In situ chemical oxidation using potassium permanganate was chosen as a demonstration technology to treat dense nonaqueous-phase liquid (DNAPL) trichloroethylene (TCE) at NASA’s Launch Complex 34 groundwater cleanup site. The site geology consists of several stratigraphic units containing layered, heterogeneous lithology with permeability contrasts of two orders of magnitude. TCE was present before treatment at up to 30,000 milligrams per kilogram in soil and 1,500 milligrams per liter in groundwater. Approximately 6,100 kilograms of TCE were estimated to lie within the 50- 75-foot demonstration plot. The permanganate injection strategy consisted of direct- push pressure injection (lance permeation). Over 150,000 pounds of permanganate were injected at 2-foot discrete intervals at numerous locations across the demonstration plot in a 3-phase injection program. The total reduction in TCE mass was calculated through collection and analysis of over 192 discrete soil samples. The results indicate an overall reduction of 75 percent using statistical Kreiging analyses.

The injection system was designed to deliver permanganate at precise dosages over 2-foot vertical intervals from the top of the contaminated zone to the base of the demonstration at 45 feet below grade. This design was chosen because the formation permeabilities and contaminant mass distribution varied both laterally and vertically. The permanganate dose and application rate and duration were adjusted at each point to provide the desired loading corresponding to the level of contaminant mass at that location and vertical interval. The demonstration plot was divided into three different lithologic units for treatment: an Upper Sand Unit (USU), a Middle Fine-Grained Unit (MFGU), and a Lower Sand Unit (LSU). The MFGU and LSU contained a high proportion of silt, clay, and shell lenses. Nineteen separate injection rods and injection tips were driven to the desired depths by a direct push rig.

The injection tip consisted of a customized Geoprobe open 9-interval, 360-degree circumference, hole-perforated drive stem located between 2 wider sections that functioned as packers. The perforated drive probe had 0.25-inch perforations and a 0.010-inch-slot continuous wire-wound stainless-steel screen.

The permanganate delivery system consisted of an onsite continuous-mix, automated-feed system developed by the permanganate supplier, Carus Chemical Company. Combining the dry, free-flowing potassium permanganate solid with hydrant water mixed the permanganate solution to an injection concentration range of 0.2 to 3.0 percent. The permanganate treatment was conducted in phases so that the interim results obtained could be used to focus subsequent injections.

Key accomplishments:

• April 2000: Field-scale deployment complete.
• June 2000: Postdemonstration data collection.
• 2001: 9-month postdemonstration data collection.

Key milestone:

• 2002: Data evaluation and comparison to other DNAPL cleanup technologies.

Contact: Dr. J.W. Quinn (Jacqueline.Quinn-1@ksc.nasa.gov), YA-C3-C, (321) 867-8410
Participating Organization: IT Corporation (W. Leonard and E. Mott-Smith)