Certain VIAP investigations will indicate that a remedial action [see Sec. 20101(1)(qq)] is necessary to reduce indoor air concentrations to acceptable levels, or that a vapor source can be easily treated or removed. In some instances, environmental technologies designed for source remediation can also serve as VIAP mitigation strategy. Land or resource use restrictions (see Section 5), when implemented, can provide an administrative assurance for mitigating a known or potential VIAP concern, or address future uses.
Environmental remediation focuses on reducing source area concentrations of volatile hazardous substances to below site-specific criteria; however, it can also serve as a mitigation strategy. Common remediation technologies that can also serve as a mitigation strategy include soil vapor extraction (SVE) and multiphase extraction (MPE). Remediation performance metrics and site closure are based on achieving soil and groundwater or soil gas cleanup goals. Soil gas sampling can be used to show compliance with soil and groundwater criteria. Below is a list of remediation technologies and their associated ITRC Information Sheet (2020):
- Soil vapor extraction (SVE, see also Soil vapor extraction (SVE) Technology Information Sheet)
- Multiphase extraction (MPE; see also Multiphase extraction (MPE) Technology Information Sheet)
- Institutional controls (ICs; see also Institutional controls (ICs) Technology Information Sheet)
The other remedial action that can be implemented when the site conditions warrant is source removal via excavation. Though not detailed in ITRC or this document, the principles of source removal and excavation are commonly implemented; and therefore, no further information is provided within this volume. When the source is removed, it will drastically reduce the VIAP investigation and evaluation needed.