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Bioremediation is a viable mechanism for treating soils contaminated with petroleum hydrocarbons. Bioremediation strategies range from encouraging natural biodegradation processes (biostimulation) to supplementing the existing system with microorganisms able to degrade the contamination (bioaugmentation) and to monitoring and verifying natural processes (natural attenuation). Application of bioremediation technologies is customized to specific site characteristics, as contaminated soils may be excavated for on- or off-site treatment at surface (ex situ) or treated in place (in situ). In situ technologies, such as bioventing, are often cost-effective, but delivery and mixing of stimulants with the microorganisms and contaminants are challenging. Ex situ technologies, namely, landfarming and biopiles, provide greater process control but also increase costs, disruption, and exposure to contaminants. Microorganisms capable of degrading petroleum hydrocarbons have been found to be prolific in the subsurface. Alteration of environmental conditions is often paramount to enabling biodegradation; temperature, pH, salinity, nutrients, moisture, and redox condition may be altered to enhance or accelerate treatment. Biosurfactants also provide an additional means of improving treatment by increasing the surface area of hydrophobic hydrocarbon compounds, thus increasing exposure to microorganisms. Bioremediation of soil contaminated with petroleum hydrocarbons provides a flexible, cost-effective, environmentally sustainable treatment strategy that is tailored to site-specific conditions and requirements.