Industrial Petroleum Soil Bioremediation: 97% TPH Reduction with On-Site Windrow Treatment

Results at a glance

Metric	Before	After
Soil TPH (C10-C40)	~20,000 ppm	650 ppm (97% lower)
Oil and grease	1,100 mg/kg	45 mg/kg (96% lower)
Porewater sulfate	Elevated	~50% lower
Staining and odor	Heavy	Eliminated, greatly reduced
Disposal method	Off-site hauling	On-site windrow, soil returned

The problem

An industrial site exhibited severe soil contamination from long-term petroleum exposure, with total petroleum hydrocarbons (C10–C40) measured at approximately 20,000 ppm, oil and grease concentrations near 1,100 mg/kg, and elevated sulfate levels in the soil porewater. The site showed visible petroleum staining, strong hydrocarbon odors, and regulatory non-compliance that required active remediation rather than natural attenuation. The owner needed a cost-effective on-site bioremediation approach that could remove the hydrocarbon load without excavating and trucking soil to off-site disposal. The project evaluated whether Petroleum Treat (PT), a high-CFU petroleum hydrocarbon degrading bacteria blend, could deliver effective biological treatment in a controlled windrow program where contaminated soil was treated on site and returned to its original condition after remediation.

Before, during, and after

Before
Before treatment, the soil showed heavy petroleum staining, persistent hydrocarbon odors, and depressed biological activity, indicating that natural attenuation alone was insufficient to reduce petroleum hydrocarbons to acceptable regulatory levels without active intervention. Baseline analysis confirmed total petroleum hydrocarbons (C10–C40) at approximately 20,000 ppm, oil and grease concentrations near 1,100 mg/kg, and elevated sulfate in soil porewater, all consistent with long-term petroleum exposure and limited microbial capacity to degrade the hydrocarbon load on the existing site biology.

After
Petroleum Treat (PT) was applied as a high-CFU petroleum hydrocarbon degrading bacteria blend within a controlled on-site bioremediation program. Contaminated soil was placed into windrows, biologically treated with PT, and returned to its original location after remediation, eliminating the cost and disposal burden of off-site hauling. Post-treatment analysis showed total petroleum hydrocarbons (C10–C40) reduced from approximately 20,000 ppm to 650 ppm, a 97% reduction, oil and grease reduced from 1,100 mg/kg to 45 mg/kg, a 96% reduction, and sulfate levels in soil porewater reduced by approximately 50%. Visible petroleum staining was eliminated and hydrocarbon odors were substantially reduced. For environmental remediation contractors, industrial site owners, and regulatory project managers handling petroleum-contaminated soil, this case demonstrates what windrow-based petroleum bioremediation with high-CFU hydrocarbon degrading bacteria can deliver on real-world contaminated sites.

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Product used in this trial

Petroleum Treat (PT)

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