US ARMY PUEBLO CHEMICAL DEPOT: PUEBLO, CO

Project Name:

Pilot Project at the US Army's Pueblo Chemical Depot in Pueblo, CO Installed with teaming partner ESN Rocky Mountain
System Type:

Anaerobic in situ Bioreactive System to Degrade Chlorinated Solvents
Client:

Versar, Inc./DOD
X-PeRT™ Design:

Biostimulation of identified indigenous degrading microbes.

Project Description:

Three hydrofracture well nests (BioNets™) were installed in November, 2004, each with five individual hydrofractures (BioLuxes™). The average diameter of each BioLux is about 35 feet (average thickness about ½ inch) and the five BioLuxes within each of the BioNets were stacked or spaced about 3-5 feet apart between about 38 and 55 feet below ground surface. Included in the fracturing slurry mix was Isolite®, small porous ceramic pellets made from diatomaceous earth, saturated with a proprietary liquid nutrient formulation specifically designed to biostimulate the natural occurring microbes identified as degraders of the contaminants of concern (PCE, TCE, DCE, and VC). Isolite® serves as a slow release carrier of the nutrients; as a proppant to hold the fractures open; and as a matrix (home) for the indigenous microbes to flourish.
Ground water samples were obtained in January from four monitoring wells and from five of the BioLuxes themselves. The results from three of the monitoring wells, as compared to base data collected in September, 2004, revealed that bioremediation activity had been enhanced with reductions in the concentrations of PCE and TCE from their base levels. These signs of degradation of PCE and its daughter products indicated that the BioLuxing procedure is appropriate and effective in reducing ground water contamination as designed. After analyzing the sampling data collected in January, 2005, a slightly modified nutrient formulation was injected in March to “recharge” the BioNets to further enhance the in situ biodegradation.

A second round of sampling was conducted in March and a third round in May, both of which confirmed that biodegradation of TCE, the targeted contaminant of concern, was being enhanced, especially within the treatment area. Between January and May, TCE had been reduced in BioNet 1 from 162 parts per billion (ppb) to 28.1 or 82.7%; BioNet 2 went from 523 to 0.25 ppb, or 99.1%; and BioNet 3 was reduced from 100 to 0.25, or 97.5%. The data collected in the BioNets and monitoring wells reflect that PCE is being rapidly reduced and its daughter products are going through the expected and desired transitory phases to support that biodegradation is being enhanced and working quickly and effectively at this pilot site.

The firm fixed price for installment and six months of O&M project was $145,795.