Concerns over soil vapor contamination at 2550 Irving Street dominated the recent San Francisco government meeting, as the Department of Toxic Substances Control (DTSC) presented its findings on the presence of perchloroethylene (PCE) in the area. Despite the detection of soil vapor, DTSC concluded that there is no evidence of PCE soil vapor originating from the site itself, suggesting instead that it may be linked to unidentified off-site sources.

DTSC's investigation included six phases of site-specific analysis, which revealed concentrated soil vapor levels in the street, indicating potential off-site contamination. The agency highlighted the historical presence of over ten dry cleaners in the vicinity, which typically used PCE, as a significant factor in their assessment. DTSC emphasized the need for a conservative approach, advocating for further characterization of the neighborhood before any remediation efforts, such as soil vapor extraction (SVE), are implemented.

While SVE could reduce PCE concentrations in the short term, DTSC expressed concerns about the long-term effectiveness of such measures without fully understanding the source of the contamination. They warned that remediation efforts could inadvertently worsen conditions by drawing vapor from unidentified sources into nearby buildings.

In light of these findings, DTSC recommended deferring any immediate remediation actions until a comprehensive assessment of the area is completed. They assured the community that homes tested for vapor intrusion are currently safe for occupancy and noted that passive ventilation systems in an affordable housing project nearby would help mitigate some of the contamination.

Ultimately, DTSC found no public health or environmental reasons to deny the building permit for the project at 2550 Irving Street, urging the board to reject the appeal against it. The meeting underscored the importance of thorough environmental assessments in safeguarding public health while addressing urban development needs.