1000 Sutter Street UST Closure

Citadel EHS helped guide a complex underground storage tank environmental case at 1000 Sutter Street in San Francisco through investigation, corrective action, and ultimately regulatory closure. The case involved historical releases associated with former heating-oil USTs beneath and adjacent to a long-established urban property, requiring investigation of soil, groundwater, and soil vapor conditions within the constraints of an existing building, sidewalk, utilities, and surrounding development.

The environmental case remained open for seven years and involved two former heating-oil tanks: a 1,500-gallon UST that had been closed in place and a larger UST that was ultimately removed in 2024. Remedial activities over the course of the program also included targeted removal and off-site disposal of petroleum-impacted soil.

Citadel’s later-stage work focused on developing the technical basis for closure. The team completed supplemental site investigation, groundwater and soil vapor assessment, UST removal documentation, a second round of soil vapor sampling, and ultimately prepared the Request for Low-Threat UST Site Closure submitted in November 2025. These Citadel reports were specifically identified by the Water Board among the technical documents supporting closure.

A key challenge was demonstrating that remaining petroleum impacts could appropriately be managed under California’s risk-based closure framework despite residual contamination that could not practicably be removed. The Water Board determined that the site satisfied all eight general criteria of the State Water Board’s Low-Threat UST Case Closure Policy. It also concluded that the groundwater plume met the applicable low-threat criteria, the property satisfied residential petroleum vapor-intrusion criteria based on direct soil vapor measurements, and applicable direct-contact and outdoor-air exposure criteria were met.

In September 2026, the San Francisco Bay Regional Water Quality Control Board formally closed the case, determining that the investigation and corrective action requirements had been satisfied and that no further action related to the petroleum release was required.

The project demonstrates Citadel’s ability to take technically complex legacy environmental conditions and translate years of investigation and remediation data into a defensible regulatory closure strategy - working within real-world site constraints and providing the documentation needed to move a longstanding case to a final agency decision.

Highlights:

• No Further Action Determination
• 7-Year UST Case Closed
• Water Board Regulatory Closure
• Low-Threat UST Closure Strategy
• Soil, Groundwater & Vapor Investigation
• UST Removal & Corrective Action
• Risk-Based Closure Evaluation
• Complex Urban Site Constraints