Seismic measures for Class 1 Facilities

For tanks built prior to July 2023, one or more of the following seismic protection measures must be designed, installed and maintained in order to reduce risk from seismic events:

• Flexible mechanical device(s) between storage tank and piping or sufficient piping flexibility to protect the tank and pipe connection and prevent the release of product
• Foundation driven pilings
• Anchored storage tanks
• Another seismic protection measure proposed by the facility and approved by ecology, as long as such protection measure equals or exceeds those required in this section. This may include demonstrating the storage tank meets API Standard 650 (2020) seismic design requirements, including Annex E and section E.7.3 Piping Flexibility.

Similarly, transfer pipelines must also have seismic protection measures that are designed, installed, and maintained to reduce risk from seismic events. These measures must include one or more of the following:

• Flexible mechanical device(s) between storage tank and piping or sufficient piping flexibility to protect the tank and pipe connection and prevent the release of product
• Flexible mechanical device(s) or adequate pipeline flexibility between pipes
• Pipeline supports that protect against seismic motion
• Automatic emergency isolation shutoff valves that are triggered to close during seismic events
• Another seismic protection measure proposed by the facility and approved by ecology, as long as such protection measure equals or exceeds those required in this section.

If a facility is proposing an alternative measure for either a storage tank or a transfer pipeline, the facility must submit that proposal in writing to the assigned Spills engineer for review. The Spills Program Management Team will consider proposed measures for approval. Other measures may also need to be reviewed to verify compliance such as sufficient piping flexibility.