4.1 Intended Application of Guide—This guide is intended for use at properties that are presently developed or proposed for development for residential, commercial, or industrial purposes but which contain chemical-affected soil, groundwater, air, or other environmental media, which may pose an unacceptable risk to human health. This guide can be used as a tool for planning and implementation of property reuse or redevelopment activities at former commercial/industrial facilities, “brownfield” properties, or properties containing naturally occurring, chemical-affected environmental media so as to effectively manage potential human exposures to COCs which might otherwise limit productive use of the property.
4.2 Situations Where This Guide May Be Applied—An engineering control may be needed as part of the development plan when: (1) COCs are present in soil, groundwater, or other environmental media at concentrations posing unacceptable risk(s) to human health per applicable regulatory criteria or a risk-based evaluation; (2) a potentially complete exposure pathway for COCs is likely to exist in the absence of an engineering control or other response measure, and (3) installation and maintenance of the engineering control is determined to be an applicable and cost-effective response action relative to other options. A property should not be excluded from development or redevelopment solely on the basis of chemical-affected media, in general, and chemical-affected groundwater, in particular. If no affected environmental media are identified as having COC concentrations in excess of applicable regulatory standards or risk-based criteria, then engineering controls or other response measures are not required.
4.3 Assumptions for Use of This Guide—For use of this guide, it is assumed that (1) an environmental site assessment has been completed to characterize chemical-affected environmental media, (2) exposures to COCs posing an unacceptable risk to the health of current or future property users have been identified based upon a risk-based corrective action analysis or other evaluation consistent with applicable regulatory requirements, and (3) engineering controls are being considered as a potentially effective and acceptable measure to manage exposures to chemical-affected environmental media remaining in place at the property. This guide assumes that the property is served by a public water supply or other water source so that use of on-site groundwater or surface water resources as a water supply is not necessary.
4.4 Presumptive Use of Engineering Controls—The design basis for any engineering controls installed depends on the risk to be controlled, nevertheless, if no known risk has been identified, the guide may be implemented at the discretion of the site developer. As a conservative measure to reduce or eliminate potential unidentifi......