An in situ soil remediation system may be used to remove or reduce levels of mercury contamination within soil. The soil remediation system may also remove or reduce levels of other contaminants within the soil. Mercury may be vaporized within the soil by a heating system. The vaporized mercury may be removed from the soil by a vacuum system. The vaporized mercury may pass through heated risers that elevate the vaporized mercury. After the vaporized mercury passes from the heated risers, the vaporized mercury may be allowed to cool, condense, and flow downward to a treatment facility. Removing mercury from the soil as a vapor may provide an economical, safe, and efficient way to remediate mercury contaminated soil.