RISE Block 5 Vapor Intrusion Mitigation
At a glance
From an automatic speech-to-text transcript; names and numbers may be misheard.
What: How PCE and TCE soil vapor contamination at the RISE Block 5 site will be mitigated before housing is occupied.
Where it stands: Informational item only. The county-approved system is to be installed before the foundation pour; the council asked for a memo on nearby plume sources and a look at standards for vent placement.
Log
2026-10-06 - City Council
The system uses a gravel layer, membrane and vents with indoor air monitoring and a contingent active venting system. Vents are designed on risers above pedestrian level, roughly 50 feet from building openings. Post-occupancy sampling is planned at 3 to 6 months, 4 to 12 months and about 24 months. City review is limited to building and fire-code plan approval, not the system's effectiveness. Mayor Moore asked for a memo on four possible plume sources; Councilmember Wang asked about screening levels and telemetry; Vice Mayor Chao asked whether any standard governs where vents may point relative to neighboring homes.