Reso PC17-07 0032 PC Reso Approving CEQA - 860 Charter St

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LSA ASSOCIATES, INC. SEPTEMBER 2016 ROCKETSHIP REDWOOD CITY ELEMENTARY SCHOOL PROJECT INITIAL STUDY/ MITIGATED NEGATIVE DECLARATION P:\RWC1401B Rocketship School\PRODUCTS\IS-MND\Public\Rocketship Public Review 09-29-16.docx (09/29/16) PUBLIC REVIEW DRAFT 55 The investigation indicated that vapor intrusion of VOCs may be a concern in the eastern and southwestern portions of the existing building but did not identify a source for these VOC vapors. The VOCs may be residual shallow contamination from historical use of cleaning solvents at the site, a conclusion supported by the presence of low-permeable clays in the subsurface, which would impede the vertical migration of VOCs from groundwater. Based on the findings from Cornerstone Earth Group’s 2014 investigation report, the SMCDEH opened an environmental oversight case for the project site under the voluntary cleanup program in accordance with California Health and Safety Code (CH &SC) Sections 101480 and 25260. However, the SMCDEH has notified the Regional Water Quality Control Board (Water Board) and the Department of Toxic Substance Control (DTSC) that the SMCDEH cannot oversee the case because the SMCDEH records do not contain evidence that the previous tenants of the property used or stored halogenated volatile organic compounds (HVOCs).67 As of April 2016, the DTSC is actively providing regulatory oversight for the property. Though written documentation of further investigation and remedial action is not yet available on the Geotracker or Envirostor databases, interviews with the DTSC case manager indicate that progress is being made to address the soil vapor issue.68 Specifically, the property owner’s consultant team has designed and installed soil vapor recovery systems designed to interrupt the potential exposure pathway of volatilization of contaminants to indoor air (i.e., a subsurface ventilation system that draws the vapors from under the building so that they cannot collect inside the building at unsafe levels). In a letter dated June 28, 2016, the DTSC staff approved a Work Plan to test the effectiveness of the system.69 The testing would include multiple rounds of collecting indoor air samples within the building and testing these samples for the appropriate VOCs. Since this confirmation testing is incomplete and detailed documentation of the remedial activities was not available for review as part of the CEQA process, the issue of VOC exposure within the building is not yet fully resolved. Therefore, mitigation measures are required to ensure that this impact would be less than significant. Implementation of the following mitigation measure, which requires that the project sponsor work with the appropriate regulatory agency to ensure that potential health risks related to contaminants in the subsurface are addressed, would reduce this potentially significant impact to a less-than- significant level. 66 The U.S. EPA’s Integrated Risk Information System (IRIS) 2011 toxicity assessment concluded that TCE exposure poses potential human health hazards for non-cancer toxicity to developing fetuses. This and other findings in the IRIS assessment of TCE indicates that women in the first trimester of pregnancy are one of the most sensitive populations to TCE inhalation exposure. Therefore, the U.S. EPA established the prompt response action level to protect against potential non-cancer outcomes, including developmental effects such as cardiac malformations. These recommendations identify women of reproductive age as the sensitive population of concern, rather than only pregnant women, because some women may not be aware of their pregnancy during the critical period of the first trimester. 67 Milano, Deno G., 2015. PG, Hazardous Materials Specialist, Groundwater Protection Program of the County of San Mateo Department of Environmental Health. Personal communication with Bruce Abelli-Amen of BASELINE, June 18. 68 Sanchez, Craig, 2016. DTSC Case Manager for 860 Charter Street (project site). Personal communication with Bruce Abelli-Amen of BASELINE, April 7. 69 Department of Toxic Substances Control, 2016, op. cit. ATTY/RESO.0032/PC RESO APPROVING CEQA - 860 CHARTER ST. EXHIBIT A REV: 06-15-17 PR Page 63 of 124