Hart & Hickman conducted vapor intrusion evaluation and mitigation activities at a Brownfields site that was converted for use as a multi-tenant office and warehouse building. The site was formerly used for the manufacture of textile chemicals and high concentrations of chlorinated volatile organic compounds were present in groundwater from historical activities including former solvent underground storage tanks. H&H conducted several rounds of indoor sampling and performed a cumulative risk evaluation to demonstrate that only one of the building units contained compound concentrations above commercial/industrial risk levels. Based upon the indoor air sampling, H&H developed a vapor mitigation system design using subslab depressurization which was approved by State regulators. As part of the system design process, H&H performed a 25-point field subslab soil vapor survey using a field organic vapor instrument to determine the source of the compounds so that the mitigation system could most effectively control vapors in the source area and the size of the system could be reduced. H&H subsequently completed subslab depressurization system installation and follow up sampling to demonstrate the effectiveness of the system.