WARNING! conservative screening levels for over 100 chemicals found at sites with contaminated soil and groundwater. Mitigation Measures: The Supplemental VI Guidance references the DTSC (2011) Vapor Intrusion Mitigation Advisory (VIMA) for agency recommendations for mitigation measures. Multiple conservative assumptions were made when developing these Soil Screening Levels. •3©Ì¹]:´Ë�ŠÎİCS^"å‹9Y†}ª:Wİε1‘�¹æ©31ı‹Ü¢ô§ÜóÓœ*"Ñ
�–3}m�.äòà°ÁEËÃ(³œ3y€‡ef÷MkãÍ(uÆVQN°¾ìl¹.ÃÓ–õ^b”Òzy'βŠn¶{Ö–‚¨ƒ{œ[¿¶/H\³xøÀ™¥×Ù8A_wÈV™WÉà´Ç�ş°ñã\G&ó-. Soil Screening DQOs for Subsurface Soils .....4-28 Table 4.9. From Table 4-1, the soil scr-eening level for TPH (C4-CI2) is 500 mglkg at 20 to 30 feet above the groundwater table. Use of the more conservative AFs is likely to significantly increase the number of sites at which VI investigation, remediation and mitigation are required.Comparisons of the previous and new soil vapor screening levels for residential and commercial land use scenarios are shown below: 100 Foot Inclusion Zone: The Supplemental VI guidance requires soil vapor sampling within 100 feet of a VOC source area and source delineation in all directions, including off-site properties. The guidance, titled “Interim Supplemental Guidance: Screening and Evaluating Vapor Intrusion” (Supplemental VI Guidance), will have significant implications for property owners, developers, responsible parties, and attorneys with VI sites throughout California. Application of this Soil Screening Level is explained in “Use of California Human Note: Corresponding changes have been made to groundwater and soil ESLs. c or ca: Cancer is driving … » Alameda County Bar Association, What you need to know about the new rule of Professional Conduct on technology, News From the Court – Week of April 5 – April 9, 2021. Check out our membership page here, and our Environmental Law Section page here. IMPLICATION 2 – MORE ACTIVE REMEDIATION AND MITIGATION WILL BE REQUIRED: Active Remediation: The Supplemental VI Guidance explicitly states a preference for active remediation that removes or destroys VOCs, rather than reliance on mitigation measures. Interim Framework for Assessment of Vapor Intrusion at TCE-Contaminated Sites in the San Francisco Bay Region. It is recommended that you contact the DTSC site toxicologist to ensure appropriate use of air screening levels on a … As presented by the agencies issuing the guidance, the primary objective of the Supplemental VI Guidance is to better protect current and future building occupants from exposure to volatile organic chemicals (VOCs)[1] migrating from the environment to indoor air of buildings. The Department of Toxic Substances Control (DTSC) Human and Ecological Risk Office (HERO) released an update to its Human Health Risk Assessment Note (referred to as HERO Note 3 and available here) this week but did not provide more clarity on which soil vapor intrusion screening levels should be used to evaluate redevelopment of brownfield sites in California. Guidance for Developing Ecological Soil Screening Levels (Eco-SSLs) Chapter 4 of the guidance document was revised to reflect the changes to Attachment 4-1. The Supplemental VI Guidance also includes a general framework for making risk management decisions and selecting actions for addressing current and future VI risk. This change means that many sites at which VI was not a concern will now require sampling and evaluation, and potentially remediation or mitigation, to address VI concerns. California Human Health Screening Levels (CHHSLs) are concentrations of chemicals in soil or soil gas below thresholds of concern for risk to human health—that is, an excess lifetime cancer risk of one-in-a-million (10-6) and a hazard quotient of 1 for non-cancer health effects. Some agencies have already implemented elements of the guidance and are likely to continue to do so during the public comment period. In addition, current regulations provide only limited options through which a party can post financial assurances, further complicating site closure and transfer of properties with VI concerns. This is a significant change from past practices which allowed for the modeling of indoor air concentrations from existing soil vapor data when evaluating existing buildings. 2011. In this newsletter, we discuss the potentially significant implications of the Supplemental VI Guidance to the thousands, perhaps tens of thousands, of relevant sites across California. It is also likely to increase the potential for legal claims related to off-site conditions. The difference between the previous and new soil vapor ESLs are shown in Tables 1 and 2 below. The term AF, defined as the ratio of indoor air concentration to subsurface concentration, is used as a measure of the decrease in concentration that occurs during vapor migration from the subsurface to indoor air. All soil vapor samples must be collected from at least two depths at each location and sampling must be repeated at least twice (in different seasons) to assess spatial and temporal variability. The guidance incorporates technical information from recent research regarding VI and addresses previous inconsistencies in methodologies between various state agencies and the U.S. Environmental Protection Agency (U.S. EPA). Look for an ACBA announcement of a VI presentation in the coming months. For a number of chemicals, including tetrachloroethene (PCE) and trichloroethene (TCE), the new groundwater VI ESLs are more stringent (lower than) the maximum contaminant levels (MCLs) normally applied to drinking water.Use of the AF recommended in the Supplemental VI Guidance will ensure that consistent screening levels are applied across agencies and sites within the State: however, use of a single AF for each media does not support consideration of site-specific conditions, building construction or climatic conditions unique to California. January. Block, Esq. Indoor Air Sampling: Increased emphasis on indoor air sampling is anticipated under the Supplemental VI Guidance. In addition to Region 9 PRG values, the PRG Table also includes California EPA PRGs ("CAL-Modified PRGs") for specific chemicals where CAL-EPA screening values may deviate significantly from the federal values (see Section 2.4) and EPA OSWER soil screening levels (SSLs) for protection of groundwater (see Section 2.5). Measure and record foundation, structures, debris, utility infrastructure, and property-specific hazards. On September 8, 2016, California’s Office of Environmental Health Hazard Assessment (OEHHA) adopted an updated inhalation {Cancer} unit risk (IUR) factor for tetrachloroethylene (PCE). The Supplemental VI Guidance is not intended to be a comprehensive, stand-alone guidance on investigation, remediation, or mitigation of VI and does not specify cleanup goals, remedial strategies, or closure criteria; however, as discussed below, the guidance is likely to have substantial impacts on all of these issues.It is expected that, once the Supplemental VI Guidance is finalized, environmental regulatory agencies throughout California will apply the guidance in their assessment and management of properties with potential for VI.