxygen as an electron acceptor, and the targeted contaminant serves as the electron donor resulting in its destruction. The organic carbon component of this proprietary aerobic technology provides trace micronutrients required for healthy growth and proliferation of the indigenous, naturally occurring microbial population.

Summary of Remedial Implementation

Using Geoprobe direct push technology, 1 ¼-inch (in.) diameter steel rods with disposable tips were advanced to bedrock at 4- to 8-feet below ground surface (ft bgs) in order to facilitate chemical injection. Approximately 50 gallons of ECH-O treatment chemistry at 15% solution was injected into each of the eighteen injection points. The injection points were located across the site to facilitate the most complete lateral coverage coupled with the existing operational pump-and-treat system. Exact injection point location and volume of injected solution varied depending on unforeseen site conditions and soil matrix properties.

Effectiveness

Approximately one year after the injection (two sampling events) both wells that previously contained BTEX compounds were sampled and all VOCs analyzed were below detection limits. The EHC-O was able to remediate the remaining recalcitrant compounds subsequent to the onsite pump-and-treat system being deemed ineffective for further remediation due to the soil type and length of operation.

The Bottom Line ORIN successfully remediated the site by injecting ECH-O treatment chemistry slurry through a series of direct push points over a one-day period. Compared to alternative cleanup approaches already being implemented but deemed ineffective, using chemical injection proved less expensive, more effective, and less disruptive. The site is currently under review for closure.