ORIN successfully treated chlorinated solvent contaminated groundwater utilizing full-scale in-situ chemical oxidation at a manufacturing plant facility. Contaminant levels were reduced from 1,888 ug/L to non detect over a two-month period. ORIN’s approach saved the client approximately $920K over traditional remediation approaches.

Site Characteristics:

  • Site: Manufacturing plant near Dallas, TX.
  • Geology: Clay and weathered bedrock interface at 20-25’
  • Groundwater velocity: variable (10-3 to 10-5 cm/sec)
  • Contaminants:
    • 48 ug/L Tetrachloroethene
    • 140 ug/L Trichloroethene
    • 1,200 ug/L 1,1-Dichloroethene
    • 500 ug/L cis-1,2-Dichloroethene

Remediation Approach:

  • Treatment chemistry: Sodium permanganate (NaMnO4).
  • Treatment application: Chemical injections through a series of direct push points.
  • Dosage rate – An average concentration of 10% NaMnO4 solution was injected at a rate of 1.5 to 6 gallons per minute. A total of 11,820 gallons of treatment chemical was injected throughout the targeted plume area.

Chemistries used during injection

Permanganates have been shown to reduce levels of chlorinated solvents in bench level testing prior to field implementation. A benefit of a permanganate remediation approach is the complete reaction of the contaminant without the formation of intermediate compounds commonly found with biodegradation.

For example, the breakdown of PCE with sodium permanganate is as follows:

  • 4NaMnO4 + 3C2Cl4 + 4H2O → 6CO2 + 4MnO2 + 4Na+ + 12Cl- + 8H+

Summary of Ex-situ Implementation

The chemistry was designed for the oxidation of chlorinated solvents (PCE, TCE and degradation products) in the groundwater at the site. Ninety-one injection points were completed throughout the impacted area. Seventy-one injection points were located outside the facility while twenty locations were utilized inside the building. Evidence of oxidant influence was observed during the injection by the increase of key groundwater parameters such as DO, ORP and conductivity in monitoring wells within the targeted plume area. Chemical influence was also observed in down and side gradient wells where color change was observed.

Effectiveness

Six months following the injection, monitoring wells were purged and sampled for VOC constituents. Average CVOC concentrations were reduced from 1,888 ug/L to non detect within the targeted plume area. Down gradient wells outside of active injection area also showed a significant reduction.

The Bottom Line

ORIN successfully reduced contaminant levels below target goals by injecting permanganate chemistry through a series of direct push injections over a six-day period. ORIN’s approach reduced full-scale costs by $920K and shortened project timeframe by years over traditional remediation designs.