Case Study: Industrial Site, Houston, Texas

Site Summary
CL-Out® bioaugmentation was implemented in combination with dual phase extraction at an industrial site near Houston, Texas to remove trichloroethylene (TCE) from ground water. The overlying contaminated soil was excavated, but perched ground water and a deeper aquifer had TCE concentrations greater than 10,000 µg/L. A dual-phase vacuum extraction system was installed to control the ground water gradient and increase distribution of the CL-Out® organisms in the aquifer. The TCE concentrations were reduced by 99.9% in one year.

Geology and Hydrogeology
The site is located on coastal plain sediments characteristically interbedded sands, silts and clays. The first impacted ground water was a thin perched layer 16 to 18 feet below ground surface. A more transmissive, water bearing zone was at 25 to 30 feet deep. Both water-bearing layers and the interbedded fine-grained layers had TCE concentrations above regulatory standards.

Contamination
High concentrations of TCE were present in perched and deeper ground water. Prior to treatment, a small area of soil less than 500 square feet had TCE concentrations greater than 20,000 µg/L. The underlying impacted perched ground water area was the same size and had TCE concentrations up to 30,000 µg/L. The TCE migrated laterally in the underlying deeper ground water where the TCE concentrations were greater than 10,000 µg/L. The area of the deeper ground water plume was approximately 30,000 square feet.

Remediation
The contaminated unsaturated soil was excavated for treatment to the perched ground water. The perched ground water was treated by a combination of potassium permanganate and vapor extraction. The deeper aquifer was treated by a combination of dual-phase extraction and CL-Out® bioremediation.

CL-Out® was applied eight times between January, 2010 and February, 2011. During each application 55 to 110 gallons of CL-Out® was injected into the ground water. The dual-phase extraction system was used to control the ground water gradient and induce greater distribution of the CL-Out® microbes. Periodic plate count analysis of the microbial population in the treated aquifer was completed to guide where and when the CL-Out® population should be supplemented. The repeat applications were on approximately 4 to 6 week intervals.

Results
Following one year of bioaugmentation, the contaminant concentrations were reduced by more than 99%. The daughter products caused by incomplete natural breakdown were removed as well as the TCE. The following table shows the contaminant concentration trends in the treatment area.

Petrox microbes were added to excavated petroleum-contaminated soil to accelerate the degradation of DRO and ERO total petroleum hydrocarbons. Petrox was added by spraying the surface of the soil with a hydrated Petrox solution.  The microbes were mixed into the soil using a tractor-mounted disc tiller.                

After approximately 60 days, soil samples were taken for testing.  The soils showed 90% to 99% petroleum removal.  The following chart shows the range of DRO and ERO concentrations before and after Petrox treatment.

Petrox microbes provide quick response surface oil spill bioremediation.  Petrox can be applied to the oil surface with a backpack sprayer to initiate rapid bioremediation.  This approach protects surface water and vegetation with minimal surface traffic.

In the following example, an oil spill affected the vegetation and surface water at the edge of a lake. Contractors applied Petrox to the oil surface on vegetation and soil.  Periodic soil samples tracked the results.  After 90 days, the maximum and average concentrations decreased by more than 95% at a very low cost.