• Illinois Proposes Soil Vapor Intrusion Requirements
  • January 28, 2009 | Author: Mark J. Steger
  • Law Firm: Holland & Knight LLP - Chicago Office
  • On September 3, 2008, the Illinois Environmental Protection Agency filed proposed amendment to Illinois’ risk-based remediation standards to include the indoor inhalation exposure route. The indoor inhalation exposure route (commonly referred to as “vapor intrusion”) will be addressed in the same fashion as the existing exposure routes and include residential and industrial/commercial remediation objectives as well as pathway exclusion. The proposed rules will protect building occupants from volatile chemicals that have the potential to migrate from the soil and groundwater to indoor air.

    Extensive Evaluation of Indoor Inhalation

    Under the proposed rules, the indoor inhalation exposure route will be evaluated using soil and groundwater or soil gas sampling data and applying a modified Johnson & Ettinger model to develop remediation objectives. The modified J&E model simulates the migration of contaminants from the subsurface source to inside air. The proposal adds new definitions for building and building control technology as well as definitions for manmade pathways and volatile chemicals to address the indoor inhalation exposure route. The Illinois EPA proposed excluding the indoor inhalation exposure route if volatile chemicals or mercury are not present, existing or potential buildings or manmade pathways are not or will not be located over contaminated areas, an approved engineered barrier is in place, or an approved site-specific building control technology is in place and will be in place for future buildings prior to occupancy. Finally, the appropriate institutional controls must be placed on the property. A groundwater ordinance prohibiting use of groundwater as a drinking water source cannot be used to exclude this route.

    In the past, Illinois evaluated the indoor inhalation exposure route on a limited basis, addressing only major indoor inhalation risks. USEPA recommends screening all sites for indoor inhalation risks, and other states have addressed this exposure route. The proposed rules build on the guidance prepared by New Jersey, New York, Pennsylvania, Missouri and Colorado, among others, in developing the appropriate remediation objectives.

    The regulations, when finalized, will impact those sites undergoing remediation using Illinois’ risk-based methodology for determining remediation objectives and includes sites in the voluntary cleanup program, the underground storage tank program, RCRA and other Illinois remediation programs.

    Finally the Illinois EPA indicated that if a site has not obtained a “No Further Remediation” letter by the effective date of the final rule, then the indoor inhalation exposure route will need to be evaluated. However, the Illinois EPA has indicated that it will only reopen closed sites if information demonstrates a threat to building occupants.

    Hearings are being held on the proposed regulations, and it is anticipated that these amendments will be in effect in the spring of 2009.