Soil and groundwater clean-ups in California have typically allowed an elevated level of constitutents to remain in the soil and groundwater despite issuance of No Further Action letters (NFAL)by regulatory authorities. Companies recognized some level of risk associated with NFALs due to the open-ended wording of the documents that allowed the authorities to reopen the clean-up under certain circumstances like reduced clean-up levels or identification of other constitutents of concern. The level of risk did not include risks associated with soil vapor intrusion until recently, within the last 3-5 years depending on the regulatory authority. Soil vapor intrusion has become an issue for brownsfield development generally, although residential redevelopment is most at risk. Local and regional authorities in California have taken a piecemeal approach to the complications of soil vapor intrusion at remediated sites, relying on the reopener clauses of the NFALs to request investigation and remediation. In October 2007, the Legislature enacted